VH Usage Research Articles

Antibody repertoire development in fetal and neonatal piglets: XXI. Usage of most VH genes remains constant during fetal and postnatal development

Usage of variable region gene segments during development of the antibody repertoire in mammals is unresolved in part because of the complexity of the locus in mice and humans and the difficulty of distinguishing intrinsic from extrinsic influences in these species. We present the first vertical studies on VH usage that spans the fetal and neonatal period using the piglet model. We tracked VH usage in DNA rearrangements and in VDJ transcripts throughout 75 days of gestation (DG) in outbred fetuses, thereafter in outbred germfree and colonized isolator piglets, isolator piglets infected with swine influenza and in conventionally reared nematode-infected adults. Seven VH genes account for >90% of the pre-immune repertoire which is the same among tissues and in both transcripts and DNA rearrangements. Statistical modeling supports the view that proportional usage of the major genes remains constant during fetal life and that postnatal usage ranking is similar to that during fetal life. Changes in usage ranking are developmental not antigen dependent. In this species exposure to environmental antigens results in diversification of the repertoire by somatic hypermutation of the same small number of VH genes that comprise the pre-immune repertoire, not by using other VH gene available in the germline. Therefore in swine a small number of VH genes shape the antibody repertoire throughout life questioning the need for extensive VH polygeny.

Selection of Individual VH Genes Occurs at the Pro-B to Pre-B Cell Transition

B cells are subjected to selection at multiple checkpoints during their development. The selection of Ab H chains is difficult to study because of the large diversity of the CDR3. To study the selection of individual Ab H chain V region genes (V(H)), we performed CDR3 spectratyping of ∼ 75-300 rearrangements per individual V(H) in C57BL6/J mice. We measured the fraction of rearrangements that were in-frame in B cell DNA. We demonstrate that individual V(H)s have different fractions of in-frame rearrangements (IF fractions) ranging from 10 to 90% and that these IF fractions are reproducible in different mice. For most V(H)s, the IF fraction in pro-B cells approximated 33% and then shifted to the nearly final (mature) B cell value by the cycling pre-B cell stage. The frequency of high in-frame (IF) V(H) usage increased in cycling pre-B cells compared with that in pro-B cells, whereas this did not occur for low IF V(H)s. The IF fraction did not shift as much in BCR-expressing B cells and was minimally affected by L chain usage for most V(H). High IF clan II/III V(H)s share more positively charged CDR2 sequences, whereas high IF clan I J558 CDR2 sequences are diverse. These data indicate that individual V(H)s are subjected to differential selection, that V(H) IF fraction is mainly established through pre-BCR-mediated selection, that it may operate differently in clan I versus II/III V(H)s, and that it has a lasting influence on the Ab repertoire.

Human recombinant antibodies againstTrypanosoma cruziribosomal P2βprotein

Patients with chronic Chagas' Heart Disease (cChHD) develop an antibody response that is suspected to be involved in the cardiac pathogenesis. The response against Trypanosoma cruzi ribosomal P proteins is of particular interest, as these antibodies can cross-react with host cardiac receptors causing electrophysiological alterations. To better understand the humoral anti-P response we constructed a single-chain variable fragment library derived from a cChHD patient. The variable heavy and light regions were amplified from bone-marrow RNA and subcloned into the vector pComb3X. The phage library was subsequently panned against T. cruzi ribosomal P2β protein (TcP2β). We obtained 3 different human recombinant antibodies that specifically reacted with TcP2β in ELISA and Western blots. Two of them reacted with the C-terminal region of TcP2β, peptide R13, as the recombinant autoanti-P antibodies from Systemic Lupus Erythematosus (SLE) patients. Interestingly, the third one was specific for TcP2β but did not recognize R13, confirming the specific nature of the anti-P response in Chagas disease. Neither sequence nor VH usage similarities between Chagas and SLE anti-P autoantibodies were observed. Herein, the first human mAbs against TcP2β have been obtained and characterized showing that the humoral anti-P response is directed against the parasite and does not include an autoimmune component.

HLA-Dependent Immune Selection Pressure on the Idiotype Is Predominantly Driven by Somatic Hypermutation In Malignant Lymphoma but Also Modulates Vh Usage In Normal B Cells

AbstractAbstract 3132The idiotype (Id) of malignant lymphomas is a tumor-specific antigen and has been evaluated for active immunotherapy predominantly in follicular lymphoma (FL). We have previously described “reverse immunology” evidence that HLA class I-dependent and hence presumably T-cell mediated selection pressure restricts the growth of malignant FL clones with comparatively highly immunogenic Ids (Strothmeyer et al., Blood, epub 2010). This effect was mostly attributable to the Id CDRs. We therefore hypothesized that somatic hypermutation, a constitutively active process in FL, is the mechanism that creates immunogenic Id epitopes and enables T-cell mediated immunosurveillance. To test this hypothesis, we analyzed Id of FL that utilized the same Vh gene but arose in individuals with different HLA types (IGHV3-23*01, n=9 patients: IGHV3-7*01, n=3). For every represented HLA type, an “immunogenicity landscape” mapping was performed by plotting the ten most immunogenic peptides of the germ-line Vh sequence in comparison to FL Id peptides in the order of their HLA binding strength as predicted by the BIMAS algorithm for the respective patient. Neither changes in the order of peptides nor major differences in their binding scores were observed. Parallel plotting of Vh-related Ids from different HLA types revealed novel peptides with higher binding scores within and in addition to the ten highest ranking epitopes (Figures). Comparisons of these peptides with the germ-line and the index patient's sequence directly demonstrated that somatic hypermutation creates peptides that would have strongly bound to HLA type of the index patient but were immunologically neutral in the patient of origin. Occurrence of such highly immunogenic peptides by somatic hypermutation would hence not be tolerated by an FL patient's immune system. To explore whether this mechanism also operates in other lymphoma types, we analyzed predicted HLA-binding Id peptides from mantle cell (n=20) and marginal zone (n=12) lymphomas. Like in FL, the median sum of the 20 peptides with the highest BIMAS scores were to various degrees less immunogenic on the autologous HLA type than on allogeneic HLA types (ratio of autologous to allogeneic BIMAS sum scores: FL: 0.63; MCL: 0.78; MZL: 0.87). In subanalyses of the CDR, these differences were observed only in FL and MCL but not in MZL (CDR1: FL 0.40, MCL 0.55. MZL 1.39; CDR2: FL 0.25, MCL 0.36; MZL 1.54: CDR3: FL 0.43, MCL 0.53, MZL 1.28).To investigate whether HLA-dependent immunosurveillance acts on normal B-cell receptors, we compared BIMAS sum scores of 96 non-clonal Ids present in diagnostic biopsies of 29 FL and MCL patients. These Ids represent bona fide contaminating, healthy B cells. No significant differential immunogenicity existed for the entire Vh sequences or individual CDR regions, regardless of their mutational status. We therefore randomly sequenced B-cell receptors from two mouse strains with an identical B6 genetic background but a congenic H-2 complex (C57BL/6ByJ: H-2b; 422 sequences; B6-H2d/bByJ: H-2d; 412 sequences). In these SPF-bred mice, 61% and 71% of sequences, respectively, were unmutated. Significantly higher immunogenicity was observed in the FR1-3 regions of C57BL/6ByJ compared to B6-H2d/bByJ Ids on H-2kd (p=0.04). Also, several Vh genes were significantly (Fisher's exact test) less frequent in mice expressing the MHC type with stronger binding to Id-derived peptides of the corresponding germ-line Vh sequence. Overall, the ratio of predicted MHC binding strength of the 20 highest scoring peptides from 59 represented germ-line Vh genes correlated to the relative frequency of representation of these genes in the peripheral B-cell repertoire (p=0.016, Pearson correlation). Collectively, these results indicate that somatic hypermutation is the predominant mechanism that enables T-cell mediated control of malignant B-cell clones in FL but possibly also MCL on the basis of the HLA binding of Id-derived peptides. In addition, HLA binding strength of germ-line-encoded Vh peptides appears to exert a subtle modulation of the primary B cell repertoire by MHC class I-restricted T cells. These findings strengthen the theoretical basis of active Id-directed immunotherapy of B-cell lymphomas with mutated antigen receptors. In addition, they may also lead to a novel explanation for the association of HLA type with aberrant functions of the nonmalignant immune system. [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Antibody Repertoire Development in Fetal and Neonatal Piglets. XI. The Relationship of Variable Heavy Chain Gene Usage and the Genomic Organization of the Variable Heavy Chain Locus

In this study, we have mapped the 3' H chain V region (V(H)) genes and those in the H chain diversity, H chain joining, and 5' portion of the H chain constant locus. We show that swine possess only two functional H chain diversity segments and only one functional H chain joining segment. These data help to explain more than a decade of observations on the preimmune repertoire of this species and reveal the vulnerability of swine to natural or designed mutational events. The results are consistent with earlier studies on the region containing Enh, Cmu, and Cdelta while revealing that the ancestral IgG3 is the most 5' Cgamma gene. We also observed a recent duplication ( approximately 1.6 million years ago) in the V(H) locus that contains six of the seven V(H) genes that comprise 75% of the preimmune repertoire. Because there are no known transfers of immune regulators or Ags that cross the placenta as in mice and humans, fetal V(H) usage must be intrinsically regulated. Therefore, we quantified V(H) usage in fetal piglets and demonstrated that usage is independent of the position of V(H) genes in the genome; the most 3' functional V(H) gene (IGHV2) is rarely used, whereas certain upstream genes (IGHV14 and IGHV15) are predominately used early in fetal liver but seldom thereafter. Similar to previous studies, three V(H) genes account for 40% of the repertoire and six for approximately 70%. This limited combinatorial diversity of the porcine V(H) repertoire further emphasizes the dependence on CDR3 diversity for generating the preimmune Ab repertoire of this species.

BMI1, the Polycomb-Group Gene, Is Recurrently Targeted by Genomic Rearrangements in Progressive B-Cell Leukemia/Lymphoma.

Abstract 1099Poster Board I-121The 10p11 chromosomal site is recurrently affected by genomic abnormalities in B cell leukemia/lymphoma, but the molecular consequences of these aberrations remain unknown. We have collected three cases (2 female, 1 male; 67-69 years) of chronic lymphocytic leukemia (CLL) with a novel IGH-mediated t(10;14)(p11;q32) (#1 and 2) or its IGL variant t(10;22)(p11;q11) (#3), and one case of blastic mantle cell lymphoma (MCL) with a complex t(11;14)-positive karyotype including add(10)(p12) (#4). Case 1 showed unmutated VH genes and usage of VH3-21/D1-26/JH6. Cases 2 and 3 revealed mutated VH genes and usage of VH3-21/D1-14/JH4 and VH3-11/D4-4/JH6, respectively. In cases 1 and 2 with a monoallelic loss of RB1, the t(10;14)(p11,q32) was found as a secondary change at time of CLL progression/Richter transformation observed 148 and 50 months after diagnosis, respectively. In case 3, the sole t(10;22)(p11;q11) was identified at time of CLL diagnosis. All three patients died from disease progression 37-149 months after diagnosis. Of note, both patients with t(10;14) died from refractory disease 1 and 3 months after CLL progression/transformation and genetic detection f t(10;14). The patient #3 did not require therapy, but died from septic shock 37 months after diagnosis, and autopsy revealed diffuse and massive lymph node and spleen involvement. The patient with MCL (#4), 67 years old man with a previous history of prostatic adenocarcinoma and CLL, developed secondary central nervous system liesions and died 40 months after diagnosis of MCL. Extensive FISH studies of t(10;14) and t(10;22) mapped the 10p11 breakpoint in the region of the BMI1 locus. SNP array analysis of case 4 complemented by FISH identified amplification of the 10p11 region covering BMI1. Immunostaining with anti-BMI1 serum performed in 2 available cases (#2 and 3) showed expression of the BMI1 protein by neoplastic cells. This approach, however, did not allow to estimate whether the level of BMI1 expression in these cases was higher than in control CLL cases. BMI1 (B-cell-specific Moloney murine leukemia virus integration site 1) is a member of the Polycomb group of genes that are important epigenetic chromatin modifiers with an essential role in embryogenesis and the maintenance of adult stem cells. BMI1 was first identified as a protooncogene that cooperates with c-myc in the generation and development of mouse pre B-cell lymphomas. The BMI1 protein is a component of Polycomb repressive complex1 (PRC1), one of two multiprotein PRCs that maintain cell identity by gene suppression. The gene plays an important role in self-renewal of hematopoietic and neural stem cells. Multiple lines of evidence implicate BMI1 and other Polycomb genes in tumorigenesis. Among others, an aberrant expression of BMI1 has been observed in a wide spectrum of cancers and usually correlated with unfavourable clinical outcome. BMI1 is one of the genes marking the ABC-type signature of DLBCL, associated with a poor prognosis. High levels of BMI1 mRNA/protein were also detected in CLL, MCL, MM and HL. In some MCLs, overexpression of BMI1 correlated with genomic amplification of the BMI1 gene detected by aCGH in 12-24% of analysed cases (Jares and Campo, 2008). BMI1 has been shown to contribute to cell cycle regulation and senescence by acting as transcriptional repressor of the INK4a-ARF tumor suppressors. Despite the wealthy information on BMI1 contributing to a variety of tumors, molecular mechanisms underlying deregulation of BMI1 in neoplasms and functional consequences of these events remain elusive.In summary, we show for the first time that BMI1, a postulated lymphoma-related oncogene, is recurrently targeted by IG-mediated chromosomal translocations in CLL and confirm its amplification in MCL. We found that in both cases with t(10;14)/IGH-BMI1, the translocation was acquired during clinical transformation of CLL initially harboring the del(13q)/RB1. The adverse prognostic impact of BMI1 aberrations in all four collected cases is reflected by a constantly aggressive clinical course of disease and short survival of the affected patients (1-50 months). In this regard, further molecular studies of the BMI1 pathway and its downstream partners are necessary to develop novel therapeutic approaches targeting this oncogene in human cancers. DisclosuresNo relevant conflicts of interest to declare.

Duodenal and nodal follicular lymphomas are distinct: the former lacks activation-induced cytidine deaminase and follicular dendritic cells despite ongoing somatic hypermutations

Although most follicular lymphomas are believed to be of nodal origin, they sometimes originate from the duodenum. We have reported that the latter differ from nodal follicular lymphomas in having lower clinical stages and uniformly low histological grades, along with variable region of immunoglobulin heavy chain gene (VH) usage that is more similar to mucosa-associated lymphoid tissue (MALT) lymphomas. Little is known, however, about whether they possess other characteristics of nodal follicular lymphomas, particularly ongoing mutations with follicular dendritic cells. We examined 17 cases for which PCR identified the monoclonal bands of the immunoglobulin gene. The duodenal cases showed ongoing mutations, but they lacked activation-induced cytidine deaminase (AID) expression, a statistically significant difference from the nodal cases (P<0.001), and their follicular dendritic cell networks were disrupted. Moreover, not only were VH deviations observed but also they used very restricted VH genes. Although the mechanisms of ongoing mutation without AID and follicular dendritic cell were not clarified, restricted VH usage strongly suggested that antigen stimulation was involved, and that was similar to MALT lymphomas. In conclusion, duodenal follicular lymphomas were shown to be unique, in that they had ongoing hypermutations such as nodal cases, but the mechanisms involved in the hypermutation were quite different; furthermore, restricted VH usage suggested a strong similarity to the antigen-dependent origin of MALT lymphomas.

Majority of Children With Type 1 Diabetes Produce and Deposit Anti-Tissue Transglutaminase Antibodies in the Small Intestine

OBJECTIVEAnti-tissue transglutaminase (TG2) antibodies are the serological marker of celiac disease. Given the close association between celiac disease and type 1 diabetes, we investigated the production and deposition of anti-TG2 antibodies in the jejunal mucosa of type 1 diabetic children.RESEARCH DESIGN AND METHODSIntestinal biopsies were performed in 33 type 1 diabetic patients with a normal mucosal architecture: 14 had high levels (potential celiac disease patients) and 19 had normal levels of serum anti-TG2 antibodies. All biopsy specimens were investigated for intestinal deposits of IgA anti-TG2 antibodies by double immunofluorescence. In addition, an antibody analysis using the phage display technique was performed on the intestinal biopsy specimens from seven type 1 diabetic patients, of whom four had elevated and three had normal levels of serum anti-TG2 antibodies.RESULTSImmunofluorescence studies showed that 11 of 14 type 1 diabetic children with elevated levels and 11 of 19 with normal serum levels of anti-TG2 antibodies presented with mucosal deposits of such autoantibodies. The phage display analysis technique confirmed the intestinal production of the anti-TG2 antibodies; however, whereas the serum-positive type 1 diabetic patients showed a preferential use of the VH5 antibody gene family, in the serum-negative patients the anti-TG2 antibodies belonged to the VH1 and VH3 families, with a preferential use of the latter.CONCLUSIONSOur findings demonstrate that there is intestinal production and deposition of anti-TG2 antibodies in the jejunal mucosa of the majority of type 1 diabetic patients. However, only those with elevated serum levels of anti-TG2 antibodies showed the VH usage that is typical of the anti-TG2 antibodies that are produced in patients with celiac disease.

Immunoglobulin Heavy Chain (IgH) Gene Rearrangement in Egyptian Precursor B-Acute Lymphoplastic Leukemia - Implication for Assessment of Minimal Residual Disease.

The level of MRD determined with the use of PCR based techniques is the most reliable prognostic factor in therapy of ALL. In contrast to the western countries, molecular based techniques of MRD is still not included in routine assessment of ALL therapy effectiveness in Egypt. Therefore the aim of this study was early detection of MRD in precursor B-cell neoplasm to correlate it with the known prognostic factors, to assess the applicability gene scan(GS)for the detection of MRD together with assessment if there features indicating the existence of Egyptian specific characterization for IgH rearrangement. The study was conducted on 33 Egyptian patients(16 children and 17 adults)with precursor-B-ALL as confirmed by immunophenotyping. Bone marrow samples were taken on diagnosis and after completion of induction treatment. Additional 14 samples from 6 patients were collected from HMDS, Leeds General Infirmary, Leeds, UK to compare the results of gene scan and four color flow cytometry (FC) with ASO RQ PCR technique as a reference method used in the MRD detection. MRD detection was done for these cases using GS. Presentation samples DNA were amplified using Vh-Jh Biomed -2 multiplex primer sets. GS was done to the fluorescent PCR product to detect the distinct size of this product at presentation and the follow up samples. ASO RQ PCR was done for some cases as a reference method to compare it s results with FC and GS. All cases were in clinical remission after completion of induction treatment. When monitored for MRD, only 56.3% of children and 23.5% of adults found to be in true molecular remission. The MRD positivity in children in our study(62.5%)is higher than the Western studies using either FC, sequence-based techniques or heteroduplex technique. On the other hand, the MRD positivity in adult ALL(78.2%)in our study was comparable to the other Western studies. It is found that there is a very high significant concordance between the presence of MRD at post-induction and the occurrence of relapse in both childhood (p=0.000) and adult ALL (p=0.002). There was no significant correlation between the conventional prognostic criteria and the existence of MRD apart from percentage of peripheral blood at day 7 (p=0.009) in childhood ALL. GS results were compared with four color FC, ASO RQ PCR. Sensitivity of GS in detection of MRD in precursor B-ALL is 75% compared with ASO RQ PCR. There was complete VH-JH rearrangement in all patients. It is noticed that the most frequently used VH gene segments in our study belongs to VH3 family in both children (56.3%) and adult (64.7%). This is followed by VH6(25%), VH1(18.75%), and VH 4(12.5%)in children, and by VH1(29.41%), and VH2, and VH4 together covering 11.76% in adult group. The prevalence of VH3 family usage noticed in this study is in concordance to the most of published studies. However, the frequency of other VH other than VH3 segment usage varied from the Western studies. In conclusion, MRD monitoring in precursor-B-ALL patients is a powerful independent prognostic factor. A wide scale study on Egyptian precursor B-ALL patients to define the frequency of VH usage and the presence of other rearrangements that may characterize MRD kinetics and clonal evolution for stratification of treatment protocol.

Analysis of Immunoglobulin Gene Mutation Status in Lymphoplasmacytic and Splenic Marginal Zone Lymphomas with Bone Marrow Infiltration.

Splenic Marginal-Zone lymphomas (SMZL) and Lymphoplasmacytic lymphomas (LPL) correspond to entities that shared clinical, morphological and immunohistochemical features and are not always easy to discriminate. Immunoglobulin variable heavy chain gene (VH) usage and somatic mutation pattern were analyzed to clarify the relationship and the pathogenesis of these 2 entities.Bone marrow frozen samples from 27 patients, 16 LPL and 11 SMZL, were studied. B-cell clonality was first analysed using the standard PCR method with the Biomed 2 primers. Informative PCR products were then purified, sequenced and analyzed on IMGT and Ig-Blast websites.Overall, median rate of somatic mutations was 9% in LPL and 4% in SMZL (p=0.013).All cases of LPL were mutated. Mutation rate was always higher than 5%. A preferential usage of VH3 gene was observed in 13/16 cases (80%), with a predominance of VH3–23 and VH3–74, both representing 60% of cases. VH4 gene was used only in 2/16 cases (13%). Regarding JH usage, a predominance of JH4 gene rearrangement was observed in 11/16 cases (69%). JH5 and JH6 were used in 20% and 13% of cases respectively.In the group of SMZL, mutation rates and usage of VH and JH genes were more heterogeneous. Thirty six percent of SMZL were unmutated and 19% had a mutation rate lower than 5%. VH3 was used in 4/11 cases (36%), VH4 in 3/11 cases (27%) and VH1 in 4/11 cases (36%). JH4 and JH6 were used in 4/11 cases (36%) and the JH5 in 1/11 cases (9%).Therefore, the profile of somatic mutations and the VH and JH segment preferentially used are different in SMZL and LPL, suggesting a different process of antigen-driven selection and of transformation of the initial B-cell clone. These findings consolidate the existence of LPL as a genuine entity, different of SMZL despite their histopathological overlaps.

D Gene Usage Predicts Clinical Outcome in Patients with Low Rai Risk Unmutated B-CLL.

Mutation status of the immunoglobulin heavy chain variable region (IgVH) in B cell chronic lymphocytic leukemia (B-CLL) is a critical prognostic tool. Although patients with unmutated (UM) IgVH genes exhibit an overall shorter survival than those with mutated (M) IgVH genes, considerable heterogeneity in clinical progression exists among UM B-CLL patients. The goal of this study was to evaluate UM CLL patients (n=215) in a large B-CLL cohort for Ig V, D, and J gene usage and relevant clinical parameters to identify Ig molecular features in addition to UM vs. M status that have prognostic value. Consistent with the literature, the most commonly expressed IgVH gene in our UM B-CLL cohort was VH 1–69 (69/215). We first evaluated D and J usage in VH 1-69 vs. non-VH 1–69 UM patients. The factors that were significantly different between VH1–69 vs. non-VH 1–69 cohorts were JH6 usage (p=0.0014), D3–3 usage (p=0.0025), and the combination of JH6 and D3–3 usage (p=0.0002). We then examined potential associations between patient time to treatment (TTT) and specific IgVH molecular features. Although there was a trend that VH 1–69 patients exhibited a shorter TTT than non-VH 1–69 patients, the association did not reach statistical significance (p=0.06). When all UM patients were instead grouped on the basis of D and J usage, JH6 usage was not significantly associated with TTT, but D3–3 usage, irrespective of VH or JH usage, significantly correlated with shorter TTT (p=0.005). Of interest, when JH6 patients were excluded from the analysis, differences in TTT between those with and without D3–3 usage were particularly pronounced (p=0.011).We next explored whether a specific D3–3 reading frame (RF) is associated with TTT. Within the group of D3–3 patients, we evaluated differences in TTT between those with RF 2 (n=38) vs. RF 3 (n=19) but did not study RF1 patients due to small numbers (n=6). Comparison of D3–3/RF 3 patients (n=19) with all other UM patients (n=190), did not reveal a significant difference in TTT, however, there was a significant difference (p=0.012) in TTT between D3–3/RF 2 patients (n=38) and all other UM patients (n=171).Rai risk was still the best overall prognostic factor, and was the only significant factor (p<0.0001) in the multivariable (MV) setting for TTT using the entire UM cohort. However, when we categorized patients by both Rai risk (low vs. intermediate/high) and D3–3 usage, the most pronounced differences for TTT were observed based on D3–3 usage in the low Rai risk = 0 patients. Thus, the D3–3 cohort within the Rai 0 risk group displayed a significantly shorter TTT than did the non-D3–3 Rai 0 risk cohort (p=.0006). In model-building approaches in the MV setting using both the stepwise and score statistic methods for Rai 0 patients, D3–3 usage was the only significant factor for TTT (p=0.0004) even when RF 2 usage, JH6 usage, and absolute mutation percentage were also considered.These data illustrate for the first time the clinical importance of D gene usage and D gene RF in disease progression in early stage UM B-CLL. Moreover, this study adds further support to the notion that there is selection for specific Ig receptors in B-CLL and that the antigenic specificity of certain receptors may be associated with aggressive disease. Finally, these data demonstrate that the prognostic utility of IgVH mutation testing goes beyond simply determining categorical IgVH mutation status.

Deviated VH4 immunoglobulin gene usage is found among thyroid mucosa-associated lymphoid tissue lymphomas, similar to the usage at other sites, but is not found in thyroid diffuse large B-cell lymphomas

It remains unclear whether or not diffuse large B-cell lymphomas of extranodal sites arise from mucosa-associated lymphoid tissue (MALT) lymphomas. We studied the clinicopathological features of MALT lymphoma and diffuse large B-cell lymphoma in the thyroid gland, with special reference to VH usage of immunoglobulin gene rearrangement, to clarify the relationships between these two types of lymphomas. In addition, t(11; 18) (q21; q21) translocation was examined by multiplex reverse transcription-polymerase chain reaction. We examined 58 patients with primary thyroid lymphoma: 31 (male seven and female 24) with MALT lymphoma and 27 (male three and female 24) with diffuse large B-cell lymphoma. Interestingly, the sequence of VH genes revealed that the two subtypes differed significantly in their use of the VH4 family (P<0.05). Of the seven MALT lymphomas, three used the VH4 family and the other four used the VH3 family, whereas eight out of nine diffuse large B-cell lymphoma used the VH3 family, one used the VH1 family, and none used the VH4 family. It was also interesting that, in one diffuse large B-cell lymphoma patient with MALT lymphoma, the diffuse large B-cell lymphoma component used the VH3 family and the MALT lymphoma component used the VH4 family. These data imply that, in a subset of cases, these two subtypes do not share a common origin and that at least some diffuse large B-cell lymphomas have a de novo origin. No t(11; 18) (q21; q21) was detected in thyroid lymphomas, which are different from MALT lymphoma of the stomach, lungs, large intestine and ocular adnexa. This strongly indicated that the presence of t(11; 18) (q21; q21) in MALT lymphoma is organ-specific.

Molecular and Clinical Analysis of a Midwest Cohort of B-CLL Patients Utilizing the Immunoglobulin VH 1-69 Gene.

The prognostic power of immunoglobulin (Ig) somatic mutation status in B cell chronic lymphocytic leukemia (B-CLL) is widely appreciated and has served as the rationale to systematically determine this molecular feature in B-CLL patients. Consistent with other reports, our study of Ig mutation status in a large cohort of B-CLL patients (n=599) found the most commonly used Ig heavy chain variable (VH) region gene was VH 1–69. The VH1–69 gene is of particular interest as there are numerous reports demonstrating that VH1–69 expressing B-CLL cells predominantly express the 51p1-like allele in an unmutated (UM) form and it is frequently associated with use of the D gene segment, D3-3; the J gene segment, JH6; and a relatively long third, complementarity-determining region (CDR3). Despite molecular definition of a commonly used form of VH1–69 in B-CLL, the clinical significance of CLL B cell usage of this prototypic form of VH1–69 remains to be determined. The goal of this study, therefore, was to perform a molecular and clinical analysis on our cohort of B-CLL patients expressing the VH1–69 gene. Our cohort consisted of 19 females and 55 males, with 89.5% expressing UM Ig VH. The 51p1-like allele was present in 75.7% of patients and the predominant D region used was D3 (64.7%). Patients in our cohort were classified by Rai risk as follows: 20 low (28.2%), 40 intermediate (56.3%), and 11 high (15.5%). For those patients with Rai stage available, analysis of specific D and J regions resulted in 16 D3-3/JH6 (26.7%); 14 D3-3/non-JH6 (23.3%); 16 non-D3-3/JH6 (26.7%); and 14 non-D3-3/non-JH6 (23.3%). Despite observing an overwhelming majority of leukemic cells with UM Ig VH, and the known relationship between mutation status and disease progression, it is interesting that our cohort included almost 30% with a low Rai risk. Of note, Ig VH mutation status did not segregate with Rai risk group or VH1–69 allele use (although few patients overall were mutated). However, an UM Ig VH status was associated with a CDR3 length >20 (p = 0.001) and with use of the JH6 segment (p = 0.003). When mutation status was analyzed in concert with specific use of the D3-3 allele, no relationship emerged; however, when this D region allele was analyzed for JH6 vs non-JH6 usage, combination of the D3-3 allele with JH6 was significantly associated with an UM Ig VH status (p = 0.004). Moreover, when J and D segment usage was analyzed in concert with Rai stage group, a significant (p = 0.019) relationship emerged between paired use of D3-3 and a JH6 segment and advanced (intermediate/high) Rai stage. Strikingly, only 1 of 18 VH1–69 patients with low Rai risk for whom D and J data were available expressed the specific combination of D3-3 and JH6. Although analysis of a larger cohort is clearly required to more formally and fully evaluate these relationships, to our knowledge, this is the first suggestion that D and J usage in VH1-69 expressing B-CLL patients correlates with advanced stages of disease. Because Ig VH usage is not believed to change over the course of disease, it is tempting to speculate that VH1–69 B-CLL patients that do not express the prototypic VH1–69 receptor may have a more favorable disease course. In summary, these data add further support to the notion that there is selection for specific Ig receptors in B-CLL and that the antigenic specificity of certain receptors may be associated with risk of progression.

Telomere Length Identifies Two Distinct Populations with Different Outcome among VH-Unmutated CLL Patients.

Introduction Telomere restriction fragments (TRF) length is a well-known prognostic indicator in CLL. Long telomeres have been associated with VH-mutated status, while VH-unmutated patients are regarded as having uniformly short telomeres. However, little is known on cases in which discordance exists between these two parameters. Patients and methods 138 B-CLL patients were analyzed for TRF length and VH mutational status. All samples were taken before the start of anti-CLL treatment. M/F ratio was 93/45. Median age was 60 years. According to Binet staging, 82 patients were A, 30 B and 26 C. CD38 and ZAP70 expression and FISH for Ch 11, 12, 13, 17, were available in 72% of patients. Median follow-up was 33 months (range 6–290). TRF length was evaluated by Southern blot as previously described (Ladetto M et al, Blood 2004). VH mutational status was evaluated by direct sequencing according to standard methods. Results VH sequencing was successful in 127 patients: 82 were VH-mutated and 45 VH-unmutated. Median TRF length was 6097bp (1465–14837). As expected VH-unmutated patients had shorter telomeres (median 4000bp) compared to VH-mutated patients (median 7399bp) (p<0.0001). A mathematical model has been employed to analyze the distribution of TRF length in VH-mutated and unmutated patients. While mutated patients had a homogeneous distribution, unmutated patients showed a bimodal distribution with no patients falling between 4137 and 4710bp (fig1a). This allowed to discriminate a larger population (26 patients) with very short TRF length (concordant patients), and a smaller (19 pts) with a TRF length superimposable to that of VH-unmutated patients (p=0.21) (discordant patients). Concordant and discordant patients had similar patterns of VH usage and similar levels of homology (H) to the germline IgH sequence (i.e. H=100% vs H<100% and >99% vs H<99% and >98%). In addition they showed no difference for all the available (previously mentioned) biological and clinical parameters. However the two population had significant differences in terms of clinical outcome: 5-year PFS was 22% in concordant patients and 55% in discordant (p<0.05) (fig1b). Moreover, only 1 patient has already died among discordant patients as opposed to 9 among concordant (fig1c). Of note, the outcome of discordant patients was not significantly different from that of VH-mutated patients. The role of telomere length as survival predictor was further supported by performing univariate and multivariate analysis indicating that TRF length is the most powerful prognostic indicator among those considered (age, sex, Binet, CD38, ZAP70, FISH and mutational status). Conclusion VH-unmutated patients are highly heterogeneous and this heterogeneity can be revealed through evaluation of TRF length. [Display omitted]

Molecular Analysis of Immunoglobulin Genes in Primary Intraocular Lymphoma

To analyze somatic hypermutations in clonally rearranged IgH chain variable (V) genes of primary intraocular lymphoma (PIOL), to identify the differentiation stage of B-PIOL cells. Sixteen cases of PIOL were diagnosed on the basis of morphology and immunohistology. In six patients, simultaneous cerebral lymphomatous involvement was known; stereotactic biopsy specimens were investigated in three cases. A polymerase chain reaction (PCR) was performed on DNA extracted from vitrectomy specimens or from paraffin-embedded sections, to amplify the clonally rearranged heavy-chain immunoglobulin (IgH) genes. The isolated PCR products were sequenced and compared with published VH germ-line segments to determine the VH usage and number of somatic mutations in the complementarity-determining region (CDR)2 and framework region (FR)3. All tumors exhibited clonal IgH rearrangements. Of the eight sequenceable cases, four had the VH4-34 gene segment, two the VH3-23, one the VH3-7, and another the VH3-30. The pattern of somatic mutations indicated selection of PIOL cells for expression of a functional antibody. The mean frequency of somatic mutations detected for the IgH gene was very high (14.5%). In three oculocerebral lymphomas, the identical B-cell clone was demonstrated in ocular and cerebral tissues. The data suggest that PIOLs (1) are derived from mature B-cells that have undergone the germinal center reaction and (2) are closely related to primary cerebral nervous system lymphoma (PCNSL), due to their high mutation frequency of VH region genes. The close relationship between PIOL and PCNSL is underlined by demonstration of the same VH segment (VH4-34) in three of six cases of oculocerebral lymphoma.

The Restricted VH-Gene Usage Is of Prognostic Value in B-Cell Chronic Lymphocytic Leukemia.

In B-cell chronic lymphocytic leukemia (B-CLL) the mutation status of the immunoglobulin variable heavy chain gene (VH) is known as a prognostic factor. We have investigated if specific VH-gene usage is of additional prognostic importance regarding survival. Peripheral blood samples from 147 B-CLL patients were analysed for VH usage. Recombinations occurring in at least 5% of cases were studied in depth. The most frequently used VH-gene segments were VH1-69 (10.9%), VH3-7 (7.5%), VH3-30 (6.8%), VH4-34 (6.8%), VH3-21 (6.1%), VH3-23 (6.1%), and VH3-33 (5.4%). The VH gene usage was compared with mutation status, cytogenetic abnormalities and survival. Comparison with age matched controls reveals the restricted VH gene usage in B-CLL. VH gene usage showed a distinct prognostic value (p=0.01) when the patients using VH genes with bad prognosis were grouped together (VH1-69, VH3-21, VH3-23 and VH3-33; 43% of these patients died) and were compared with the patients using VH genes with a relatively good prognosis (VH3-7, VH3-30 and VH4-34; mortality rate of only 13%). The prognostic significance holds true when all patients were included (p=0.03). Also the mutation status (p=0.04) and cytogenetics (p=0.03) showed a prognostic significance. The VH gene usage did not correlate with mutation status, nor with cytogenetics. On the contrary mutation status and cytogenetics were strongly correlated (p<0.00001). These findings are highly suggestive for VH gene usage to offer additional prognostic information to the other well established prognostic parameters. In conclusion, a bias to the specific VH gene segments involved in B-CLL supports the concept that B-CLL arises from B cells driven by specific antigens/superantigens which is different from a stochastic event in the elderly B-cell population. Moreover, the immunoglobulin specificity reveals specific subgroups with differing prognosis.

Short consensus probes with 3′-minor groove binder of the immunoglobulin heavy-chain gene for real-time quantitative PCR in B-cell non-Hodgkin lymphomas

We used 3′-minor groove binder (MGB) technology to develop consensus fluorogenically labeled probes of the immunoglobulin heavy-chain (IgH) gene for detecting minimal residual disease (MRD) in B-cell non-Hodgkin lymphoma (B-NHL). Sequence data from 59 patients with B-NHLs revealed a narrow consensus region as a result of somatic hypermutations and variable VH usage, indicating that it would be difficult to design ordinary non-MGB probes. MGB probes, characterized by shorter length but higher melting temperature, are more suitable for this situation than ordinary non-MGB probes. In fact, the present data indicated that about 20% more cases were detectable with MGB probes (34/59, 57.6%) than with the non-MGB probes (23/59, 39.0%) designed by Donovan et al. MGB technology is useful for the design of consensus fluorogenically labeled probes of the IgH gene for detecting MRD.

Analysis of V(H) genes rearranged by individual B cells in dermal infiltrates of patients with mycosis fungoides.

In patients with cutaneous T cell lymphomas such as mycosis fungoides B cells can frequently be detected in the lymphocytic dermal infiltrate. To analyse their immunoglobulin heavy chain gene repertoire, single B cells were obtained from tissue sections of two typical patients with mycosis fungoides using hydraulic micromanipulation followed by specific amplification of the respective gene segments by single-cell polymerase chain reaction (PCR) technique. A total of 21 V(H)DJ(H) genes was sequenced. From each individual B cell a single productive V(H)DJ(H) rearrangement was obtained. There was no clonal relationship detected between any of these rearrangements suggesting polyclonality of the infiltrating B cells. The representation of V(H) families was in accordance with the germ-line complexity. A remarkably high number of V(H) genes (5/13 in patient 1; 3/8 in patient 2) was completely or nearly germ-line-identical. Five of seven V(H)4 family genes were nearly unmutated. On the other hand, most of the V(H)3 gene family members were somatically mutated in an antigen-driven manner. The proportion of germ-line-identical V(H) genes, the usage of individual V(H), D, J(H) gene elements, and the pattern of somatic mutations found in the B cells infiltrating skin lesions of patients with mycosis fungoides resembles the peripheral blood repertoire, suggesting a bystander role of these cells.

Systematic analysis of sequences of anti-DNA antibodies--relevance to theories of origin and pathogenicity.

Sequence analysis of anti-DNA antibodies is important in determining the molecular features which distinguish potentially pathogenic antibodies from those which are less likely to be pathogenic. Previous analysis of murine anti-DNA antibody sequences suggested that particular murine immunoglobulin genes are used preferentially to encode such antibodies and that somatic mutations to arginine, asparagine and lysine may be important in the creation of DNA binding sites. In this paper, a systematic analysis of published human anti-DNA sequences shows no strong evidence for preferential usage of particular human V(H) or V(L) genes in anti-DNA antibodies. Somatic mutations in IgG and IgA antibodies are clustered in the complementarity determining regions (CDRs) due to the effect of antigen drive. This process contributes to an excess of arginine, asparagine and lysine residues in these CDRs, some of which are likely to play an important role in binding to DNA. Computer modeling and in-vitro expression experiments are likely to help define the roles played by these residues in antigen binding and pathogenicity more clearly.

VH usage and somatic hypermutation in peripheral blood B cells of patients with rheumatoid arthritis (RA).

The human antibody repertoire has been demonstrated to have a marked V-gene-dependent bias that is conserved between individuals. In RA patients, certain heavy chain V genes (VH) have been found to be preferentially used for encoding autoantibodies. To determine if such preferential use of VH genes in autoantibodies is associated with a general distortion of the V gene repertoire in RA patients, the VH composition of peripheral blood B cells was analysed among four RA patients and four age- and sex-matched healthy controls. Usage of individual VH genes (eight VH3 and three VH4 genes tested by hybridization with a set of gene-specific oligonucleotide probes) was highly biased among RA patients, but no evidence of a distortion in the bias was observed compared with healthy controls. However, the occurrence of somatic mutations in these VH genes (estimated by differential hybridization with motif-specific oligonucleotide probes targeted to CDR and FR of the tested genes, and by DNA sequence analysis) was strikingly different between patients and healthy subjects. The number of VH3 rearrangements that had accumulated somatic mutations and the number of mutations per rearrangement were significantly elevated in three of the four RA patients. A slight but not significant elevation in mutations among rearranged VH4 genes was also observed in these patients. These data suggest that although usage of individual VH genes among peripheral blood B cells is not affected by the disease, the autoimmune process may involve a significant fraction of the B cell compartment.