CLL-like Monoclonal B-cell Lymphocytosis Research Articles

A Snapshot of the Management of Chronic Lymphocytic Leukemia in Italy. Preliminary Analysis on over 3000 Patients Enrolled in the Gimema CLL2121 Trial

In recent years the management of patients (pts) with chronic lymphocytic leukemia (CLL) has benefited from a deeper knowledge of the mechanisms underlying the disease and from the development of novel therapeutic approaches. That notwithstanding, local and national accessibility to drugs and tests may lead to distinct “real-world” practices in terms of management of pts that are worth of being recorded and compared to understand the degree of reproducibility and applicability of international guidelines. This could also be relevant for the design of future clinical trials, more tailored to the true patient's needs. To this end, within the GIMEMA cooperative study group the observational retrospective and prospective CLL2121 study (NCT04867915) has been designed with the objective of evaluating the diagnosis and management of CLL in all hematological centers in Italy through the assessment of: 1) the methods and the actual diagnostic/prognostic work-up capacity; 2) the algorithms applied to define disease progression and treatment requirements with respect to national and international guidelines; 3) the clinical and biological variables not strictly associated with CLL, but capable of influencing the clinical course and overall survival; 4) the true incidence of some rarer complications associated with CLL. The study consists of a collection of clinico-biological data from all pts with newly diagnosed CLL, small lymphocytic lymphoma (SLL) or CLL-like monoclonal B-cell lymphocytosis (MBL), according to the iwCLL 2018 criteria in Italy. The retrospective part aims at including all cases followed at the participating centers with a diagnosis between January 2010 and September 2021, while the prospective part will include all pts with a documented diagnosis of CLL, SLL or MBL between September 2021 and September 2025. In this pilot analysis of the study, we examined pts' demographics, diagnosis, treatment line and type. Data were collected using the REDCap electronic data capture platform, analyzed using the SAS software v.9.4 and reported as numbers and frequencies. Between 2 November 2021 and 28 June 2023, 3294 eligible pts were enrolled in 75 hematology centers (out of the total of 110 centers who will be activated during the study) across the entire Italian territory. At the time of the present report, 3033 pts had clinical data available for our preliminary analysis. The vast majority of pts registered (N=2599, 85.7%) belonged to the retrospective cohort while only a minority (N=434, 14.3%) to the prospective cohort. Pts had a median age of 68 years ranging from 29 to 97; 60% of pts were males. 2630 pts (86.8%) had a diagnosis of CLL, 187 (6.2%) of SLL and 214 (7.0%) of MBL (2 missing information). Among those with available results 112 pts (12.6%) were TP53 mutated, 526 (45.6%) del(13q) positive, 174 (14.9%) del(11q) positive, 142 (11.9%) del(17p) positive and 226 (20.4%) presented a trisomy 12. The majority of pts (57.6%) were untreated, while 42.4% have been treated. Within the latter subset, 67.3% of pts have received one line of therapy, 21.4% 2 lines of therapy, 11.3% ≥3 lines of therapy. The most common therapeutic regimens were the combination of chemotherapy with an anti-CD20 antibody (39.3%), mainly rituximab, and those based on BTK inhibitors (33.3%), mainly ibrutinib. Chemotherapy alone was used in 12% of pts. Only 5% of pts was treated with the BCL2 inhibitor venetoclax. In the remaining 10% of pts, other approaches were used. This is the initial report of a nation-based real-world data collection aimed at describing the biological and clinical features of pts diagnosed with CLL in virtually all Italian hematology centers starting from 2010. The pattern of treatments highlighted in our preliminary analysis, with a wide use of the watch & wait policy and of chemoimmunotherapy, will help understand how the introduction of novel therapies impacted treatment habits also in light of the timing of the local reimbursement policy. The different time of drug access in Italy, typically delayed after the EU approval, may also have affected the limited use of venetoclax-based treatment. The continuous accrual of pts in this study will allow to obtain a close-to-registry vision of CLL management in Italy over time, in terms of coverage of the entire country but enriched with the granularity of the data and flexibility of the collection typical of a real-world study.

Other malignancies in the history of CLL: an international multicenter study conducted by ERIC, the European Research Initiative on CLL, in HARMONY

Patients with chronic lymphocytic leukemia (CLL) have a higher risk of developing other malignancies (OMs) compared to the general population. However, the impact of CLL-related risk factors and CLL-directed treatment is still unclear and represents the focus of this work. We conducted a retrospective international multicenter study to assess the incidence of OMs and detect potential risk factors in 19,705 patients with CLL, small lymphocytic lymphoma, or high-count CLL-like monoclonal B-cell lymphocytosis, diagnosed between 2000 and 2016. Data collection took place between October 2020 and March2022. In 129,254 years of follow-up after CLL diagnosis, 3513 OMs were diagnosed (27.2 OMs/1000 person-years). The most common hematological OMs were Richter transformation, myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Non-melanoma skin (NMSC) and prostate cancers were the most common solid tumors (STs).The only predictor for MDS and AML development was treatment with fludarabine and cyclophosphamide with/without rituximab (FC±R) (OR=3.7; 95% CI=2.79-4.91; p<0.001). STs were more frequent in males and patients with unmutated immunoglobulin heavy variable genes (OR=1.77; 95% CI=1.49-2.11; p<0.001/OR=1.89; 95% CI=1.6-2.24; p<0.001).CLL-directed treatment was associated with non-melanoma skin and prostate cancers (OR=1.8; 95% CI=1.36-2.41; p<0.001/OR=2.11; 95% CI=1.12-3.97; p=0.021). In contrast, breast cancers were more frequent in untreated patients (OR=0.17; 95% CI=0.08-0.33; p<0.001).Patients with CLL and an OM had inferior overall survival (OS) than those without. AML and MDS conferred the worst OS (p<0.001). OMs in CLL impact on OS. Treatment for CLL increased the risk for AML/MDS, prostate cancer, and NMSC. FCR was associated with increased risk for AML/MDS. AbbVie, and EU/EFPIAInnovative Medicines Initiative Joint Undertaking HARMONY grant n° 116026.

Risk of incident melanoma among individuals with low-count monoclonal B-cell lymphocytosis (MBL).

7577 Background: Prior research has consistently shown that patients with chronic lymphocytic leukemia (CLL) have an ~2-fold increased risk of developing melanoma compared to controls. MBL is a common condition affecting 8-10 million adults over the age of 40 years in the United States and is a precursor to CLL. Little is known about the association between MBL and melanoma. Herein, we evaluated the risk of incident melanoma in a large cohort of individuals screened for MBL. Methods: Participants from the Mayo Clinic Biobank who had no prior history of hematologic malignancy, were 40 years or older, were residents of counties surrounding Mayo Clinic, and who provided blood samples between 7/2009 and 4/2022 were included in the study. Peripheral blood mononuclear cells were screened for MBL using highly sensitive eight-color flow cytometry. Individuals with MBL were classified as CLL-like MBL (CD5+, CD20dim) or atypical MBL (CD5+, CD20+) based on immunophenotypes, and also classified as low-count MBL (LCMBL) or high-count MBL (HCMBL) based on whether the percent clonal B-cell count was &lt; 85% or ≥85%, respectively. Diagnosis of melanoma was ascertained using ICD codes and review of the electronic health records. All individuals were followed from date of sample upon which MBL screening was performed to the earliest of incident melanoma, loss to follow-up, withdrawal from the study, or September 30, 2022. We used Cox regression to estimate hazard ratios (HR) and 95% confidence intervals (CI), adjusting for age, sex, and history of melanoma in previous 5 years. Results: A total of 7,334 participants were screened for MBL, of which 1,151 (16%) individuals had MBL. Among those with MBL, 1,107 (96.2%) had CLL-like MBL and 1098 (95.4%) had LC MBL. The median age at entry into the MBL screening cohort was 67 years (range 40-101) and 37% were male; individuals with MBL were older (median age 72 vs 65 years) and male (49% vs 35%). After a median follow-up of 2.9 years (range 0-13.2), 121 of the 7,334 (1.6%) participants developed incident melanoma after the date of MBL screening. The 10-year cumulative incidence of melanoma among individuals with MBL was 7.8% (95% CI 4.5-13.5%) compared to 3.4% (2.7-4.4%) in those who screened negative for MBL. After adjusting for age, sex, and history of prior melanoma, we found a 1.81-fold increased risk of incident melanoma (95% CI 1.19-2.76) among individuals with MBL. The increased risk of melanoma persisted when the analysis was restricted to individuals with LCMBL (HR = 1.84; 95% CI 1.21-2.82). Conclusions: In the largest MBL screening cohort to date, we found that LCMBL, a common condition, was associated with an 84% elevated risk of melanoma, similar to the ~2-fold increased risk observed in patients with CLL. These data, together with our prior findings of a heightened risk of serious infections and lymphoid malignancies, suggest that individuals with LCMBL are at increased risk for adverse health outcomes.

Identification of Three Unique Clusters of Serum Proteins with Distinctive Functionalities in IGHV-Mutated MBL

Background. CLL-like monoclonal B-cell lymphocytosis (MBL) is considered a requisite precursor of CLL. Since MBL is also associated with inflammatory disorders, other cancers, and increased incidence of infections (Landgren et al, 2007; Moreira et al, 2013; Solomon et al, 2016), an underlying immune alteration might be at the root of the condition's onset and progression to CLL. Patients with CLL whose clone expresses mutated (M-CLL) and unmutated (U-CLL) IGHV genes differ in inflammatory profiles, with the latter exhibiting a more activated immune system, in line with the distinct capabilities of the two CLL subtypes to interact with the microenvironment with M-CLL being more anergic. Here, we studied the serum protein profiles in MBL, CLL patients, and age-matched healthy donors (HD). Since a sufficient number of MBL subjects with unmutated IGHV was not available, only MBL with mutated IGHV (M-MBL) and M-CLL patients were analyzed. Objectives. 1. Compare serum proteomic profiles of the three subsets of individuals. 2. Identify protein clusters more restricted to M-MBL. Methods. In all, 34 subjects were studied: 10 M-MBL, 12 M-CLL, and 12 HD. All individuals were treatment naive at sample collection, and all MBL subjects remained stable over a median follow-up of 53 months. Serum protein levels were quantified using a library of modified single-stranded DNA aptamers (SOMAmers) that measure 1,310 protein targets (SomaLogic). P-values <0.05 were required to consider protein levels as differentially expressed (DE) between groups. The protein-specific STRING database v11.5 was used for analyses. Functional enrichments were selected according to i) confidence > 0.4; ii) lowest significant (< 0.05) FDR P-values; iii) network description, focusing only on informative disease-related pathways. The Markov Cluster (MCL) algorithm was used to identify clusters of non-redundant, upregulated proteins related to functionally-associated networks. Serum levels of selected molecules were validated using the U-PLEX Platform (MSD) in 24 HD, 29 M-MBL and 25 M-CLL. Results: Levels of 34 proteins were DE in MBL vs. HD [19 upregulated (u), 56%; and 15 downregulated (d)]; 288 in CLL vs. HD [16u, 6%; and 272d]; and 419 in MBL vs. CLL [411u, 98%; and 8d]. U-PLEX assays validated the significantly increased levels of IL8 (P = 0.020) and CXCL11 (P = 0.038) in MBL vs. HD and IL4 (P = 0.029) in MBL vs. CLL. STRING analysis of the DE proteins between groups is shown in Table 1. Pathways related to viral infections were only highlighted in MBL vs. HD. Cytokine activity, receptor signaling, and the PI3K-Akt pathway that promotes proliferation, were detected in both MBL vs. HD (mainly upregulated) and CLL vs. HD (mostly downregulated). The last three pathways were also observed for MBL vs. CLL (upregulated in MBL). To unravel the previous comparison, the MCL algorithm was used, and this disclosed 3 main clusters of non-redundant, upregulated proteins in MBL (Table 2). Cluster #1 involved pathways related to receptor binding (including growth factor receptors such as the ErbB family) and signal transduction, with an emphasis on the PI3K-Akt pathway. The activation of these pathways promotes cell survival and migration. Cluster #2 included cell division pathways and upregulated HMGB1 and MYC, both allowing gene transcription and proliferation. Cluster #3 concerned immune system activation, in particular inflammatory responses involving innate immune cells, viral interactions, IL17, and the JAK-STAT pathway, the latter playing a major role in cytokine receptor signaling. Conclusions: The serum proteins in M-MBL suggest immune stimulation, which underwent considerable change after transition to M-CLL. This highlights an evolving serum proteome functionality with a slight activation of the immune system in MBL that declines upon transition to CLL. Clustering analysis identified 3 non-redundant, upregulated protein clusters in M-MBL compared to M-CLL. These findings suggest immune stimulation as a characteristic feature in MBL that is not operative in CLL and point out 3 groups of distinct pathological networks that may have a role in disease onset and tumor control. Future studies, focusing on specific cell subsets, will be performed to disclose the main cell orchestrators and their exact role within each cluster, to ultimately develop preemptive strategies. Acknowledgments. GB was supported by Fundación Alfonso Martín Escudero. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Abstract 5256: Incidence of squamous cell carcinoma (SCC) in a large screening cohort of monoclonal B-cell lymphocytosis (MBL)

Abstract MBL is a common pre-malignant condition characterized by circulating clonal B-cells with an absolute B-cell count &amp;lt;5x109/L and no lymphadenopathy, organomegaly, or cytopenias. MBL is the precursor to CLL. The incidence of cutaneous SCC in CLL is significantly higher compared to controls. The incidence of SCC in MBLs has not yet been determined. Study participants from the Mayo Clinic Biobank who had no prior history of hematologic malignancy, were 40 years or older, and were Olmsted County residents completed a health questionnaire and provided blood samples between 7/2009 and 12/2020. Stored peripheral blood mononuclear cells were screened for MBL using flow cytometry. We defined three MBL immunophenotypes: CLL-like MBL (CD5+, CD20dim), atypical MBL (CD5+, CD20+), and non-CLL-like MBL (CD5-, CD20+). MBL individuals were also classified by cell count into low-count MBL (LC-MBL) and high-count MBL (HC-MBL), with HC-MBL having a percent clonal B-cell count ≥85%. Data on newly diagnosed SCC was abstracted from the medical records, and prior history of skin cancer before sample collection was ascertained from patient questionnaires. Individuals were followed from sample date to the earliest of SCC, death, loss to follow-up, progression, or 12/31/2020. Cumulative SCC incidence was adjusted for competing risk of death. Cox regression was used to calculate hazard ratios (HR) and 95% confidence intervals (CIs) adjusted for age and sex. A total of 5,470 participants were screened for MBL and included 949 (17%) with LC-MBL, 63 (1%) with HC-MBL, and 4,458 (81%) controls (negative for MBL). Individuals with HC-MBL (median age 75 years) or LC-MBL (median age 73 years) were significantly older (P&amp;lt;0.001) than controls (median age 66 years). There were 41 (65%) males among HC-MBL, 447 (47%) among LC-MBL, and 1,551 (35%) among controls. Prior skin cancer history was highest among HC-MBLs (N=17, 27%) or LC-MBLs (N=236, 25%) compared to controls (N=767, 17%). After a median follow-up of 18 months (range 0-138), 154 of the 5,470 individuals were identified to have incident SCC following MBL screening. At least one SCC was observed in 3 individuals with HC-MBL, 33 individuals with LC-MBL, and 118 controls. The 5- and 10-year cumulative incidence of SCC in individuals with MBLs was 7% and 16%, respectively; control estimates were 4% and 8%, respectively. However, after adjusting for age and sex, we observed no evidence of an association between MBL and risk of incident SCC (HR=0.95, CI=0.65-1.40, P=0.80), nor when we stratified individuals by age or by sex (all P&amp;gt;0.05). In the largest MBL screening cohort to date, individuals with MBL do not have an increased risk of incident SCC compared to controls. In contrast to individuals with CLL, these individuals with screening MBL do not need increased dermatologic examination for skin cancer, which is important given the high prevalence of MBL (18% of the population above age 40). Citation Format: Ahmed Nadeem Ansari, Sara J. Achenbach, Sameer A. Parikh, Geffen Kleinstern, Aaron D. Norman, Kari G. Rabe, Connie E. Lesnick, Timothy G. Call, Janet E. Olson, James R. Cerhan, Neil E. Kay, Celine M. Vachon, Esteban Braggio, Curtis A. Hanson, Tait D. Shanafelt, Christian L. Baum, Susan L. Slager. Incidence of squamous cell carcinoma (SCC) in a large screening cohort of monoclonal B-cell lymphocytosis (MBL) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5256.

Prevalence and Overall Survival of Low Count Monoclonal B-Cell Lymphocytosis (LC-MBL): A Screening Study of 8,297 Individuals from the Mayo Clinic Biobank

Prevalence and Overall Survival of Low Count Monoclonal B-Cell Lymphocytosis (LC-MBL): A Screening Study of 8,297 Individuals from the Mayo Clinic Biobank

Early Immune Profile Assessment By Flow Cytometry Predicts Severe COVID-19 Pneumonia

▪Background and ObjectiveThe rapid spread of the COVID -19 pandemic and the high variability of the course of the disease make it essential to search for early predictors of outcome. The objective of our study is to predict severe SARS COV2 pneumonia using early cytometric profilesMaterial and MethodsProspective and observational study of adults with confirmed COVID-19 infection admitted on Emergency Department (ED). We collected epidemiological, clinical and laboratory data of every patient until they were discharged or died. Multiparametric flow cytometry (FC) analysis of T-lymphocytes (CD4, CD8, CD4 activated, CD8 activated, naïve (Tn), central-memory (Tcm), effector-memory (Tem), effector (Te) and Th17 subsets), B-lymphocytes (naïve, memory, transitional subsets, and assessment of clonality), NK cells, plasmablasts, p-DCs (plasmacytoid dendritic cells), m-DCs (myeloid dendritic cells), basophils, and monocytes (MO1, MO2, MO3, slan+ MO3) was performed on whole peripheral blood collected on EDTA, before immunosuppressive therapy was started. We designed a 7-tube 8-color experimental panel. Cell surface staining of 2 × 106 cells was performed and at least 500 000 total events were acquired for the assessment of plasmablasts, p-DCs, m-DCs, basophils, and the monocyte subsets; for the study of B, T and NK-lymphocyte populations we acquired at least 100 000 total events (FACS Canto II; BD Biosciences). Severity was assessed on the basis of World Health Organization´s (WHO) international 10 level ordinal scale (WHOs) and also according to 4 respiratory status, based on SpO2(peripheral blood oxygen saturation)/FIO2 (fraction of inspired oxygen) ratio (SpFi). SpFi group 1 >452, SpFi2 2: 315-452; SpFi 3 236-315, SpFi 4: <236 (respiratory distress)Results53 patients were included: epidemiological and clinical data available on table 1. 23 patients (43.39%) arrived to SpFi4 status. WHOs >6 (WHO 6:oxygen by non invasive ventilation or high flow) was achieved by 20 patients (37.7%)Good prognosis (meaning SpFi1 as the worse respiratory status in the follow -up) was associated to cytometric profiles: there was a significant increase in CD3, p-DCs, m-DCs, basophils, monocytes, Tcm, % of lymphocytes and CD3/CD19 ratio whereas there was a significant reduction in CD19, % of neutrophils and % Neutrophils/% lymphocyte ratio. In the SpFi4 group, there was a significant reduction of CD3, p-DCs, m-DCs, plasmablasts and CD3/NK ratio. In patients starting in SpFi group 1-2 in the ED but progressing to SpFi 3-4 during the follow up (27 patients), there was a statistically significant relation with Tn, Te and Tn/Te ratio (Tn/Te ratio <0.717: OR 13.5 (p 0.002, [95% CI 2.552-71.403). Initial SpFi1 patients that evolved to SpFi 3-4 during follow up (10 patients), presented a Tn/Te ratio < 0.717 with an OR 11.556 (p =0.005, [95% CI 2.059-64.853]).Plasmablasts < 0.075 and CD3/NK <5.71, were identified as independent risk factors for SpFI4 during follow up. After multivariable analysis, both variables kept their significance: CD3/NK (OR 11,247, p=0.005) and plasmablasts (OR 12,524 , p=0.004). About prediction of WHOs >6, multivariable analysis showed CD3/NK <5.71 (OR 22,240 [95%CI 2,340-211,342] p= 0.007) and plasmablasts<0.075 (OR 28.635 [95% CI 3,187-257,301] p=0.003).A score (0,1,2) comprising both risk factors, was significantly predictive of SpFI4, regardless of the initial respiratory status, age or days from symptoms onset. In our cohort, only 1/15 (6.7%) patients with 0 points (neither plasmablasts nor CD3/NK score), arrived to SpFi4. However, 10/11 (90.9%) patients with 2 points, reached to SpFi4 respiratory status (C-index = 0.837) Same score was applied to predict WHOs > 6: 90.9% with 2 points progressed to WHO>6 and 0/15 patients with 0 points reached the same goal (C-index = 0.872)An incidental finding of 4 indolent B-lymphoproliferative disorders (2CLL-like MBLs and 2non -CLL-like MBL), was found, and they were associated with older age and progression to death.ConclusionsFlow cytometry on whole peripheral blood samples of SARS-COV2 pneumonia patients, collected before corticosteroid or immunosuppressive therapy, could identify cytometric patterns associated to prognosis. Plasmablasts, mDCs and pDCs levels as well as CD3/NK ratio, are associated to a worse respiratory status, while Tn/Te ratio could detect non-severe patients who will require high-flow oxygen devices during follow up. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

High Throughput Immunoprofiling of Low Count B Lymphocytosis Reveals a Distinct T Cell Receptor Repertoire from Chronic Lymphocytic Leukemia

Mounting evidence supports the notion that T cells are crucial for the survival and expansion of the malignant clone in chronic lymphocytic leukemia (CLL). Recently, NGS immunoprofiling of the T cell receptor (TR) gene repertoire in CLL revealed “disease-specific” TR clonotypes shared by different patients that persisted and further expanded over time, suggesting that antigen drive likely underlies T-cell expansions in CLL. CLL-like Monoclonal B-cell Lymphocytosis (MBL) is characterized by the presence of CLL-like clonal B cells in lower numbers compared to CLL with no other evidence of disease. MBL is distinguished into high and low count (HC-MBL and LC-MBL, respectively). HC-MBL may evolve to CLL requiring treatment and is considered a pre-leukemic condition, while LC-MBL has an unclear, if any, link to CLL, posing a particular conundrum, especially considering that despite sharing CLL-associated genomic aberrations it displays a distinct immunoglobulin gene repertoire. The precise mechanisms underlying MBL onset and/or progression into overt CLL remain unknown. Arguably, these could entail the acquisition of particular genetic lesions and/or extrinsic signals delivered to the clonal B cells, including those emanating from T cells. Considering the above, here we aimed at characterizing T cells in the early steps of CLL ontogeny by detailed immunoprofiling of the TR gene repertoire in LC-MBL, a thus far unexplored area.The study group comprised 43 individuals with CLL-like (CD5+) LC-MBL and 7 individuals with non CLL-like LC-MBL (atypical CLL-like and CD5- LC-MBL). The presence of a LC-MBL population was confirmed by a standardized flow cytometry protocol. TR beta chain (TRB) gene rearrangements were RT-PCR amplified with the use of the BIOMED 2 protocol. Sequencing libraries were prepared with the TruSeq DNA LT Kit and run on the MiSeq Sequencer using the MiSeq Reagent Kit v3 (500 cycles). Raw NGS reads were subjected to data filtering based on read length and quality. Filtered-in sequences were submitted to IMGT/HighV-QUEST and an in-house bioinformatics pipeline for clonotype computation and repertoire characterization.Overall, 9,385,319 productive filtered-in TRBV-TRBD-TRBJ rearrangement sequences were evaluated corresponding to an average of 32,205 different (unique) clonotypes/sample (clonotype: same TRBV gene and CDR3 amino acid sequence). Skewing of the TRBV repertoire was identified in both LC-MBL categories. In specific, the 4/5 most frequently utilized TRBV genes were identical between the 2 categories (TRBV29-1, TRBV12-3, TRBV19, TRBV6-5) and cumulatively accounted for a virtually identical part of the respective repertoire (28.7% versus 28.6%). Comparison to our published data from CLL revealed similarities regarding TRBV gene usage, particularly for CLL-like LC-MBL. Oligoclonality was evident in both MBL categories with the 10 most frequent clonotypes accounting for 21.3% of the total repertoire in CLL-like LC-MBL and 20.3% in non CLL-like LC-MBL, again not differing significantly from CLL (26.3%). All the above 3 entities were clearly more oligoclonal in comparison to 2 healthy control samples from aged-matched used as a reference. Cluster analysis among the 10 most frequent clonotypes of all LC-MBL and CLL samples revealed infrequent matches between: (i) different CLL-like LC-MBL samples (24/430, 0.055%); (ii) CLL-like and non CLL-like LC-MBL (8/500, 0.016%); and, (iii) CLL-like LC-MBL and CLL (2/680, 0.002%).Altogether, these findings indicate that, similar to CLL, antigen drive likely underlies T-cell expansions also in LC-MBL. However, despite similar TRBV gene usage and degree of oligoclonality, scant shared clonotypes were identified, thus indicating that the antigenic stimuli and/or immune processes shaping the TR profiles in LC-MBL and CLL are distinct. DisclosuresAgathangelidis:Gilead Sciences: Research Funding. Stamatopoulos:Gilead: Consultancy, Honoraria, Research Funding; Novartis SA: Research Funding; Abbvie: Honoraria, Research Funding; Janssen Pharmaceuticals: Honoraria, Research Funding. Ghia:Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen Pharmaceuticals: Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Honoraria.

Reduced expansion of CD94/NKG2C+ NK cells in chronic lymphocytic leukemia and CLL-like monoclonal B-cell lymphocytosis is not related to increased human cytomegalovirus seronegativity or NKG2C deletions.

Dysregulated NK cell-mediated immune responses contribute to tumor evasion in chronic lymphocytic leukemia (CLL), although the NK cell compartment in CLL-like monoclonal B-cell lymphocytosis (MBL) is poorly understood. In healthy individuals, human cytomegalovirus (HCMV) induces the expansion of NK cells expressing high levels of CD94/NKG2C NK cell receptor (NKR) specific for HLA-E. We analyzed the expression of NKG2A, NKG2C, ILT2, KIR, CD161, and CD57 in 24 MBL and 37 CLL. NKG2C was genotyped in these patients and in 81 additional MBL/CLL, while NKG2C gene expression was assessed in 26 cases. In 8 CLL patients with increased lymphocytosis (≥20×109 /L), tumor HLA-E and HLA-G expression was evaluated. NKR distribution did not significantly differ between MBL and CLL patients, although they exhibited reduced NKG2C+ NK cells compared with a non-CLL group (4.6% vs 12.2%, P=.012). HCMV+ patients showed increased percentages of NKG2C+ NK cells compared with HCMV- (7.3% vs 2.9%, P=.176). Frequencies of NKG2C deletions in MBL/CLL were similar to those of the general population. Low/undetectable NKG2C expression was found among NKG2C+/- (45%) and NKG2C+/+ (12%) patients. CLL cases with increased lymphocytosis displayed especially reduced NKG2C expression (1.8% vs 8.1%, P=.029) and tumor cells with high HLA-E (>98%) and variable HLA-G expression (12.4%, range: 0.5-56.4). CLL patients with low NKG2C expression (<7%) showed shorter time to first treatment (P=.037). Reduced percentages of CD94/NKG2C+ NK cells were observed in CLL and MBL patients independently of HCMV serostatus and NKG2C zygosity, particularly in CLL patients with increased lymphocytosis, which could potentially be related to the exposure to tumor cells.

Chronic lymphocytic leukemia–like monoclonal B-cell lymphocytosis exhibits an increased inflammatory signature that is reduced in early-stage chronic lymphocytic leukemia

Several studies in chronic lymphocytic leukemia (CLL) patients have reported impaired immune cell functions, which contribute to tumor evasion and disease progression. However, studies on CLL-like monoclonal B-cell lymphocytosis (MBL) are scarce. In the study described here, we characterized the immune environment in 62 individuals with clinical MBL, 56 patients with early-stage CLL, and 31 healthy controls. Gene expression arrays and quantitative reverse transcription polymerase chain reaction were performed on RNA from CD4+ peripheral blood cells; serum cytokines were measured with immunoassays; and HLA-DR expression on circulating monocytes, as well as the percentages of Th1, cytotoxic, exhausted, and effector CD4+ T cells, were evaluated by flow cytometry. In addition, cell cultures of clonal B cells and CD14-enriched or -depleted cell fractions were performed. Strikingly, MBL and early-stage CLL differed in pro-inflammatory signatures. An increased inflammatory drive orchestrated mainly by monocytes was identified in MBL, which exhibited enhanced phagocytosis, pattern recognition receptors, interleukin-8 (IL8), HMGB1, and acute response signaling pathways and increased pro-inflammatory cytokines (in particular IL8, interferon γ [IFNγ], and tumor necrosis factor α). This inflammatory signature was diminished in early-stage CLL (reduced IL8 and IFNγ levels, IL8 signaling pathway, and monocytic HLA-DR expression compared with MBL), especially in those patients with mutations in IGHV genes. Additionally, CD4+ T cells of MBL and early-stage CLL exhibited a similar upregulation of Th1 and cytotoxic genes and expanded CXCR3+ and perforin+ CD4+ T cells, as well as PD1+ CD4+ T cells, compared with controls. Cell culture assays disclosed tumor-supporting effects of monocytes similarly observed in MBL and early-stage CLL. These novel findings reveal differences in the inflammatory environment between MBL and CLL, highlighting an active role for antigen stimulation in the very early stages of the disease, potentially related to malignant B-cell transformation.

Prevalence and Immunophenotypic Characteristics of Monoclonal B-Cell Lymphocytosis in Healthy Korean Individuals With Lymphocytosis.

Epidemiological studies of monoclonal B-cell lymphocytosis (MBL) have been conducted in limited geographical regions. Little is known about the prevalence of MBL in Asia. We investigated the prevalence and immunophenotypic characteristics of MBL in Koreans who had idiopathic lymphocytosis (lymphocyte count >4.0×109/L) and were ≥40 years of age. A total of 105 leftover peripheral blood samples met these criteria among those from 73,727 healthy individuals who visited the Health Promotion Center, Samsung Medical Center, Korea, from June 2018 to August 2019. The samples were analyzed using eight-color flow cytometry with the following monoclonal antibodies: CD45, CD5, CD10, CD19, CD20, CD23, and kappa and lambda light chains. The overall prevalence of MBL in the study population was 2.9% (3/105); there was one case of chronic lymphocytic leukemia (CLL)-like MBL (CD5+CD23+), one case of atypical CLL-like MBL (CD5+CD23−), and one case of CD5−MBL with a lambda restriction pattern. This is the first study on the MBL prevalence in an East Asian population, and it reveals a relatively low prevalence of MBL in healthy Korean individuals with lymphocytosis.

Deciphering the CXCL9-CXCL10-CXCL11/CXCR3 Axis in CLL-like Monoclonal B-Cell Lymphocytosis and Chronic Lymphocytic Leukemia: A New Target for Immune Activation?

Deciphering the CXCL9-CXCL10-CXCL11/CXCR3 Axis in CLL-like Monoclonal B-Cell Lymphocytosis and Chronic Lymphocytic Leukemia: A New Target for Immune Activation?

Reduced Expression of the CD94/NKG2C NK Cell Receptor in Chronic Lymphocytic Leukemia (CLL) and CLL-like Monoclonal B-Cell Lymphocytosis (MBL)

Background. Dysregulated NK-cell responses have been reported in chronic lymphocytic leukemia (CLL) patients, but little is known about the NK cell compartment in CLL-like monoclonal B cell lymphocytosis (MBL). Human cytomegalovirus (HCMV) infection induces an adaptive reconfiguration of the NK cell compartment characterized by the differentiation and persistent expansion of a subset displaying the CD94/NKG2C NK receptor (NKR). Moreover, a deletion of the NKG2C (KLRC2) gene has been reported to modulate the magnitude of the NK cell repertoire redistribution. Little is known about the expression of NKG2C in CLL and MBL patients. Aims. To analyse the distribution of NKR, with special attention to NKG2C, in MBL and CLL patients, assessing the relation of the NK cell immunophenotype with clinical features. Methods. The study cohort included 61 patients, 24 were diagnosed with clinical MBL and 37 were treatment-naïve CLL (32/37 Binet A). The expression of NKG2C, NKG2A, ILT2 (LIR1, LILRB1), CD161, CD57 and KIRs (identified with a cocktail of monoclonal antibodies) was assessed by flow cytometry in peripheral blood NK cells. The NKG2C (KLRC2) genotype was analysed in a larger representative MBL/CLL cohort (n=135). Results. The proportions of NK cells were reduced in CLL patients compared to MBL (median 5.5% vs. 10%; P=0.003), whereas their absolute numbers were increased (median 0.85x109/L vs. 0.57x109/L; P=0.002). No significant differences between MBL and CLL were detected regarding the distribution of the different NKR: NKG2C (median: 2.7 vs. 5.9%, respectively), NKG2A (31.4 vs. 30.8%), ILT2 (18.0 vs.15.8%), KIRs (54.4 vs. 52.7%), CD161 (16.1 vs. 16.4%) and CD57 (40.4 vs. 38.9%). Though a reduced NKG2C expression was noticed in both entities, it was specially marked in patients with a greater (&gt;30x109 cells/L) lymphocytosis (1.4 vs. 7.7%, P=0.016). The proportions of NKG2C+ NK cells in HCMV+ patients (85%, 47/55) as compared to HCMV- individuals were not significantly different (6.3% vs. 2.9%, respectively). HCMV+ patients showed a significantly lower NKG2C expression when compared with two independent age-matched cohorts of HCMV+ non-CLL/-MBL individuals, including 43 non-metastatic breast cancer patients (4.2% vs. 15.3% , P&lt;0.001); and 30 renal transplantation donors (4.2% vs.12.4% in P=0.028). The frequencies of NKG2C+/+ (56%), NKG2C+/del (37%) and NKG2Cdel/del (7%) genotypes were comparable to those previously defined in healthy blood donors. Moreover, cases with very low (&lt;2%) or undetectable NKG2C expression were found in NKG2Cdel/del patients (100%, 6/6), but also among NKG2C+/- (45%, 10/22) and NKG2C+/+ (12%, 3/26) genotypes. Conclusions. 1. MBL and CLL exhibited low proportions of NKG2C+ NK cells. This immunophenotype was particularly evident in CLL patients with increased lymphocytosis and could not be explained by differences in HCMV seropositivity, NKG2C zygosity nor age. 2. Additional studies are required to define the mechanism(s) and putative implications of the reduced NKG2C expression in these lymphoproliferative disorders. Acknowledgements. PI11/1621; PI15/437; 2017/SGR437; Fundació La Caixa; Fundación Española de Hematología y Hemoterapia (FEHH). Disclosures Gimeno: JANSSEN: Consultancy, Speakers Bureau; Abbvie: Speakers Bureau. Abrisqueta:Celgene: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria, Other: Travel, Accommodations, expenses, Speakers Bureau; Janssen: Consultancy, Honoraria, Other: Travel, Accommodations, expenses, Speakers Bureau; Roche: Consultancy, Honoraria, Other: Travel, Accommodations, expenses, Speakers Bureau. Bosch:Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Kyte: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Acerta: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; F. Hoffmann-La Roche Ltd/Genentech, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Takeda: Honoraria, Research Funding; AstraZeneca: Honoraria, Research Funding.

Gene Expression and Cytokine Analyses Identify Markers of Progression from CLL-like Monoclonal B-Cell Lymphocytosis to Chronic Lymphocytic Leukemia

Gene Expression and Cytokine Analyses Identify Markers of Progression from CLL-like Monoclonal B-Cell Lymphocytosis to Chronic Lymphocytic Leukemia

Immunophenotypic profile and clinical outcome of monoclonal B-cell lymphocytosis in kidney transplantation.

Monoclonal B-cell lymphocytosis (MBL) is a lymphoproliferative disorder characterized by clonal expansion of a B-cell population in peripheral blood of otherwise healthy subjects. MBL is divided into CLL (chronic lymphocytic leukemia)-like, atypical CLL-like and non-CLL MBL. The aim of this study was to evaluate immunophenotypic characteristics and clinical outcomes of MBL in kidney transplant (KT) recipients. We retrospectively evaluated 593 kidney transplant (KT) recipients in follow-up at our center. Among them, 157 patients underwent peripheral blood flow cytometry for different clinical indications. A 6-color panel flow cytometry was used to diagnose MBL. This condition was detected in 5 of 157 KT recipients. Immunophenotypic characterization of MBL showed four cases of non-CLL MBL and one case of CLL-like MBL. At presentation, median age was 65years (range 61-73). After a median follow-up of 3.1years (95%CI; 1.1-5) from diagnosis, patients did not progress either to CLL or to lymphoma. The disorder did not increase the risk of malignancy, severe infections, graft loss and mortality among our KT recipients. Surprisingly, all cases were also affected by concomitant monoclonal gammopathy of undetermined significance, which did not progress to multiple myeloma during follow-up. In conclusion, our data suggest that MBL is an age-related disorder, with non-CLL MBL being the most common subtype among KT recipients.

Abstract 3256: The prevalence of non-chronic lymphocytic leukemia (CLL) phenotype monoclonal B-cell lymphocytosis (MBL) in a population-based cohort of U.S. adults

Abstract Introduction: CLL phenotype (CD5+CD23+CD20dim) MBL is present in 5-10% of the general population. The prevalence and outcomes of adults with non-CLL like MBL (including CD5+CD23-, CD5+CD20bright, and CD5-) are not known. We screened for MBL using highly sensitive flow-cytometry in a clinic-based cohort of adults from the Mayo Clinic Biobank. Methods: The Mayo Clinic Biobank is a large scale bio-repository of 50,000 adults seen in primary care-based clinics. Herein, we focused on those adults ≥40 years who had stored peripheral blood mononuclear cells available (10% of the overall cohort). We screened for MBL using an 8 color (CD38, CD45, Kappa, Lambda, CD19, CD23, CD5 and CD20) flow cytometry assay validated to detect clonal B-cell events to the 0.005% level (1/20,000 events). Chi-square tests were used to assess associations with demographic characteristics. Cox regression models were used to estimate hazard ratios (HR) and 95% confidence intervals (95% CI) for death. Results: A total of 2594 adults were screened; their median age was 63 years (range, 40-96) and 1111 (43%) were male. 2445/2594 (94%) individuals had interpretable flow cytometry results. A total of 336 (14%) individuals had MBL identified, of whom 276 (82%) had CLL-like MBL and 60 (18%) had non-CLL like MBL (including 39 adults with CD5- and 21 with CD5+CD23- or CD5+CD20 bright phenotype). A strong association between age and the prevalence of non-CLL like MBL was observed, with 0/278 (0%) in 40-49 years, 6/613 (1%) in 50-59 years, 20/674 (3%) in 60-69 years, 21/490 (4%) in 70-79 years, and 13/114 (11%) ≥80 years demonstrating non-CLL like MBL (p&amp;lt;0.001). Non-CLL like MBL was more common in men compared to women (5% vs. 1%; p&amp;lt;0.001). Compared to adults with no MBL, a higher proportion of non-CLL like MBL had a first-degree relative with a lymphoproliferative disorder (8% vs. 17%; p=0.03), and prior non-hematologic cancer (22% vs. 38%, p=0.006). The remainder of the present analysis is focused on adults with non-CLL like MBL (n=60). After a median follow-up of 5 years (range 0-8 years), 3/60 (5%) adults with non-CLL like MBL developed a hematologic malignancy (one myelodysplastic syndrome, two mantle cell lymphoma) compared to 5/2109 (0.2%) adults with no MBL (two large cell lymphoma, one multiple myeloma, one acute myeloid leukemia, one myelofibrosis). Among adults with non-CLL like MBL, the estimated 7-year overall survival (OS) was 79% compared to 94% in those with no MBL (p&amp;lt;0.001, HR for death 3.8, 95% CI 1.98-7.3). After adjusting for age, sex, and self-reported prior non-hematologic cancer, the HR for death was 1.50 (95% CI 0.74-3.05, p=0.26). Conclusion: In this large study, ~1 of 40 adults seen in a primary care setting had non-CLL like MBL. The prevalence of the non-CLL phenotype MBL increased with age. With current follow-up, the risk of progression to an overt lymphoproliferative neoplasm appears to be low. Citation Format: Sameer A. Parikh, Sara J. Achenbach, Kari G. Chaffee, Neil E. Kay, Connie E. Lesnick, James R. Cerhan, Curtis A. Hanson, Tait D. Shanafelt, Susan L. Slager. The prevalence of non-chronic lymphocytic leukemia (CLL) phenotype monoclonal B-cell lymphocytosis (MBL) in a population-based cohort of U.S. adults [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3256.

Lymphoma-like monoclonal B cell lymphocytosis in a patient population: biology, natural evolution, and differences from CLL-like clones.

High-count monoclonal B cell lymphocytosis (MBL) with a chronic lymphocytic leukemia (CLL) phenotype is a well-known entity, featuring 1-4% annual risk of progression towards CLL requiring treatment. Lymphoma-like MBL (L-MBL), on the other hand, remains poorly defined and data regarding outcome are lacking. We retrospectively evaluated 33 L-MBL cases within our hospital population and compared them to 95 subjects with CLL-like MBL (C-MBL). Diagnoses of L-MBL were based on asymptomatic B cell clones with Matutes score < 3, B cells < 5.0 × 103/μl, and negative computerized tomography scans. We found that median B cell counts were considerably lower compared to C-MBL (0.6 vs 2.3 × 103/μl) and remained stable over time. Based on immunophenotyping and immunogenetic profiling, most L-MBL clones did not correspond to known lymphoma entities. A strikingly high occurrence of paraproteinemia (48%), hypogammaglobulinemia (45%), and biclonality (21%) was seen; these incidences being significantly higher than in C-MBL (17, 21, and 5%, respectively). Unrelated monoclonal gammopathy of undetermined significance was a frequent feature, as the light chain type of 5/12 paraproteins detected was different from the clonal surface immunoglobulin. After 46-month median follow-up, 2/24 patients (8%) had progressed towards indolent lymphoma requiring no treatment. In contrast, 41% of C-MBL cases evolved to CLL and 17% required treatment. We conclude that clinical L-MBL is characterized by pronounced immune dysregulation and very slow or absent progression, clearly separating it from its CLL-like counterpart.

Restricted T cell receptor repertoire in CLL-like monoclonal B cell lymphocytosis and early stage CLL

ABSTRACT Analysis of the T cell receptor (TR) repertoire of chronic lymphocytic leukemia-like monoclonal B cell lymphocytosis (CLL-like MBL) and early stage CLL is relevant for understanding the dynamic interaction of expanded B cell clones with bystander T cells. Here we profiled the T cell receptor β chain (TRB) repertoire of the CD4+ and CD8+ T cell fractions from 16 CLL-like MBL and 13 untreated, Binet stage A/Rai stage 0 CLL patients using subcloning analysis followed by Sanger sequencing. The T cell subpopulations of both MBL and early stage CLL harbored restricted TRB gene repertoire, with CD4+ T cell clonal expansions whose frequency followed the numerical increase of clonal B cells. Longitudinal analysis in MBL cases revealed clonal persistence, alluding to persistent antigen stimulation. In addition, the identification of shared clonotypes among different MBL/early stage CLL cases pointed towards selection of the T cell clones by common antigenic elements. T cell clonotypes previously described in viral infections and immune disorders were also detected. Altogether, our findings evidence that antigen-mediated TR restriction occurs early in clonal evolution leading to CLL and may further increase together with B cell clonal expansion, possibly suggesting that the T cell selecting antigens are tumor-related.

Prevalence of Low Count (LC) Monoclonal B Cell Lymphocytosis (MBL) and Serious Infections in a Population-Based Cohort of U.S. Adults Participating in a Large Bio-Repository

Background: There is little prospective, longitudinal data on the health outcomes of low count MBL in the U.S. adult population. We screened for MBL in asymptomatic adults with normal blood counts using highly sensitive flow-cytometry in a clinic-based cohort of participants from the Mayo Clinic Biobank and explored the relationship between MBL and risk of hospitalization with infection.Methods: The Mayo Clinic Biobank is a large scale biorepository of 50,000 adults (age>18) seen in primary care-based clinics. All consented participants completed a health history questionnaire and provided blood samples. For the present study, we focused on the study participants from Olmsted County, Minnesota, 40 years of age or older who had stored PBMC. We used these PBMC to screen for MBL using an 8 color (CD38, CD45, Kappa, Lambda, CD19, CD23, CD5 and CD20) flow cytometry assay validated to consistently detect clonal B-cell events to the 0.005% level (1/20,000 events). The sensitivity of this approach of collecting 500,000 events from isolated PBMC is 2-3-fold higher than collecting 500,000 events from whole blood due to the increased concentration of lymphocytes in these samples.Infections associated with hospitalization were considered serious or life-threatening infections. Every hospitalization at both Mayo Clinic and Olmsted Medical Center hospitals in Olmsted County, MN following the sample collection was reviewed to document hospitalization with infection. Data on hospitalization with infection was abstracted from clinical records using our previously published approach (Moriera, Leukemia 27:136). This approach allows medical record validation and review of detailed clinical and treatment information related to infection. For this analysis, follow-up began at date of sample collection and ended at the earliest of death, migration from Olmsted County, or 12/31/2016. The individual abstracting information on hospitalization for infection was blinded to the results of MBL screening.Chi-square tests were used to assess associations between MBL status and demographic characteristics. Cox regression models were used to determine association with risk of hospitalization with infection accounting for the competing risk of death using Fine Gray models.Results: We screened for MBL in 1045 Olmsted County residents age 40 and older. Of these, 984 (94%) had interpretable results. 119 of these 984 (12%) had a clonal B-cell population detected including 106 (11%) with CLL phenotype (CD5, CD19, CD20 [dim], CD23, kappa or lambda light chain restriction [dim]).This analysis focused on the 106 individuals with CLL-like MBL clones (mean age 69 years, 55% male) and the 865 individuals with normal immunophenotype (mean age 61 years, 40% male).The presence of CLL phenotype MBL was strongly associated with age. MBL was detected in 3% of patients age 40-49 years, 7% of those 50-59, 10% of those 60-69, 20% of those 70-79, and 27% of those age 80+ (p<0.001). MBL was also more common among men (women 8%; men 14%; p=0.003).After a median follow-up of 7 years from biobank enrollment, 76 of the 971 participants were hospitalized with infection in Olmsted County at least once. The estimated cumulative incidence of infections at 7 years was 19% for LC MBL and 9% for those without MBL (Figure). The most frequent site of infections for which these individuals were first hospitalized were pneumonia (14 individuals; 18%), cellulitis (20 individuals; 26%), urinary tract infection (21 individuals; 26%), and blood stream infection (6 individuals; 8%). An association between LC MBL and hospitalization with infection was observed with the unadjusted HR for hospitalization with infection among the 106 Olmsted County residents with LC MBL relative to the 865 Olmsted County residents with normal immunophenotype is 2.41 (95%CI: 1.39-4.19; p=0.002). After adjusting for age and sex, the HR is 1.65 (95% CI: 0.95-2.88; p=0.08).Conclusions:We report one of the first studies to systematically explore the relationship between LC MBL and the risk of serious infection. It appears that individuals with LC MBL may be at increased risk for serious infection. If this observation is confirmed, it would suggest that 5-10% of adults over age 40 (6-12 million U.S. adults) have a largely unstudied condition with potentially serious health implications. [Display omitted] DisclosuresShanafelt:Hospira: Research Funding; AbbVie: Research Funding; Celgene: Research Funding; Pharmacyclics: Research Funding; Jannsen: Research Funding; GlaxoSmithKline: Research Funding; Genentech: Research Funding. Kay:Gilead: Research Funding; Agios: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Research Funding; Tolero Corporation: Research Funding. Parikh:Pharmacyclics: Research Funding; AstraZeneca: Honoraria; Pharmacyclics: Honoraria.

Monoclonal B-cell lymphocytosis in blood donors in Turkey

ABSTRACTObjectives: Monoclonal B-cell lymphocytosis (MBL) is a precursor state of chronic lymphocytic leukemia (CLL) with peripheral lymphocytosis below 5 × 109/l. The diagnostic criteria exclude the presence of lymphadenopathy, organomegaly, infections, autoimmune diseases or any sign of a lymphoproliferative disorder. This prospective study was designed in order to evaluate the frequency of MBL in blood donors in Turkey.Methods: The diagnosis of MBL was identified by flow cytometry method based on the International Familial CLL Consortium Report. A total of 999 volunteers [median age 34 (18–78) years; male/female: 705/294] were included in the study.Results: Monoclonal B-cell lymphocytosis was demonstrated in 18 cases (1.8%). A total of 16 cases (1.6%) was evaluated as CLL-like MBL, while 2 (0.2%) had a non-CLL-like phenotype. The subjects were divided into three groups according to age, as <40 years, 40–60 years and >60 years. The prevalence of MBL was 1.1% below 40 years, 0.6% between 40 and 60 years and 0.1% in cases over 60 years, without statistical significance (p > 0.05).Discussion: The sensitivity of the flow cytometry method is essential and may be responsible for the variations in the prevalence of MBL in different populations which can also be attributed to study design, higher detection rates in the elderly and families with genetic predisposition to CLL.Conclusion: Large population-based studies and standardized laboratory methods are needed to determine the potential risk factors of progression to CLL, including molecular markers and genetic profile.