The BRAF V600E Mutation in Hairy Cell Leukemia and Other Mature B-Cell Neoplasms

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 262-262 ◽  
Author(s):  
Luca Arcaini ◽  
Silvia Zibellini ◽  
Emanuela Boveri ◽  
Roberta Riboni ◽  
Sara Rattotti ◽  
...  
Keyword(s):  
Bone Marrow ◽  
B Cell ◽  
Cyclin D1 ◽  
Laboratory Data ◽  
Braf V600e Mutation ◽  
Lymphoid Cells ◽  
Braf V600e ◽  
Specific Pcr ◽  
Lymphoid Neoplasms ◽  
Wbc Count

Abstract Abstract 262 Hairy cell leukemia (HCL) is an indolent neoplasm of small mature B-lymphoid cells, which are found in peripheral blood and bone marrow (BM), and are characterized by hairy projections of their abundant cytoplasm. In clinical practice, HCL needs to be differentiated from similar indolent lymphoid neoplasms. In a study based on massively parallel sequencing of the whole exome of leukemic and matched normal cells from a HCL patient and subsequent targeted resequencing in additional patients, Tiacci et al (N Engl J Med. 2011 Jun 16;364:2305–15) have recently identified the BRAF V600E mutation as a genetic alteration associated with this disease. This somatic mutation was previously detected in diverse human cancers, with a particularly high frequency in melanoma (Nature. 2002 Jun 27;417:949–54; N Engl J Med. 2005 Nov 17;353:2135–47). In order to develop a reliable molecular diagnostic tool and verify its sensitivity and specificity in the diagnosis of HCL, we developed an allele-specific PCR for the BRAF V600E mutation, and searched for this molecular lesion in a series of 239 patients with mature B-cell lymphoid neoplasms. The study population included 62 patients with HCL, 91 with splenic marginal zone lymphoma (SMZL), 29 with Waldenström macroglobulinemia (WM), and 57 with B-cell chronic lymphoproliferative disorders (B-CLPD). Genomic DNA was extracted from bone marrow (BM) biopsies in 61 cases of HCL, from BM in 90 patients with diverse lymphoid neoplasms (33 SMZL, 29 WM, 28 B-CLPD), and from peripheral blood (PB) in the remaining 88 patients (1 HCL, 58 SMZL, 29 B-CLPD). The BRAF V600E mutation was detected in all patients with HCL (62/62) and in none of those with SMZL or WM. Two of the 57 patients with B-CLPD carried the mutation, and their clinical features are as follows. Case #1. This 41 year-old woman presented in November 2008 with asymptomatic lymphocytosis, without any evidence of lymphadenopathy, splenomegaly or hepatomegaly. Laboratory data showed: Hb 12.9 g/dL, WBC count 16 × 109/L (62% lymphoid cells), and PLT count 283 × 109/L. On BM biopsy, an interstitial lymphoid infiltrate (60% of the whole cellularity) composed by small, lymphocyte/centrocyte-like cells was found. By immunohistochemistry, neoplastic cells showed expression of CD20, CD79a and cyclin-D1, but were uniformly negative for CD5, CD10, CD23, CD25 and DBA44, and annexin A1. At flow cytometry analysis, they were CD20 and FMC7 positive and CD10, CD38, CD5, CD23, CD11c, CD25, DBA44 and CD103 negative. FISH for t(11;14), performed for cyclin D1 expression, was negative. Immunoglobulin rearrangement was IGHV3-48*02, IGHD7-27*01 IGHJ4*02. So far, lymphocytosis has remained stable and the patient is regularly followed without any need for treatment. Case #2. This 62 year-old male presented in 2006 with thrombocytopenia and splenomegaly, and was diagnosed with HCL was established in another hospital (no additional data are available). He was treated with cladribine with a partial response. In May 2008, we evaluated this patient in Pavia. The spleen was palpable 3 cm under the costal margin, and laboratory data showed: Hb 15.4 g/dL, WBC count 3.9 × 109/L, and PLT vount 95 × 109/L. BM biopsy showed a 20% lymphoid infiltrate with interstitial and sinusoidal pattern, composed by small to medium sized cells with evident nucleoli, resembling pro-lymphocytes. By immunohistochemistry, cells were positive for CD20 and negative for CD5, CD23, cyclin-D1, CD25, DBA44, and annexin A1. Flow cytometry demonstrated the expression of CD20, FMC7 and CD11c, partial expression (25%) of CD103, and negativity for CD5, CD10, CD38, CD23, DBA44, CD11c and CD25. This patient was asymptomatic and a watch-and wait-policy was adopted. These findings indicate that the allele-specific PCR we developed is able to detect the mutation in the bone marrow of all patients with HCL, and confirm that the BRAF V600E mutation is highly specific for HCL within mature B-cell neoplasms. Only 2/177 (1.1%) patients with lymphoid neoplasms other than HCL (2/57 or 3.5% of patients with B-CLPD) were positive for BRAF V600E. This is in agreement with a previous study that found BRAF mutations in 2.4% of patients with non-Hodgkin's lymphoma (Br J Cancer. 2003 Nov 17;89:1958–60). The detection of the BRAF V600E mutation in the clone (or, at least, in a subclone) of mature B-cell lymphoid neoplasms without typical HCL features might help to define their biology. Disclosures: No relevant conflicts of interest to declare.

scholarly journals The BRAF V600E mutation in hairy cell leukemia and other mature B-cell neoplasms

Blood ◽  
2012 ◽  
Vol 119 (1) ◽  
pp. 188-191 ◽  
Author(s):  
Luca Arcaini ◽  
Silvia Zibellini ◽  
Emanuela Boveri ◽  
Roberta Riboni ◽  
Sara Rattotti ◽  
...  
Keyword(s):  
Molecular Marker ◽  
B Cell ◽  
Hairy Cell Leukemia ◽  
Lymphoproliferative Disorders ◽  
Braf V600e Mutation ◽  
Braf V600e ◽  
Splenic Marginal Zone Lymphoma ◽  
Hairy Cell ◽  
Cell Leukemia ◽  
Specific Pcr

Abstract The somatically acquired V600E mutation of the BRAF gene has been recently described as a molecular marker of hairy cell leukemia (HCL). We developed an allele-specific PCR for this mutation and studied 62 patients with HCL, 1 with HCL variant, 91 with splenic marginal zone lymphoma, 29 with Waldenström macroglobulinemia, and 57 with B-cell chronic lymphoproliferative disorders. The BRAF V600E mutation was detected in all HCL cases and in only 2 of the remaining 178 patients. These 2 subjects had B-cell chronic lymphoproliferative disorders that did not fulfill the diagnostic criteria for HCL. Despite the positive PCR finding, the mutation could not be detected by Sanger sequencing in these 2 cases, suggesting that it was associated with a small subclone. We conclude that the BRAF V600E mutation is present in all patients with HCL and that, in combination with clinical and morphologic features, represents a reliable molecular marker for this condition.

scholarly journals Two Atypical Cases of Classical Hairy Cell Leukaemia and Hairy Cell Leukaemia Variant: A Case Study

2020 ◽  
Vol 1 ◽  
Author(s):  
S.A.C.D. Ranatunga ◽  
B.L.T. Balasuriya ◽  
C.C. Kariyawasan
Keyword(s):  
Bone Marrow ◽  
B Cell ◽  
Clinical Findings ◽  
Braf V600e Mutation ◽  
Hairy Cell Leukaemia ◽  
Braf V600e ◽  
Full Blood Count ◽  
Cell Leukaemia ◽  
Hairy Cell ◽  
Cervical Lymph Nodes

Introduction: Classical Hairy Cell Leukaemia (cHCL) and Hairy Cell Leukaemia variant (HCL-v) are both rare and slow-growing mature B cell neoplasms. According to flowcytometry data, they fall into the group classified as CD5- CD10- B cell lymphoproliferative disorders. Methods: Two cases with features atypical to two neoplasms at the time of diagnosis were studied. Results: Case 1 was a 15 year old male with right cervical lymph nodes (1x1 cm) in the posterior triangle, a few ecchymotic patches on the arm and a massive splenomegaly. C-reactive protein (CRP) level was 53 mg/dL. Erythrocyte Sedimentation Rate (ESR) was 98 mm/1 st hour. Full Blood Count (FBC) revealed typical features of pancytopenia with monocytopenia. The liver and renal profiles were normal. Morphology of bone marrow was suggestive of cHCL. Flowcytometry and BRAF V600E mutation was positive confirming the diagnosis of cHCL. Case 2 was a 55 year old male presenting with moderate splenomegaly and absolute lymphocytosis. The FBC revealed leukocytosis which is commonly seen with monocytopenia. Blood pictures revealed many hairy cells with moderately basophilic cytoplasm and visible nucleoli suggesting HCL-v. Flowcytometry findings and negative BRAF V600E mutation confirmed HCL-v. Conclusions: Clinical findings, blood images, morphology of bone marrow, flowcytometric findings and positive BRAF V600E mutation confirmed the diagnosis of cHCL in case 1 (15 year old boy) making it as a very rare case. The morphological findings on blood, the presence of characteristic CD markers on flowcytometry and negativity of BRAF V600E confirmed the case 2 as HCL-v, despite having CD10 positivity and monocytopenia.Keywords: Flowcytometric immunophenotyping, Hairy cell leukaemia, Hairy cell leukaemia variant

scholarly journals Both variant and IGHV4-34–expressing hairy cell leukemia lack the BRAF V600E mutation

Blood ◽  
2012 ◽  
Vol 119 (14) ◽  
pp. 3330-3332 ◽  
Author(s):  
Liqiang Xi ◽  
Evgeny Arons ◽  
Winnifred Navarro ◽  
Katherine R. Calvo ◽  
Maryalice Stetler-Stevenson ◽  
...  
Keyword(s):  
B Cell ◽  
Hairy Cell Leukemia ◽  
Poor Prognosis ◽  
Braf V600e Mutation ◽  
Braf V600e ◽  
Hairy Cell ◽  
Cell Leukemia ◽  
Wild Type ◽  
Ighv Gene ◽  
Gene Usage

Abstract Recently, the BRAF V600E mutation was reported in all cases of hairy cell leukemia (HCL) but not in other peripheral B-cell neoplasms. We wished to confirm these results and assess BRAF status in well-characterized cases of HCL associated with poor prognosis, including the immunophenotypically defined HCL variant (HCLv) and HCL expressing the IGHV4-34 immunoglobulin rearrangement. Fifty-three classic HCL (HCLc) and 16 HCLv cases were analyzed for BRAF, including 5 HCLc and 8 HCLv expressing IGHV4-34. BRAF was mutated in 42 (79%) HCLc, but wild-type in 11 (21%) HCLc and 16 (100%) HCLv. All 13 IGHV4-34+ HCLs were wild-type. IGHV gene usage in the 11 HCLc BRAF wild-type cases included 5 IGHV4-34, 5 other, and 1 unknown. Our results suggest that HCLv and IGHV4-34+ HCLs have a different pathogenesis than HCLc and that a significant minority of other HCLc are also wild-type for BRAF V600.

scholarly journals Mice lacking c-fos have normal hematopoietic stem cells but exhibit altered B-cell differentiation due to an impaired bone marrow environment.

1994 ◽  
Vol 14 (1) ◽  
pp. 382-390 ◽  
Author(s):  
S Okada ◽  
Z Q Wang ◽  
A E Grigoriadis ◽  
E F Wagner ◽  
T von Rüden
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
B Cell ◽  
Cell Development ◽  
B Cell Development ◽  
Lymphoid Cells ◽  
Mutant Mice ◽  
Hematopoietic Stem ◽  
Developmental Potential

Mice lacking c-fos develop severe osteopetrosis with deficiencies in bone remodeling and exhibit extramedullary hematopoiesis, thymic atrophy, and altered B-cell development. In this study, we have used these mice to characterize in detail the developmental potential of hematopoietic stem cells lacking c-fos and to analyze how the lymphoid differentiation is altered. In c-fos -/- mice, B-cell numbers are reduced in the spleen, lymph nodes, and the peripheral blood as a result of a marked reduction (> 90%) in the number of clonogenic B-cell precursors. In contrast, the number and lineage distribution of myeloid progenitor cells are not affected. The thymic defects observed in a large number of these mice correlate with their health status, suggesting that this may be an indirect effect of the c-fos mutation. In vitro differentiation and bone marrow reconstitution experiments demonstrated that hematopoietic stem cells lacking c-fos can give rise to all mature myeloid as well as lymphoid cells, suggesting that the observed B lymphopenia in the mutant mice is due to an altered environment. Transplantation of wild-type bone marrow cells into newborn mutant mice resulted in the establishment of a bone marrow space and subsequent correction of the B-cell defect. These results demonstrate that hematopoietic stem cells lacking Fos have full developmental potential and that the observed defect in B-cell development is most likely due to the impaired bone marrow environment as a consequence of osteopetrosis.

scholarly journals A Quantitative Allele-Specific PCR Test for the BRAF V600E Mutation Using a Single Heterozygous Control Plasmid for Quantitation

2013 ◽  
Vol 15 (2) ◽  
pp. 248-254 ◽  
Author(s):  
Philippe Szankasi ◽  
N. Scott Reading ◽  
Cecily P. Vaughn ◽  
Josef T. Prchal ◽  
David W. Bahler ◽  
...  
Keyword(s):  
Braf V600e Mutation ◽  
Braf V600e ◽  
Specific Pcr ◽  
Control Plasmid ◽  
Allele Specific ◽  
Allele Specific Pcr ◽  
Pcr Test

scholarly journals Promising Real World Survival Data in Adult-Onset Langerhans Cell Histiocytosis: An Australasian Lymphoma Alliance 20 Year Retrospective Study

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2570-2570
Author(s):  
Georgia Mills ◽  
John Moore ◽  
Edward Cliff ◽  
Chun Yew Fong ◽  
Sarah Mangalasseril ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Research Funding ◽  
Progressive Disease ◽  
Treatment Strategies ◽  
Braf V600e Mutation ◽  
Braf V600e ◽  
Adult Onset ◽  
Cns Involvement ◽  
Mutation Status

Abstract Background: Langerhans Cell Histiocytosis (LCH) is a rare inflammatory neoplasm originating from bone marrow-derived CD207+/CD1+ clonal dendritic cells, with cells expressing BRAF V600E in around 50% of cases. Although more common in the paediatric setting, LCH is rare in adults, with an incidence of 1 to 2 cases per million. This combination of disease heterogeneity and infrequency means that data on treatment strategies and outcomes is limited, and a consensus on management is lacking. Data has historically been extrapolated from the larger paediatric cohort, with emerging phase II data on the efficacy and safety of upfront methotrexate and cytosine arabinoside (AraC) in adult LCH. Other agents used include cladribine (CdA), hydroxyurea, vinblastine, and prednisolone-based regimens, and more recently MEK/BRAF inhibitors, but none of these have been trialled prospectively. LCH can be an aggressive disease with a poor prognosis. Methods : We included patients aged ≥18 years diagnosed with LCH on histopathology between January 1, 2000 and August 1, 2021 from ten sites across Australia and New Zealand. Variables included demographic data, system and organ involvement, central nervous system (CNS) involvement, bone marrow involvement and BRAF V600E mutation status. Outcomes measured included overall survival (OS), progression-free survival (PFS) and total lines of therapy. Response to therapy was modified from the Scoring System of the HS LCH III trial: Complete response (CR) was defined by resolution of all signs of disease activity, including neuroendocrine dysfunction, skin and radiological lesions; and a partial response (PR) was defined as patients with "active disease better" and those with "mixed response". Stable or worsening symptoms/radiology were classified as progressive disease (PD). Patients who were alive or lost to follow-up were censored on the date of last follow-up. Results : We identified 46 patients with a median age at diagnosis of 39 years (range 18-81) (Table 1). The sex ratio was 1. 41% of patients had MS-LCH at diagnosis, of which 24% had high risk organ (liver, bone marrow, or spleen) involvement. 37% had multifocal bone disease. 28% of patients had CNS involvement at diagnosis. BRAF V600E mutation status was assessed in only 43% of cases, with a mutation frequency of 40%. The median number of lines of therapy was 1.7 (range 0-9). Three patients (7%) underwent lung transplantation for isolated pulmonary LCH. 31% percent of patients were treated with chemotherapy upfront, with the majority receiving AraC (43%,) and the remainder receiving vinblastine, prednisolone and 6-mercaptopurine (6-MP) (21%), vinblastine/prednisolone (21%), CdA (14%) or methotrexate and 6-MP (2%). Of note, 67% (n=4) of patients who were treated with upfront AraC and 100% (n=2) of patients treated with upfront CdA had a CR, while those patients treated with upfront vincristine-based regimes had, at best, a PR (50%, n=3) or PD (50%). Of the 46 patients, with a median follow up of 34.6 months (range 0.63-250.2), there were 7 deaths (15%) with 6/7 due to progressive disease, and the remaining death due to complications of lung transplantation. Median OS was not reached (Figure 1), while OS at 5 years was 85%. Median PFS was 9 years (range 0.05-21) (Figure 2), with a non-significant trend towards reduced PFS in patients with MS-LCH (5 years) compared to SS-LCH (9 years) (Figure 3). There was also a trend towards reduced OS in patients who received AraC as systemic therapy versus other forms of systemic therapy. Conclusion: We report the largest multicentre Australasian cohort of patients diagnosed with adult-onset LCH. OS and PFS were longer than previously reported in the literature. There remains significant heterogeneity in diagnostic and treatment strategies. There was a trend towards improved response rate to upfront AraC or CdA when compared to the vinblastine-based regimens, and further prospective research with these agents is required in this setting. Progress in this disease is challenging due its rarity, highlighting the need for standardisation of diagnostic and treatment strategies as well as a national and/or international registry. Figure 1 Figure 1. Disclosures Fong: Amgen: Research Funding; AbbVie, Amgen, Novartis, Pfizer, Astellas: Honoraria; Amgen, BMS: Speakers Bureau. Ku: Antegene: Consultancy; Roche: Consultancy; Genor Biopharma: Consultancy. Cunningham: Principia Biopharma: Research Funding; Rigel: Research Funding; Janssen: Research Funding; Novartis: Research Funding; AbbVie: Research Funding; Amgen: Research Funding; Astex: Research Funding; Celgene: Research Funding. Hamad: Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

scholarly journals The Pathologic Spectrum of Bone Marrow Involvement by Double- and Triple-hit Lymphomas

2021 ◽  
Vol 156 (Supplement_1) ◽  
pp. S96-S97
Author(s):  
H Iqbal ◽  
A Harrington ◽  
S H Kroft
Keyword(s):  
Bone Marrow ◽  
B Cell ◽  
Bone Marrow Involvement ◽  
Laboratory Data ◽  
Large Cell ◽  
Proliferation Index ◽  
High Grade ◽  
B Cell Lymphomas ◽  
Lymphoma Cells ◽  
Pathologic Features

Abstract Introduction/Objective B-cell lymphomas with MYC and BCL2 and/or BCL6 rearrangements (double- and triple-hit lymphomas, DHL/THL) are a distinct entity due to shared biology and aggressive behavior, exhibiting poor outcomes with standard therapies. While pathologic features of DHL/THLs in primary sites have been well described, little information is available regarding the clinicopathologic features of bone marrow involvement by this entity. Methods/Case Report Files were searched from 2010-2020 for all DHL/THLs. Since mid-2016, all aggressive B-cell lymphomas were reflexed to DHL/THL FISH testing. Prior to that, criteria for performing FISH varied. Clinical and laboratory data were obtained through chart review. Both BM and primary diagnostic specimens were reviewed when possible. Results (if a Case Study enter NA) There were 46 DHL/THL cases with initial staging BM evaluations, of which 13 (28%) were positive for DHL/THL; 11 were available for review (5F:6M; 28-95 years). All patients with positive BMs were stage 3 or 4 irrespective of the BM findings. Lymphoma cytology in positive BMs was blastoid in 6, large cell in 2, and high grade, NOS in 3. The cytology in primary tissues was not significantly associated with the rate of marrow involvement. PB smears were available for 9/11 BM(+) cases; of these, 6 (66.7%) had circulating lymphoma cells in the blood, ranging from rare to greater than 40% lymphoma cells (median, 4%). Lymphoma cells with cytoplasmic vacuoles were present in 5 cases (45%). No BM infiltrates had a starry-sky appearance. Infiltration patterns included diffuse (3), diffuse and interstitial (3), and interstitial (3). One exhibited only rare, scattered lymphoma cells in the aspirate and core biopsy, and another with large cell morphology showed random focal (nodular) and focally paratrabecular infiltration. The proliferation index in the marrow infiltrates ranged from 50% to >90% (median, 65%). Flow cytometry was positive in 9 of 10 cases; the single negative study was from an outside institution Conclusion Our study demonstrates 28% of DHL/THLs show BM involvement at diagnosis. Notably, the peripheral blood was involved in 2/3 of cases with marrow infiltration (13% of total cases), ranging from rare circulating cells to frank leukemic involvement. Cytologically, the marrow infiltrates were predominantly blastoid or high grade NOS. Marrow infiltrates generally displayed leukemic rather than lymphomatous patterns of involvement.

scholarly journals Expression of interleukin-4 receptors on early human B-lineage cells

Blood ◽  
1991 ◽  
Vol 78 (3) ◽  
pp. 703-710 ◽  
Author(s):  
CL Law ◽  
RJ Armitage ◽  
JG Villablanca ◽  
TW LeBien
Keyword(s):  
Bone Marrow ◽  
B Cell ◽  
Constitutive Expression ◽  
Lymphoid Cells ◽  
Interleukin 4 ◽  
B Cell Differentiation ◽  
Fluorescent Intensity ◽  
B Cell Growth Factor ◽  
B Lineage

Interleukin-4 (IL-4) regulates multiple stages of the antigen-dependent phase of B-cell development. However, its precise role in regulating B lymphopoiesis in bone marrow is not as well defined. We examined whether surface IgM- normal and leukemic human B-cell precursors (BCP) expressed IL-4 receptors using biotinylated IL-4. Constitutive expression of IL-4 receptors was detected on both normal and leukemic BCP. A higher percentage of normal BCP (82% +/- 15%) expressed IL-4 receptors compared with leukemic BCP (44% +/- 8%). Using mean fluorescent intensity as an indicator of receptor level on the IL-4 receptor positive cells, normal (91 +/- 41) and leukemic (44 +/- 37) BCP expressed comparable numbers of receptors. IL-4 induced the expression of CD23 on 30% of the leukemic BCP cases examined. IL-4 induced CD23 on surface IgM+ fetal bone marrow lymphoid cells but not on the surface IgM- normal BCP, despite the presence of detectable receptors on the surface IgM- cells. IL-4 did not stimulate proliferation of normal BCP, nor could it enhance the effect of recombinant IL-7 or low molecular weight B-cell growth factor. However, IL-4 increased the expression of surface IgM and surface Ig kappa on in vitro differentiated pre-B cells. Our collective results identify no role for IL-4 in the proliferation of normal or leukemic BCP, but identify a role in the enhancement of surface Ig expression during pre- B to B-cell differentiation.

scholarly journals Culture of human fetal B-cell precursors on bone marrow stroma maintains highly proliferative CD20dim cells

Blood ◽  
1993 ◽  
Vol 81 (5) ◽  
pp. 1170-1178 ◽  
Author(s):  
I Moreau ◽  
V Duvert ◽  
J Banchereau ◽  
S Saeland
Keyword(s):  
Bone Marrow ◽  
B Cell ◽  
Optimal Growth ◽  
Lymphoid Cells ◽  
Interleukin 7 ◽  
Cd20 Expression ◽  
Cell Layers ◽  
Marrow Stroma ◽  
B Cell Precursors ◽  
Dose Dependent

Growth of human B-cell precursors (BCP) was achieved by plating fetal CD10+ surface-mu (s mu)- cells in liquid medium onto bone marrow- derived fibroblastic stromal cell layers deprived of hematopoietic cells. Proliferation of the fetal BCP was strongly potentiated by the addition of interleukin-7 (IL-7) to the cultures. Cultures included both a stroma-adherent and -nonadherent fraction of lymphoid cells, allowing us to expand the number of input BCP to 13-fold. In the presence of exogenous IL-7, proliferation was dose-dependent relative to the number of stromal cells, demonstrating that soluble IL-7 does not act alone to promote optimal growth. We further showed that the lymphoid cells recovered remain CD10+ sIg- BCP and that most cells expressed the maturation-associated CD20 antigen when IL-7 was added to the cultures. Whereas both freshly isolated CD20- and CD20bright BCP proliferated in the presence of stroma, we observed that high- proliferative capacity CD20dim cells were maintained in the cultures. Finally, CD20dim sorted cells were shown to subsequently acquire high levels of CD20 expression in culture, thus demonstrating a partial maturation sequence. The present culture system thus represents a useful model for studying the regulatory signals in early human B lymphopoiesis.

scholarly journals Ligation of CD38 suppresses human B lymphopoiesis.

1995 ◽  
Vol 181 (3) ◽  
pp. 1101-1110 ◽  
Author(s):  
M Kumagai ◽  
E Coustan-Smith ◽  
D J Murray ◽  
O Silvennoinen ◽  
K G Murti ◽  
...  
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
B Cell ◽  
Lymphoblastic Leukemia ◽  
Lymphoid Cells ◽  
Leukemic Cells ◽  
B Lymphopoiesis ◽  
Normal Peripheral Blood ◽  
Enzymatic Function ◽  
Lymphoid Progenitors

CD38 is a transmembrane glycoprotein expressed in many cell types, including lymphoid progenitors and activated lymphocytes. High levels of CD38 expression on immature lymphoid cells suggest its role in the regulation of cell growth and differentiation, but there is no evidence demonstrating a functional activity of CD38 on these cells. We used stroma-supported cultures of B cell progenitors and anti-CD38 monoclonal antibodies (T16 and IB4) to study CD38 function. In cultures of normal bone marrow CD19+ cells (n = 5), addition of anti-CD38 markedly reduced the number of cells recovered after 7 d. Cell loss was greatest among CD19+ sIg- B cell progenitors (mean cell recovery +/- SD = 7.2 +/- 11.7% of recovery in control cultures) and extended to CD19+CD34+ B cells (the most immature subset; 7.6 +/- 2.2%). In contrast, CD38 ligation did not substantially affect cell numbers in cultures of normal peripheral blood or tonsillar B cells. In stroma-supported cultures of 22 B-lineage acute lymphoblastic leukemia cases, anti-CD38 suppressed recovery of CD19+ sIg- leukemic cells. CD38 ligation also suppressed the growth of immature lymphoid cell lines cultured on stroma and, in some cases, in the presence of stroma-derived cytokines (interleukin [IL] 7, IL-3, and/or stem cell factor), but did not inhibit growth in stroma- or cytokine-free cultures. DNA content and DNA fragmentation studies showed that CD38 ligation of stroma-supported cells resulted in both inhibition of DNA synthesis and induction of apoptosis. It is known that CD38 catalyzes nicotinamide adenine dinucleotide (NAD+) hydrolysis into cyclic ADP-ribose (cADPR) and ADPR. However, no changes in NAD+ hydrolysis or cADPR and ADPR production after CD38 ligation were found by high-performance liquid chromatography; addition of NAD+, ADPR, or cADPR to cultures of lymphoid progenitors did not offset the inhibitory effects of anti-CD38. Thus, anti-CD38 does not suppress B lymphopoiesis by altering the enzymatic function of the molecule. In conclusion, these data show that CD38 ligation inhibits the growth of immature B lymphoid cells in the bone marrow microenvironment, and suggest that CD38 interaction with a putative ligand represents a novel regulatory mechanism of B lymphopoiesis.

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