B-cell Small Lymphocytic Lymphoma Research Articles

The impact of peripheral blood cell ratios in dogs with diffuse B-cellsmall lymphocytic lymphoma treated with CHOP protocol

In this study, pre-chemotherapy hematological values of 14 dogs diagnosed with diffuse B-cell small lymphocytic lymphoma were compared with the hematological data of 26 healthy dogs. Neutrophil/lymphocyte ratio (NLR), lymphocyte/monocyte ratio (LMR), platelet/lymphocyte ratio (PLR), and platelet/neutrophil ratio (PNR) were evaluated between two groups. Anemia and an increased total leukocyte count were observed in dogs with lymphoma compared to healthy ones. The PNR value was found to be significantly lower in dogs with lymphoma. It was concluded that more comprehensive studies are needed to clearly understand the diagnostic and prognostic importance of hematological parameters in B-cell small lymphocytic lymphoma of dogs.

S2018 Primary Small Lymphocytic B-cell Lymphoma of Gallbladder Mimicking Acute Cholecystitis

S2018 Primary Small Lymphocytic B-cell Lymphoma of Gallbladder Mimicking Acute Cholecystitis

B-cell small lymphocytic lymphoma in a free-ranging South American fur seal (Arctocephalus australis).

Lymphomas are malignant neoplasms of the hematopoietic system arising from lymphocytes with highly variable biologic behavior. B-cell small lymphocytic lymphoma (B-SLL) is a non-Hodgkin lymphoma infrequently described in domestic and wild animals. The present study describes a case of B-SLL in a free-ranging adult male Arctocephalus australis in Brazil. The main necropsy findings included poor body condition, generalized lymphadenomegaly, severe and diffuse splenomegaly, and multiple, white to yellow nodules in the kidneys and small intestine. Histologically, these organs were partially or totally effaced by neoplastic small lymphocytes arranged in sheets, with moderate anisocytosis and anisokaryosis and a low mitotic count. These cells diffusely immunolabeled for CD79α and CD20, and were negative for CD3. A diagnosis of multicentric B-SLL was established and to the authors' knowledge, it has not been previously described in this genus.

Uncommon anatomical sites and anatomopathological presentations of lymphoma in dogs

ABSTRACT: Lymphomas are the tumors most frequently associated with the death or euthanasia of dogs in most parts of the world. In dogs, they almost always occur as disseminated (multicentric lymphoma), gastrointestinal (alimentary lymphoma), or nodal mediastinal (mediastinal lymphoma) diseases. However, other uncommon presentations can occasionally occur. This study aimed to establish the prevalence of these unusual types of lymphoma and demonstrate to veterinary pathologists how they present pathologically. From a total of 100 cases of lymphoma in dogs diagnosed between 1965 and 2017, 16 cases (16/100) were considered by us as non-traditional presentations of the disease: follicular lymphoma, (5/100), peripheral T-cell lymphoma, NOS (2/100), angiocentric lymphoma (2/100), intravascular large T-cell lymphoma (2/100), lymphomatoid granulomatosis (1/100), anaplastic large-cell lymphoma (1/100), hepatosplenic T-cell lymphoma (1/100), and chronic small B-cell lymphocytic lymphoma, intermediate type (1/100). We hope that the results presented here can help veterinary pathologists to recognize such cases of “atypical lymphoma” in their diagnostic routines.

Prevalence and clinical presentation of lymphoproliferative disorder in patients with primary Sj\xf6gren\u2019s syndrome

Lymphomas are one of the serious complications of the primary Sjörgen’s Syndrome (pSS). The aim of the study was to evaluate the frequency of lymphoma in pSS. The singe-center retrospective study included 198 Caucasian patients, who met diagnostic criteria for pSS. The type of lymphoproliferative disorder was classified according to the WHO 2016 classification. The mean time of observation, after pSS diagnosis, was 48 weeks. Focus score (FS) ≥ 1 was present in 85% of the patients, and anti-SSA antibodies were detected in 84%. Rheumatoid factor was detected in 130 (65%) patients. Mean disease activity index, according to EULAR Sjörgen’s Syndrome disease activity index (ESSDAI), was 8.3 points at the moment of pSS diagnosis. Complement C3 was decreased in 14% of the patients, while 10% showed reduced complement C4. Four patients (2%) were diagnosed with a lymphoma. Most of the patients were diagnosed with mucosa-associated lymphoid tissue lymphoma (MALT), in whom the tumour was located in the parotid gland, and in one patient the stomach was involved. Finally, one patient was diagnosed with a rare B-cell small lymphocytic lymphoma located in the lungs. In this article, we present detailed characteristics of each case. In analysed population the frequency of lymphoma in the course of pSS in patients with pSS is 2%. The variety of lymphoma types in pSS patients imposes individual monitoring in each patient at every check-up visit for disease activity.

Unusual presentation for small lymphocytic lymphoma: Case report of a man with bilateral ear involvement and review of the literature

IntroductionEar involvement by non-Hodgkin lymphoma is quite rare and can be mistaken for other common lesions encountered in otolaryngology. The literature on this subject is also limited. Case summaryA 45-year-old man with bilateral ear nodules that progressed over two years. Biopsy of the right ear revealed a B-cell small lymphocytic lymphoma (SLL). The patient responded to radiotherapy well. He received an additional dose two months after the initial treatment because of a remaining nodularity on the right earlobe. After several months, he presented a new lesion on his nasal tip, for which a biopsy confirmed a lymphoma relapse. The patient was managed with oral prednisone and low-dose radiation with a favourable response. DiscussionThis case highlights the importance of including lymphoma in the differential diagnosis of ear lesions from an otolaryngology perspective. A biopsy of any lesion or nodule with an atypical course should be considered for appropriate diagnosis and management.

Impact of Incomplete Cycles and Dose Attenuation of Rituximab-Bendamustine on Survival Outcomes in Low-Grade Non-Hodgkin Lymphomas

IntroductionRituximab and Bendamustine (BR) has been shown to be effective in the treatment of indolent non-Hodgkin's lymphomas (NHLs) with an acceptable safety profile and comparable to Rituximab, Cyclophosphamide, Doxorubicin, Vincristine and Prednisolone (R-CHOP). However, patients may develop significant cytopenias after Bendamustine exposure leading managing physicians to truncate the suggested treatment course or attenuate treatment dosages. We hypothesize that this reduced treatment intensity may negatively affect treatment outcomes.MethodsWe retrospectively analysed patients who were diagnosed with indolent non-Hodgkin lymphomas (NHL) at the Singapore General Hospital from year 2000 and received BR or R-CHOP frontline. Data was locked at 31 October 2017. Histologic diagnosis was made according to published international guidelines. The safety and efficacy of BR and RCHOP as first line treatment of indolent lymphomas was analyzed. We also evaluated if truncation of immunochemotherapy cycles or dosage attenuation impacts on progression-free survival (PFS). We define patients on BR as i) BR full - having received 6 cycles of BR at 90mg/m2/day for 2 days per cycle ii) BR attenuated - received at least 6 cycles of BR at 70mg/m2/day for 2 days per cycle iii) BR truncated - received less than 6 cycles of BR. The chi-squared and Fisher's exact two-sided tests were used for comparisons between categorical variables and the t-test was used for continuous variables. Survival probabilities were calculated using the Kaplan-Meier estimator, with log-rank analysis used to compare between different groups. All analyses were performed using Stata (Statacorp, College Station, TX, USA).ResultsEighty-seven patients were evaluable of whom 47 received BR and 40 received R-CHOP upfront. Amongst patients who received BR and R-CHOP respectively, histological diagnoses were: follicular lymphoma (19.2% vs 72.5%), marginal zone lymphoma (25.5% vs 7.5%), chronic lymphocytic leukaemia / small B-cell lymphocytic lymphoma (29.8% vs 5.0%), lymphoplasmacytic lymphoma (21.3% vs 7.5%), mantle cell lymphoma (2.1% vs 5.0%) and other B-cell lymphoma not classifiable (2.1% vs 2.5%). Baseline characteristics are presented in Table 1 and treatment related toxicities are presented in Table 2. There was no significant difference in treatment emergent grades 3/4 haematological adverse events between BR and R-CHOP. More patients developed infusional reactions (17.0% vs 2.5%, p =0.04) when treated with BR compared to R-CHOP. Conversely, more patients treated with R-CHOP developed peripheral neuropathy (15.0% vs 0%, p=0.008).More patients who were treated with BR as compared to R-CHOP had treatment truncated (i.e. received less than 6 cycles) or dosages attenuated (46.8% vs 5.0%, p<0.005). The median number of cycles completed for patients who had BR treatment course truncated was 4 (interquartile range 2-4). For patients treated with BR, the reasons for treatment truncation were drug-related toxicity (17.0%), patient's decision (10.6%) and physician's decision (2.1%). 2 patients had early termination with R-CHOP treatment, 1 (2.5%) due to disease progression and another patient (2.5%) due to drug-related toxicity.With a median follow-up of 51.0 months, median PFS for patients treated with BR was 69.5 months versus 76.9 months for patients treated with R-CHOP (p=0.26). BR truncated patients had inferior PFS compared to BR full and BR attenuated patients (Median PFS = 36.5mths vs NR, p=0.01). There was no statistically significant difference in PFS between BR full and BR attenuated patients (Median PFS = 69.5 mths vs NR, p=0.25).ConclusionTreatment efficacies and haematological toxicities were comparable in our patients with indolent NHLs treated with BR or R-CHOP. Despite this, more patients treated with BR had treatment truncated prematurely. The majority of such terminations were for drug-related toxicities. We found inferior PFS in patients who received less than 6 cycles of BR. Patients who completed 6 cycles of BR but had attenuated dosages did not have inferior PFS compared to patients who received 6 cycles of BR at full dose. Our findings suggest that treatment truncation with reduced treatment intensity negatively affects survival outcomes. Patients with cytopenias should be supported or have drug dosages attenuated with the aim to complete the entire treatment course for best outcomes. [Display omitted] DisclosuresChen:Takeda: Honoraria, Other: Travel grant; Janssen: Honoraria; Celgene: Honoraria; Amgen: Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding. Goh:Novartis AG: Honoraria, Other: Non-financial support, Research Funding; Takeda: Other: Non-financial support, Research Funding.

Abstract LB-245: Immunohistochemical study of MAGI-2 expression in lymphomas and carcinomas from prostate, urinary bladder, ovary, pancreas, liver, and colon

Abstract Introduction MAGI-2 (Membrane Associated Guanylate Kinases Inverted 2) is a scaffolding protein that interacts with PTEN in shutting off the Pi3K/AKT pathway. MAGI-2 suppresses AKT by enhancing PTEN function and its protein stability. In this study, we examined the protein expression of MAGI-2 in normal tissues and various solid tumors by immunohistochemistry (IHC). Methodology An IHC study of MAGI-2 was performed on normal tissue and tumor tissues from prostate (34 cases), ovary (95 cases), urinary bladder (92 cases), pancreas (88 cases), liver (2 cases), colon (2 cases), and lymphoma (185 cases). MAGI-2 staining intensity was semi-quantitatively scored using a 0-3 scale. Percent positive rate of MAGI-2 was calculated for carcinomas from prostate, urinary bladder, ovary, pancreas, liver, colon, and lymphoma. Results In normal tissues, MAGI-2 was detectable by IHC mostly in follicle area of the tonsil or lymph node and in the cuboidal or columnar epithelium of several organs (skin, urinary bladder, breast, fallopian tube, small intestine, colon, prostate, adrenal gland, and thyroid). The protein expression of MAGI-2 was higher in tumor cells than in their adjacent normal tissues from prostate, urinary bladder, ovary, pancreas, lymph node, liver, and colon. The positive rate of MAGI-2 was 100% for invasive prostate adenocarcinoma (34/34 cases), 82% for ovarian adenocarcinoma (78/95 cases), 76 % for urinary bladder carcinoma (70/92 cases), 62 % of pancreatic adenocarcinoma (55/88 cases), 83 % for diffuse large B-cell lymphoma ( 135/163 cases), 80 % for follicular B-cell lymphoma (8/10 cases), 67% for non-Hodgkin B-cell lymphoma (6/9 cases), 0% for small lymphocytic B-cell lymphoma (0/3 cases), 100% for colon adenocarcinoma (2/2 cases), and 100% for hepatocellular carcinoma (2/2 cases). Conclusions MAGI-2 is overexpressed in most lymphomas and carcinomas from prostate, urinary bladder, ovary, pancreas, liver, and colon, but it is not detectable in small lymphocytic B-cell lymphoma by IHC for this study. Citation Format: Zhiming Liao. Immunohistochemical study of MAGI-2 expression in lymphomas and carcinomas from prostate, urinary bladder, ovary, pancreas, liver, and colon [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-245. doi:10.1158/1538-7445.AM2017-LB-245

Stevens-Johnson Syndrome after Treatment of Female Patient with Small Lymphocytic B-Cell Lymphoma, Autoimmune Hemolytic Anemia and Antiphospholipid Antibody Syndrome with Rituximab

Stevens-Johnson syndrome is a severe delayed type systemic allergic reaction which affects the skin and mucous membranes. In adults, Stevens-Johnson syndrome is usually caused by the administration of drugs or a malignant process. The paper presents a case of Stevens-Johnson syndrome after the treatment of a female patient with small lymphocytic B-cell lymphoma, autoimmune hemolytic anemia and antiphospholipid antibody syndrome with rituximab. A rare combination of Stevens-Johnson syndrome and small lymphocytic B-cell lymphoma of small lymphocytes, as well as the development of severe delayed type systemic allergic reaction to introduction of rituximab are of special interest. A detailed medical history and the clinical manifestations of the disease allowed to diagnose Stevens-Johnson syndrome at early stages and prescribe an adequate therapy. As a result of the treatment, the patient’s condition has improved considerably. Symptoms of general toxicity were arrested completely; there was a complete epithelization of erosive defects. Therefore, the presented clinical observation shows that timely diagnosis, complex drug therapy, and comprehensive care can cure the diseases as soon as possible and prevent complications.

Does categorisation of lymphoma subtypes according to the World Health Organization classification predict clinical outcome in cats?

Objectives The purpose of this study was to specify lymphoma subtypes according to the World Health Organization (WHO) classification in a group of cats and to investigate their potential prognostic value. Methods Records of cats from the University of Veterinary Medicine Vienna suffering from lymphoma were reviewed in this retrospective study. To diagnose various subtypes specified in the WHO classification, histopathological and immunohistochemical examinations, as well as clonality assays in some cases, were performed. Results Of the 30 cats included in this study and classified according to the WHO guidelines, peripheral T-cell lymphoma was the most prevalent lymphoma subtype (37% of cases; n = 11), followed by diffuse large B-cell (23%; n = 7), intestinal T-cell (10%; n = 3), T-cell-rich B-cell (10%; n = 3), large granular lymphocytic (7%; n = 2), anaplastic large T-cell (7%; n = 2), B-cell small lymphocytic (3%; n = 1) and T-cell angiotropic lymphoma (3%; n = 1). The median survival time (MST) was 5.4 months (range 6 days to 2.2 years), with two cats still alive after 1.7 and 2.0 years, respectively. Treating cats prior to chemotherapy with glucocorticoids did not worsen their prognosis. Adding to chemotherapy, radiotherapy or surgery did not improve the clinical outcome. We observed that patients with intestinal T-cell lymphoma lived significantly longer (MST 1.7 years) than those with a diffuse large B-cell (MST 4.5 months) or peripheral T-cell lymphoma (MST 6.1 months). Cats with T-cell-rich B-cell lymphoma survived significantly longer (MST 1.2 years) than those with a diffuse large B-cell lymphoma. Conclusions and relevance A detailed diagnosis of feline lymphoma can be obtained by allocating different subtypes according to the WHO classification. From the eight detected lymphoma subtypes, two, intestinal T-cell lymphoma and T-cell-rich B-cell lymphoma, showed promising survival times in cats.

B-cell small lymphocytic lymphoma associated with extremely high total IgE and cutaneous vasculitis

Extremely elevated polyclonal lgE of unknown etiology may indicate the presence of unsuspected B-cell lymphoma. In our patient, treatment of the lymphoma correlated with a reduction in serum lgE and complete resolution of the cutaneous vasculitis.

LEF1: a highly specific marker for the diagnosis of chronic lymphocytic B cell leukaemia/small lymphocytic B cell lymphoma

AimsChronic lymphocytic B cell leukaemia (CLL)/small lymphocytic B cell lymphoma (SLL) has proven to be not a uniform entity but to consist of various disease subtypes. CLL might also pose...

Immunohistochemical (IHC) Analysis of Non-Hodgkin's Lymphoma (NHL) Spectrum According to WHO/REAL Classification: A Single Centre Experience from Punjab, India.

The distribution of the major subtypes of non-Hodgkin's lymphoma (NHL) differs across geographic regions. This study, from the north Indian state of Punjab, has incorporated immunophenotypic findings while investigating the distribution of NHL subtypes based on World Health Organization (WHO)/ Revised European-American Classification of Lymphoid Neoplasms (REAL) system of classification. Over all seventy seven cases of lymphoma over a period of one year (between April 2012 and April 2013) were diagnosed in the Department of Pathology, Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar (Punjab). Of these 30 cases (39%) were of Hodgkin's Lymphoma (HL) and 47 cases (61%) were of Non Hodgkins lymphoma NHL. Of the total of cases of lympho-proliferative disorders, the diagnosis of NHL was done by light microscopy alone. All the cases diagnosed provisionally as NHL were taken up for immunophenotyping with Immunohistochemical (IHC) studies. There was 100 % concordance between the light microscopy and IHC studies. The individual NHL cases were classified according to the WHO/REAL classification according to the positive or relevant negative immonophenotypic expression and tabulated to ascertain the morphological spectrum of NHL in this part of the country. B-cell lymphomas formed 89.3%, whereas T-cell lymphomas formed 10.7% of the NHLs. Diffuse Large B-Cell Lymphoma (DLBCL) was the most common subtype (46.8% of all NHLs). B-cell small lymphocytic lymphoma, Mantle-Cell Lymphoma (MCL), marginal zone B-cell lymphomas (including MALT lymphomas), Diffuse, mixed small cleaved cell and large-cell type and Follicular centre-cell lymphomas amounted to 17%, 12.8%, 2.1%, 2.1% and 4.3%, respectively. Among the T-cell lymphomas, T-cell lymphoblastic lymphoma, anaplastic large-cell lymphomas of T/null-cell type, and Angioimmunoblastic T-cell lymphoma (AITL) accounted for 6.4%, 2.1%, and 2.1% of all NHL cases, respectively. The distribution of NHL subtypes in India shows disparity with those from the rest of the world. Follicular Lymphoma (FL) and MCL are less common in India compared to Europe and the USA. Peripheral T-cell lymphomas and T/NK-cell lymphomas of nasal and nasal types, which are common in many other Asian countries, are also less prevalent. T-cell lymphoblastic lymphoma and anaplastic large T/null cell lymphoma are more prevalent in India.

An unusual simultaneous occurence of gastric adenocarcinoma, leiomyoma and B-cell small lymphocytic lymphoma involving the perigastric lymph nodes and spleen

An unusual simultaneous occurence of gastric adenocarcinoma, leiomyoma and B-cell small lymphocytic lymphoma involving the perigastric lymph nodes and spleen

Mnogie nowotwory i transformacja Richtera u pacjenta z rozpoznaniem chłoniaka z małych limfocytów B – dylematy diagnostyczno-terapeutyczne

A clonal lymphocyte proliferation in patients with NHL interferes with the immune system, disturbing both humoral and cellular immunity. An antileukemic therapy additionally affects the immune system functioning. A higher than expected in general population incidence of infections and other malignancies is the consequence of impaired immunological surveillance. The fate of patients is also influenced by the possibility of low grade NHL transformation in more aggressive large B cell lymphoma, called the Richter's transformation.We present the case of patient with multiple malignancies small lymphocytic B-cell lymphoma (SLL), renal cell carcinoma (RCC), pulmonary adeno-carcinoma and recurrent laryngeal papillomas, that occurred in different stages of lymphoma diagnosis and treatment. He also developed SLL transformation in large B-cell lymphoma 7 years after the initial diagnosis.A clinical course, together with diagnostic and therapeutic difficulties we faced, are discussed in relation to the literature data.

Non-Hodgkin lymphoma of the cranial vault with retrobulbar metastasis mimicking a subacute subdural hematoma

Primary skeletal non-Hodgkin lymphoma is rare. The authors report a case of a small lymphocytic B-cell lymphoma of the skull occurring in a 53-year-old man who presented with right-hand apraxia. Initial computed tomography and magnetic resonance imaging revealed a hematoma-mimicking lesion in the left frontoparietal subdural area. A frontotemporoparietal craniectomy and biopsy procedure yielded a diagnosis of small lymphocytic B-cell lymphoma, with a metastatic nodule in the retrobulbar area. Three years after undergoing radiation therapy and surgery, the patient has shown neurological improvement without systemic dissemination of the malignancy. The lesion in this case was misdiagnosed as a subdural hematoma, and shows the importance of including lymphoma in the differential diagnosis of subdural mass lesions.

Ocular adnexal lymphoma subtyped according to the REAL classification: A 12-year experience from a single institution

18541 Background: The Revised European and American Lymphoma (REAL) classification (1994) provided a useful and practical tool to define lymphomas. The aim is to report our experience with this unusual malignancy diagnosed since the REAL classification was implemented. Methods: Retrospective review was performed on patients (pts) with ocular adnexal lymphoma between 1994 and 2006. Medical records, diagnostic imaging procedures, and pathology reports, including immunophenotyping studies, were reviewed. Histologic definition of lymphoma was based on the REAL Classification. Results: 10 pts were identified. All but one were females. Median age at diagnosis was 69 years (54–84). Primary sites included conjunctiva (5), orbital soft tissue (3), and eyelid (2). No lacrimal gland location was found. Ann Arbor stage at diagnosis was IE in most cases (7). One patient (pt) had stage IIE (conjunctival and maxillary sinus) and 2 pts had simultaneous bone marrow involvement (stage IV). 6 pts had marginal zone B-cell subtype, and the remaining 4 pts had small lymphocytic B-cell lymphoma. Radiation as single treatment modality was given to all 7 pts with stage IE, and all those achieved a complete remission (CR). CR was also achieved using chemotherapy with cyclophosphamide (C), vincristine (V), doxorubicin, prednisone (P), and rituximab followed by radiation in the pt with stage IIE. Of the 2 pts with stage IV, 1 achieved a CR with rituximab-based chemotherapy, and 1 never achieved a CR despite chemotherapy (chlorambucil, CVP). With a median follow-up of 23 months (9–70), the 9 pts that achieved a CR after initial treatment remain alive and disease-free. The only pt that did not achieve a CR lost follow-up at 18 months. Conclusions: In our patient population, radiation alone appears to be an effective treatment modality for stage IE. Achieving a CR seems to be a crucial factor for long-term control of the disease. No significant financial relationships to disclose.

Simultaneous occurrence of peripheral T-cell lymphoma unspecified and B-cell small lymphocytic lymphoma. Report of 2 cases

We report on 2 composite lymphomas occurring in elderly patients, morphologically characterized by the combination of peripheral T-cell lymphoma (PTCL) unspecified and B-cell small lymphocytic lymphoma. Immunohistochemistry provided objective confirmation of the coexistence of the 2 malignancies, as did molecular biology by revealing clonal T-cell receptor gamma and immunoglobulin heavy chain gene rearrangements. One of the patients had no history of indolent lymphoma either at the personal and family level, whereas the other showed a strong familial predisposition, his mother and sister having suffered from B-cell chronic lymphocytic leukemia. Epstein-Barr virus was detected in the PTCL component of 1 case, but was negative in the other. To the best of our knowledge, the simultaneous occurrence of PTCL unspecified and B-cell small lymphocytic lymphoma is an exceptional event; the possible pathogenetic correlations between the 2 neoplasms are discussed.

Synchronous Interdigitating Dendritic Cell Sarcoma and B-Cell Small Lymphocytic Lymphoma in a Lymph Node

A gradually enlarging axillary mass in a 79-year-old man was excised. The specimen was processed for light microscopy, immunohistochemical studies, and electron microscopy; gene rearrangement studies were also performed. A diagnosis of an interdigitating dendritic cell tumor of the lymph node and a B-cell small lymphocytic lymphoma occurring in the same anatomic location was made. We found that although rare cases of interdigitating dendritic cell tumor with an associated secondary malignancy have been described in the literature, to our knowledge, this is the first report of interdigitating dendritic cell tumor and synchronous neoplasm diagnosed at the same site. A possible relationship between the 2 disorders is also discussed.

Proteomic Analysis of Shed Membrane Microparticles from Malignant Lymphoid Cells: A New Tool for Membrane Proteins Studies.

Plasma membrane antigens are critical for the classification and diagnosis of chronic mature B-cell lymphocytic malignancies, illustrated by the extensive use of the Matutes score for CLL diagnosis. Nevertheless, new surface markers that could be detected using flow cytometry are still needed for the diagnostic and classification of a number of chronic lymphoid malignancies. In this aim, proteomic tools could be of great interest in order to detect such antigens, but analysis of plasma membrane proteins is limited by the difficulty of their purification and separation of membrane proteins with usual 2-dimensional electrophoresis have often been poor. For all these reasons, we proposed to take advantage of the physiological production of plasma membrane microvesicles in order to study plasma membrane proteins of malignant lymphoid cells. Indeed, when eukaryotic cells are submitted to stress conditions (including mitogenic activation or apoptosis), the constitutive asymmetry between the inner and outer leaflet of the plasma membrane is disrupted and fragments are released from the plasma membrane, constituting the so-called microparticles (MPs). Although MPs reflect at least in vitro the cell state, little is known on their protein composition. We describe here the first set of experiments aiming to characterize the MPs proteome. First, two ways of triggering MPs formation from a T-lymphocytic cell line were analyzed using a 1D-gel approach coupled with Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS). 390 proteins were identified in MPs among which 34% were localized to the plasma membrane. Replicate experiments from independent samples identified only very few nucleus or organelles proteins, but revealed a broad representation of plasma membrane proteins including seventeen hematopoietic clusters of differentiation and numerous signal transduction proteins. This approach was then successfully applied to circulating cells of a small-lymphocytic B-cell lymphoma. 414 proteins were identified in MPs, including 118 membrane proteins. In addition to various CD antigens, annexins, immunoglobulin chains and HLA antigens, proteins involved in the B-cell receptor signal transduction were recovered, including tyrosine kinases LYN, SYK, BTK, CSK, but also phospho-inositide 3-kinase (PI3K) phospholipase Cγ (PLCγ 2), hemopoietic cell kinase (HCK) and JAK1.Proteomic analysis of MPs may represent a new tool to study plasma membrane proteins, displaying the advantages of reproducibility, minimal organelle contamination and potentially applicable to most cell types. Extensive proteomic analysis of MPs may thus be a way to investigate differential expression of plasma membrane components and to identify new pathology markers that could help for diagnosis and classification.