scholarly journals Characteristics of CD11c+CD5+ chronic B-cell leukemias and the identification of novel peripheral blood B-cell subsets with chronic lymphoid leukemia immunophenotypes [see comments]

Blood ◽  
1990 ◽  
Vol 76 (1) ◽  
pp. 123-130 ◽  
Author(s):  
SB Wormsley ◽  
SM Baird ◽  
N Gadol ◽  
KR Rai ◽  
RE Sobol
Keyword(s):  
B Cells ◽  
B Cell ◽  
Peripheral Blood ◽  
Small Lymphocyte ◽  
Lymphoid Leukemia ◽  
Color Flow ◽  
Prolymphocytic Leukemia ◽  
Normal Peripheral Blood ◽  
Chronic Lymphoid Leukemia ◽  
B Cell Subsets

Previous studies have indicated that chronic lymphocytic leukemias (CLL) are characterized by the coexpression of CD5 and B-cell antigens, while hairy cell leukemias (HCL) typically express CD11c+CD5- B-cell immunophenotypes. In this report we describe the features of B-cell leukemias with CD11c+CD5+ immunophenotypes and the identification of novel circulating B-cell subsets defined by the expression of CD20, CD5, and CD11c antigens. Morphologic evaluation of 14CD11c+CD5+ B-cell leukemias showed that they generally had larger cellular diameters (14 to 21 microns) and lower nuclear:cytoplasm ratios than typical small lymphocyte CLL. These cases did not exhibit the well-defined nucleoli characteristic of prolymphocytic leukemia (PLL). The presenting clinical features of CD11c+CD5+ B-cell leukemias were most consistent with CLL or PLL, and none of the evaluated cases had pancytopenia, splenomegaly, and cytoplasmic villi characteristic of HCL. Examination of normal peripheral blood (n = 6) by three-color flow cytometry identified four novel B-cell subsets with the following immunophenotypes (mean percent of total CD20+ B cells +/- SE): CD20+CD5+CD11c+ (8.0 +/- 1.6); CD20+CD5-CD11c+ (12.0 +/- 2.0); CD20+CD5+CD11c- (35.0 +/- 4.9); and CD20+CD5-CD11c- (44.0 +/- 5.0). Our findings suggest that CD11c+CD5+ B-cell leukemias with atypical morphologic features represent forms of CLL or PLL rather than HCL. In addition, we have identified novel subsets of circulating B cells defined by patterns of CD20, CD5, and CD11c expression that correspond to the immunophenotypes of chronic B-cell leukemias.

scholarly journals Characteristics of CD11c+CD5+ chronic B-cell leukemias and the identification of novel peripheral blood B-cell subsets with chronic lymphoid leukemia immunophenotypes [see comments]

Blood ◽  
1990 ◽  
Vol 76 (1) ◽  
pp. 123-130 ◽  
Author(s):  
SB Wormsley ◽  
SM Baird ◽  
N Gadol ◽  
KR Rai ◽  
RE Sobol
Keyword(s):  
B Cells ◽  
B Cell ◽  
Peripheral Blood ◽  
Small Lymphocyte ◽  
Lymphoid Leukemia ◽  
Color Flow ◽  
Prolymphocytic Leukemia ◽  
Normal Peripheral Blood ◽  
Chronic Lymphoid Leukemia ◽  
B Cell Subsets

Abstract Previous studies have indicated that chronic lymphocytic leukemias (CLL) are characterized by the coexpression of CD5 and B-cell antigens, while hairy cell leukemias (HCL) typically express CD11c+CD5- B-cell immunophenotypes. In this report we describe the features of B-cell leukemias with CD11c+CD5+ immunophenotypes and the identification of novel circulating B-cell subsets defined by the expression of CD20, CD5, and CD11c antigens. Morphologic evaluation of 14CD11c+CD5+ B-cell leukemias showed that they generally had larger cellular diameters (14 to 21 microns) and lower nuclear:cytoplasm ratios than typical small lymphocyte CLL. These cases did not exhibit the well-defined nucleoli characteristic of prolymphocytic leukemia (PLL). The presenting clinical features of CD11c+CD5+ B-cell leukemias were most consistent with CLL or PLL, and none of the evaluated cases had pancytopenia, splenomegaly, and cytoplasmic villi characteristic of HCL. Examination of normal peripheral blood (n = 6) by three-color flow cytometry identified four novel B-cell subsets with the following immunophenotypes (mean percent of total CD20+ B cells +/- SE): CD20+CD5+CD11c+ (8.0 +/- 1.6); CD20+CD5-CD11c+ (12.0 +/- 2.0); CD20+CD5+CD11c- (35.0 +/- 4.9); and CD20+CD5-CD11c- (44.0 +/- 5.0). Our findings suggest that CD11c+CD5+ B-cell leukemias with atypical morphologic features represent forms of CLL or PLL rather than HCL. In addition, we have identified novel subsets of circulating B cells defined by patterns of CD20, CD5, and CD11c expression that correspond to the immunophenotypes of chronic B-cell leukemias.

scholarly journals In VitroMeasles Virus Infection of Human Lymphocyte Subsets Demonstrates High Susceptibility and Permissiveness of both Naive and Memory B Cells

2018 ◽  
Vol 92 (8) ◽  
pp. e00131-18 ◽  
Author(s):  
Brigitta M. Laksono ◽  
Christina Grosserichter-Wagener ◽  
Rory D. de Vries ◽  
Simone A. G. Langeveld ◽  
Maarten D. Brem ◽  
...  
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Immune Suppression ◽  
Peripheral Blood ◽  
Measles Virus ◽  
Memory B Cells ◽  
T And B Cells ◽  
B Cell Subsets

ABSTRACTMeasles is characterized by a transient immune suppression, leading to an increased risk of opportunistic infections. Measles virus (MV) infection of immune cells is mediated by the cellular receptor CD150, expressed by subsets of lymphocytes, dendritic cells, macrophages, and thymocytes. Previous studies showed that human and nonhuman primate memory T cells express higher levels of CD150 than naive cells and are more susceptible to MV infection. However, limited information is available about the CD150 expression and relative susceptibility to MV infection of B-cell subsets. In this study, we assessed the susceptibility and permissiveness of naive and memory T- and B-cell subsets from human peripheral blood or tonsils toin vitroMV infection. Our study demonstrates that naive and memory B cells express CD150, but at lower frequencies than memory T cells. Nevertheless, both naive and memory B cells proved to be highly permissive to MV infection. Furthermore, we assessed the susceptibility and permissiveness of various functionally distinct T and B cells, such as helper T (TH) cell subsets and IgG- and IgA-positive memory B cells, in peripheral blood and tonsils. We demonstrated that TH1TH17 cells and plasma and germinal center B cells were the subsets most susceptible and permissive to MV infection. Our study suggests that both naive and memory B cells, along with several other antigen-experienced lymphocytes, are important target cells of MV infection. Depletion of these cells potentially contributes to the pathogenesis of measles immune suppression.IMPORTANCEMeasles is associated with immune suppression and is often complicated by bacterial pneumonia, otitis media, or gastroenteritis. Measles virus infects antigen-presenting cells and T and B cells, and depletion of these cells may contribute to lymphopenia and immune suppression. Measles has been associated with follicular exhaustion in lymphoid tissues in humans and nonhuman primates, emphasizing the importance of MV infection of B cellsin vivo. However, information on the relative susceptibility of B-cell subsets is scarce. Here, we compared the susceptibility and permissiveness toin vitroMV infection of human naive and memory T- and B-cell subsets isolated from peripheral blood or tonsils. Our results demonstrate that both naive and memory B cells are more permissive to MV infection than T cells. The highest infection levels were detected in plasma cells and germinal center B cells, suggesting that infection and depletion of these populations contribute to reduced host resistance.

scholarly journals IgM+IgD+CD27+ B cells are markedly reduced in IRAK-4–, MyD88-, and TIRAP- but not UNC-93B–deficient patients

Blood ◽  
2012 ◽  
Vol 120 (25) ◽  
pp. 4992-5001 ◽  
Author(s):  
Sandra Weller ◽  
Mélanie Bonnet ◽  
Héloïse Delagreverie ◽  
Laura Israel ◽  
Maya Chrabieh ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Signaling Pathways ◽  
Size Distribution ◽  
Heavy Chain ◽  
Peripheral Blood ◽  
Somatic Hypermutation ◽  
Key Factors ◽  
Tlr Signaling ◽  
B Cell Subsets

Abstract We studied the distribution of peripheral B-cell subsets in patients deficient for key factors of the TLR-signaling pathways (MyD88, TIRAP/MAL, IL-1 receptor–associated kinase 4 [IRAK-4], TLR3, UNC-93B, TRIF). All TLRs, except TLR3, which signals through the TRIF adaptor, require MyD88 and IRAK-4 to mediate their function. TLR4 and the TLR2 heterodimers (with TLR1, TLR6, and possibly TLR10) require in addition the adaptor TIRAP, whereas UNC-93B is needed for the proper localization of intracellular TLR3, TLR7, TLR8, and TLR9. We found that IgM+IgD+CD27+ but not switched B cells were strongly reduced in MyD88-, IRAK-4-, and TIRAP-deficient patients. This defect did not appear to be compensated with age. However, somatic hypermutation of Ig genes and heavy-chain CDR3 size distribution of IgM+IgD+CD27+ B cells were not affected in these patients. In contrast, the numbers of IgM+IgD+CD27+ B cells were normal in the absence of TLR3, TRIF, and UNC-93B, suggesting that UNC-93B–dependent TLRs, and notably TLR9, are dispensable for the presence of this subset in peripheral blood. Interestingly, TLR10 was found to be expressed at greater levels in IgM+IgD+CD27+ compared with switched B cells in healthy patients. Hence, we propose a role for TIRAP-dependent TLRs, possibly TLR10 in particular, in the development and/or maintenance of IgM+IgD+CD27+ B cells in humans.

scholarly journals Immunoglobulin secretory function of B cells from untreated patients with chronic lymphocytic leukemia and hypogammaglobulinemia: role of T cells

Blood ◽  
1983 ◽  
Vol 62 (4) ◽  
pp. 767-774 ◽  
Author(s):  
LA Fernandez ◽  
JM MacSween ◽  
GR Langley
Keyword(s):  
T Cells ◽  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
B Lymphocytes ◽  
Peripheral Blood ◽  
Cell Function ◽  
Lymphocytic Leukemia ◽  
Suppressor Activity ◽  
Normal Peripheral Blood

Abstract The mechanism of the hypogammaglobulinemia in patients with chronic lymphocytic leukemia (CLL) was studied by determining the generation of specific immunoglobulin-secreting cells in response to mitogen and antigen stimulation in culture. Normal peripheral blood B lymphocytes from 18 normal subjects cocultured with equal numbers of autologous T cells generated cells secreting 2,542 +/- 695 IgG, 2,153 +/- 615 IgA, and 2,918 +/- 945 IgM. Normal B lymphocytes cocultured with normal allogeneic T cells generated similar numbers. However, B lymphocytes from patients with chronic lymphocytic leukemia cocultured with T cells from the same patient generated only 0.5% as many cells secreting IgG and 11% and 23% as many secreting IgA and IgM, respectively. The reason for this markedly defective generation of immunoglobulin-secreting cells was investigated by evaluating T-helper, T-suppressor, and B-cell function using B cells from tonsil and T and B cells from peripheral blood of normal and leukemic individuals. T cells from patients with chronic lymphocytic leukemia provided somewhat greater help than did normal T cells to normal peripheral blood B cells and normal help to tonsil B cells, whether stimulated with mitogen or antigen. T cells from patients with chronic lymphocytic leukemia did not demonstrate increased suppressor function compared to normals with B cells from normal peripheral blood. The hypogammaglobulinemia in these patients therefore was associated with a markedly defective generation of immunoglobulin secreting cells, and as there was normal or increased T- cell helper activity without excessive suppressor activity, it seems likely that this was due to an intrinsic B-cell defect.

scholarly journals OP0024 DECREASED LEVELS OF T FOLLICULAR HELPER (CD4+CXCR5+) CELLS AND CD27+CD38+ AND CD27+CD38- B CELLS IN ANKYLOSING SPONDYLITIS PATIENTS CORRELATE WITH MARKER OF INFLAMMATION

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 13.2-14
Author(s):  
H. Forsblad-D’elia ◽  
U. Hellman ◽  
A. Kumar ◽  
K. Lejon
Keyword(s):  
Ankylosing Spondylitis ◽  
B Cells ◽  
B Cell ◽  
Peripheral Blood ◽  
Mononuclear Cells ◽  
Female Patients ◽  
Tfh Cells ◽  
Follicular Helper ◽  
B Cell Subsets

Background:The role of different lymphocyte subsets in ankylosing spondylitis (AS) is still to be elucidated. It has previously been reported contradictory data concerning the levels of T Follicular Helper (TFH) cells and differentiated B cells in peripheral blood of AS patients. In addition, the connection to disease related parameters is still to be fully revealed.Objectives:The purpose of this study was to investigate the level of CD4+TFH cells and CD27+CD38+/CD38- B cells in patients with AS from northern Sweden and to compare the levels with age and sex-matched controls. We also studied associations between these cell subsets and disease related factors.Methods:Peripheral blood mononuclear cells (PBMSc) from a cohort of 50 patients with AS from Region Västerbotten (mean age 52±9.1 years, 33 (66 %) men, 50 (100 %) HLAB27 positive) and 50 pair wise matched blood donor controls (mean age 54±8.8 years, 33 (66 %) men) were stained with a combination of antibodies allowing for the detection of CD27, CD38, CD19, CD3, CD4 and CXCR5 markers and analyzed by flow cytometry. In addition, the patient with AS were examined with spinal x-ray for radiographic alterations assessed with mSASSS. CRP and ESR were measured and physical function and disease activity were registered with BASMI and BASFI respectively ASDAS-CRP and BASDAI.Results:When comparing AS patients and controls pair wise, we observed on average a 50% reduction of TFH (CD3+CD4+CXCR5+) cells among CD45+ lymphocytes in PBMCs from patients (p=0,000008). Furthermore, a 20-30% reduction among memory/plasma cells (CD19+CD27+CD38+ and CD19+CD27+CD38-) among CD45+ lymphocytes in PBMCs from patients (p=0,002 and p=0,007 respectively). For female patients a correlation between TFH and ESR (Rs=-0,551 p=0,022) was observed. Moreover, negative correlations between the two B cell subsets (CD19+CD27+CD38+ and CD19+CD27+CD38-) and ESR were observed for female patients (Rs =–0,476 p=0,053 and Rs =–0,522 p=0,032 respectively).Conclusion:TFH cells was reduced in AS patients and this reduction correlated with a reduction in differentiated (CD27+CD38+ and CD27+CD38-) B cells. In addition, the inflammation marker ESR was negatively correlated with TFH as well as with the differentiated B cell subsets in female patients. Our observations indicates a role of the humoral immune response in AS.Disclosure of Interests:None declared

scholarly journals Presence of intragraft B cells during acute renal allograft rejection is accompanied by changes in peripheral blood B cell subsets

2019 ◽  
Vol 196 (3) ◽  
pp. 403-414 ◽  
Author(s):  
S. Heidt ◽  
M. Vergunst ◽  
J. D. H. Anholts ◽  
G. M. J. S. Swings ◽  
E. M. J. Gielis ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Peripheral Blood ◽  
Allograft Rejection ◽  
Renal Allograft ◽  
Renal Allograft Rejection ◽  
Acute Renal Allograft Rejection ◽  
B Cell Subsets

scholarly journals THU0040 PROTEINASE 3-REACTIVE B CELL RECONSTITUTION AFTER TREATMENT WITH RITUXIMAB FOR ANCA-ASSOCIATED VASCULITIS

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 233.1-233
Author(s):  
A. Berti ◽  
S. Hillion ◽  
A. Hummel ◽  
E. Carmona ◽  
T. Peikert ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
B Cells ◽  
B Cell ◽  
Peripheral Blood ◽  
Proteinase 3 ◽  
Research Support ◽  
Color Flow ◽  
Anca Associated Vasculitis ◽  
Cell Repopulation

Background:Proteinase 3 (PR3)-reactive B cells are present in PR3-ANCA-associated vasculitis (AAV) at levels higher than healthy controls.Objectives:To evaluate the dynamics of the PR3-reactive B cell repopulation in patients with PR3-AAV after treatment with rituximab, and to analyze possible associations between these immunological changes and long-lasting remissions.Methods:We analyzed all available frozen peripheral blood mononuclear cells (n=148) from 23 randomly-selected PR3-AAV patients who participated in the RAVE trial and achieved complete remission (BVAS=0, prednisone=0) after treatment with rituximab.We measured PR3-reactive B cells and the relative subsets by a multi-color flow cytometry panel including CD19, IgD, CD27, CD38, CD24, and a biotinylated PR3 revealed by fluorescent streptavidin. The clinical data of the trial were correlated with flow-cytometry data.Results:10/23 (43%) patients relapsed during the follow up, 8/10 relapses were severe. At baseline, clinical features, PR3-ANCA levels, % of total PR3-reactive B cells and PR3-reactive B cell subsets were similar between relapsers and non-relapsers. All patients were followed until the end of the trial, for a mean of 44 months (25-75%IQR 31-54), without difference in follow-up time between relapsers and non-relapsers (p=0.98).The majority of patients had B cell repopulation at 12 (range 12-24) months after rituximab. At the time of B cell repopulation, transitional (CD19+CD24+CD38+) and naïve (CD19+CD27+IgD-) B cells were higher compared to baseline, while total plasmablasts (PB) were unchanged, and mature B cells significantly decreased in both relapsers and non relapsers. PR3-reactive B cells reappeared in all the patients, and the % of PR3-reactive of B cells were higher at the B cell repopulation visit compared to baseline (5.82% vs 4.25%, p<0.05), while total B cells were lower (66/μL vs 151/μL, p<0.01), regardless of future relapse.Within PR3-reactive B cells, only the % of PB (CD19+CD27+CD38+PR3+) were higher in relapsers vs. non-relapsers (median [25-75%IQR]; 1.95% [1.315-3.845] vs 0.84% [0.05-1.66], p=0.022) and severe relapsers vs non-severe relapsers (2.165% [1.66-4.315] vs 0.84% [0.1-1.74], p=0.015). Time-to-relapse and time-to severe-relapse were significantly shorter in patients with circulating PR3-PB higher than the median value of the cohort (1.6%) during B cell reconstitution (Figure 1A-B).Conclusion:In PR3-AAV, during B cell reconstitution after rituximab, the total fraction of PR3-B cells increases, due to the expansion of the transitional and naïve B cell compartments. Circulating PR3-PB within PR3-B cells are enriched in the peripheral blood of relapsing and severely relapsing patients compared to non-relapsing patients. Higher levels of PR3-PB after rituximab during B cell reappearance significantly increased the risk of subsequent relapse and severe relapse.References:[1]Cornec D, Berti A, Hummel A, et al. J Autoimmun. 2017Disclosure of Interests:Alvise Berti: None declared, Sophie Hillion: None declared, Amber Hummel: None declared, Eva Carmona: None declared, Tobias Peikert: None declared, Carol Langford: None declared, Peter A. Merkel: None declared, Paul Monach: None declared, Philip Seo: None declared, Robert Spiera Grant/research support from: Roche-Genetech, GSK, Boehringer Ingelheim, Chemocentryx, Corbus, Forbius, Sanofi, Inflarx, Consultant of: Roche-Genetech, GSK, CSL Behring, Sanofi, Janssen, Chemocentryx, Forbius, Mistubishi Tanabe, E. William St. Clair: None declared, Fernando Fervenza: None declared, Kristina Harris: None declared, John H. Stone Grant/research support from: Roche, Consultant of: Roche, Jacques-Olivier Pers: None declared, Ulrich Specks: None declared, Divi Cornec: None declared

scholarly journals A cytotoxic monoclonal antibody detecting a novel B cell membrane antigen expressed predominantly on cells bearing surface membrane immunoglobulin

Blood ◽  
1984 ◽  
Vol 63 (2) ◽  
pp. 319-325 ◽  
Author(s):  
J Jephthah ◽  
PI Terasaki ◽  
F Hofman ◽  
W Wolde-Marian ◽  
JB Peter ◽  
...  
Keyword(s):  
B Cells ◽  
Peripheral Blood ◽  
Surface Membrane ◽  
Myelogenous Leukemia ◽  
Malignant Cells ◽  
Prolymphocytic Leukemia ◽  
Normal Peripheral Blood ◽  
B Lymphoma ◽  
Membrane Immunoglobulin ◽  
Cytotoxicity Studies

Abstract A new human B lymphocyte membrane antigen, CB2, has been detected by a mouse monoclonal IgM antibody. CB2 appears to be predominantly expressed on normal and malignant cells expressing surface membrane immunoglobulin (SmIg). By indirect immunofluorescence, the number of CB2-positive cells in normal peripheral blood correlated well with the number of SmIg-positive cells. Cytotoxicity studies on isolated cell populations showed that CB2 was present on normal B cells isolated from the spleens of 52 donors and on peripheral blood B cells from 8 donors. Monocytes, T cells, granulocytes, platelets, and red cells were CB2 negative. Only malignant cells expressing SmIg were positive. These included B-CLL, B lymphoma, prolymphocytic leukemia, and B lymphoma cell lines Daudi, Raji, and Conception. SmIg-negative leukemia cells, such as common acute lymphoblastic leukemia, acute and chronic myelogenous leukemia, and T cell leukemias, were negative. Blocking studies with human immunoglobulin suggests that the CB2 antigen is not directed against immunoglobulin determinants. Immunoperoxidase studies on normal lymph node sections show that CB2-positive cells are predominantly present in the mantle region of the follicle, whereas B1- positive cells are mainly in the germinal center.

BAFF-R Receptor Also Functions in the Nucleus of Normal and Neoplastic Human B Lymphocytes.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2368-2368
Author(s):  
Lingchen Fu ◽  
Yen-Chiu Lin-Lee ◽  
Archito Tamayo ◽  
Linda Yoshimura ◽  
Richard J. Ford
Keyword(s):  
Plasma Membrane ◽  
B Cells ◽  
B Cell ◽  
Cell Survival ◽  
B Lymphocytes ◽  
Cell Nucleus ◽  
Peripheral Blood ◽  
Target Genes ◽  
B Lymphocyte ◽  
Normal Peripheral Blood

Abstract B-lymphocyte stimulator (BLyS) is a relatively newly described tumor necrosis factor (TNF) superfamily cytokine involved in cell survival and proliferation in normal and neoplastic B cells, particularly in the aggressive B cell non-Hodgkin’s lymphomas (NHL-B). BLyS binds to three receptors: BAFF-R (or BR3), BCMA and TACI. However, recent studies have shown that BLyS regulates B cell survival and proliferation predominately through BAFF-R. Mice with mutant BAFF-R show significant decrease in the peripheral blood B-lymphocyte compartment, similar to the phenotype of BLyS knockout mice. BLyS/BAFF-R signaling functions through activation of the critical transcription factor NF-kB pathways, especially the NF-kB2 pathway, which mainly involves the p52/ rel-B complex. Our previous studies have shown that BLyS is constitutively expressed in aggressive NHL-B cells leading to increased survival and proliferation of the malignant B cells. In this study, we found by western blotting and confocal microscopy that BAFF-R, the major B cell associated cell membrane receptor for BLyS, was also present in the B cell nucleus, in addition to its location in plasma membrane and cytoplasm in both normal peripheral blood B lymphocytes and NHL-B cells. Nuclear presence can be increased by anti-IgM and soluble CD154 treatment in normal peripheral blood B lymphocytes, and is constitutively expressed in aggressive NHL-B. Inhibition of BLyS expression by specific BLyS siRNA decreases nuclear BAFF-R level and survival in LBCL cells. Immunostaining experiments show that in the cytoplasm of normal and neoplastic B cells, BAFF-R interacts with the improtin a and b which are members of the classic karypherin pathway. A candidate nuclear localization sequence (NLS) was also identified in the BAFF-R protein sequence, and mutation of this putative NLS can block BAFF-R entering nucleus, which is consistent with our hypothesis that BAFF-R undergoes nuclear translocation. To further investigate the functional role of BAFF-R in nucleus, we performed confocal immunostaining analysis and co-immunoprecipitation, that shows that BAFF-R co-localizes with some NF-kB family members such as c-rel in the B cell nucleus. We also found that nuclear BAFF-R/c-rel complex can bind to the NF-kB binding site on the promoters of NF-kB target genes such as BLyS, CD154, Bcl-xL and Bfl-1 /A1 by chromatin immnoprecipitation (ChIP) assay. Luciferase reporter assays show that BAFF-R has transactivation activity on these NF-kB target genes. Furthermore, NLS mutant BAFF-R decreases NF-kB target gene promoter activity, compared to wild type BAFF-R, and NHL-B cell proliferation. These findings indicates that in addition to activating NF-kB pathways at the plasma membrane, BAFF-R may also promote survival and proliferation of both normal and NHL-B cell in the nucleus by directly regulating transcriptional activity of key NF-kB target genes and may functions as a transcriptional co- factor with NF-kB.

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