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 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 Human memory B cells originate from three distinct germinal center-dependent and -independent maturation pathways

Blood ◽  
2011 ◽  
Vol 118 (8) ◽  
pp. 2150-2158 ◽  
Author(s):  
Magdalena A. Berkowska ◽  
Gertjan J. A. Driessen ◽  
Vasilis Bikos ◽  
Christina Grosserichter-Wagener ◽  
Kostas Stamatopoulos ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Somatic Hypermutation ◽  
Phenotypic Diversity ◽  
Human Memory ◽  
Memory B Cells ◽  
Memory B Cell ◽  
Effector Cells ◽  
B Cell Subsets

Abstract Multiple distinct memory B-cell subsets have been identified in humans, but it remains unclear how their phenotypic diversity corresponds to the type of responses from which they originate. Especially, the contribution of germinal center-independent responses in humans remains controversial. We defined 6 memory B-cell subsets based on their antigen-experienced phenotype and differential expression of CD27 and IgH isotypes. Molecular characterization of their replication history, Ig somatic hypermutation, and class-switch profiles demonstrated their origin from 3 different pathways. CD27−IgG+ and CD27+IgM+ B cells are derived from primary germinal center reactions, and CD27+IgA+ and CD27+IgG+ B cells are from consecutive germinal center responses (pathway 1). In contrast, natural effector and CD27−IgA+ memory B cells have limited proliferation and are also present in CD40L-deficient patients, reflecting a germinal center-independent origin. Natural effector cells at least in part originate from systemic responses in the splenic marginal zone (pathway 2). CD27−IgA+ cells share low replication history and dominant Igλ and IgA2 use with gut lamina propria IgA+ B cells, suggesting their common origin from local germinal center-independent responses (pathway 3). Our findings shed light on human germinal center-dependent and -independent B-cell memory formation and provide new opportunities to study these processes in immunologic diseases.

scholarly journals Polyreactivity and Somatic Hypermutation Analysis Reveals the Innate B Cell Origin of Human PF4/Heparin Reactive Antibodies

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 34-35
Author(s):  
Wen Zhu ◽  
Lu Zhou ◽  
Ting Zhao ◽  
Yongwei Zheng ◽  
Mei Yu ◽  
...  
Keyword(s):  
Immune Response ◽  
B Cells ◽  
B Cell ◽  
Peripheral Blood ◽  
Healthy Subjects ◽  
Somatic Hypermutation ◽  
Memory B Cells ◽  
Private Company ◽  
Platelet Factor ◽  
Polyreactive Antibodies

Heparin-induced thrombocytopenia (HIT) is a serious reaction to heparin treatment characterized by antibodies that recognize a complex formed between heparin and platelet factor 4 (PF4/H) and are capable of activating platelets and inducing a pro-thrombotic state. Although a high percentage of heparin-treated patients produce antibodies to PF4/H, only a subset of these antibodies are platelet-activating (pathogenic) and capable of causing HIT. We previously reported that we cloned B cells from six patients experiencing HIT and identified two types of PF4/H-binding antibodies: seven platelet-activating (PA) and 48 non-activating (NA). Comparison of the structural features in the PA, NA, and non PF4/H-binding (NB) clones showed that the length and the number of basic amino acid and tyrosine residue in the heavy chain complementarity determining region 3 (HCDR3) were significantly different, and was in the order of PA>NA>NB. Most significantly, the seven platelet-activating antibodies each have one of the two pathogenic motifs: RX1-2 R/KX1-2 R/H and YYYYY in an unusually long HCDR3 (≥ 20 residues). In the current study, we attempt to understand the origin of the B cells that produce the PA and NA antibodies and the nature of the immune response in HIT through analyzing somatic hypermutation and biological property of such antibodies. Longer HCDR3 and more basic Aas and Tyr residues in the HCDR3 are features of autoreactive and polyreactive antibodies. With this in mind, we tested PA and NA clones in a standard antinuclear antibody (ANA) assay and found that these clones were significantly more reactive than NB antibodies, and the plasma of HIT patients were significantly more reactive than normal plasma (Figure1). We then compared reactions of PA, NA and NB clones against a group of self and foreign antigens commonly used in polyreactivity assays: dsDNA, ssDNA, LPS, insulin, and keyhole limpet hemocyanin (KLH). About 90% of PA and NA clones were reactive to at least two antigens, this was true of only 20% of the NB clones, and the latter is consistent with the frequency of polyreactive clones in the IgG+ B cells (Figure2). Taken together, these data indicate that PA and NA antibodies are largely polyreactive. We then investigated the development of the PA and NA B cells through analyzing somatic hypermutation in the antibodies. Through analyzing the HCDR3 nucleotide insertion, trimming and VDJ segment usage, we found that longer HCDR3 typical of PF4/H-binding clones and the RKH and Y5 motifs identified in PA clones were the result of original recombination not somatic hypermutation. Consistently, the average number of nucleotide mutations in the VH genes of the binding clones was lower (PA and NA, 9.4 ± 9.5) compared to that of peripheral blood IgG+ memory B cells in healthy subjects (~18) (Figure3). Total mutation frequency in the VH and Vk CDRs of the PF4/H-binding PA and NA clones was comparable to that of the framework regions. This finding contrasts with findings made in peripheral blood IgG+ memory B cells of healthy subjects showing that the mutation frequencies are much higher in the CDRs than in the FRs of VH. Taken together, these findings suggest that affinity maturation plays a limited role in the evolution PF4/H-binding antibodies during the immune response that leads to HIT. In this study, we showed thay PF4/H-binding PA and NA IgGs are largely polyreactive antibodies and contain lower levels of mutations compared to IgG+ memory B cells. B1 and MZ B cells are innate B cells that are main producers of polyreactive natural antibodies and can respond to toll-like receptor signaling, quickly differentiate into antibody-secreting cells, and undergo IgG class switch extrafollicularly. Polyreactivity identified in the PF4/H-binding PA and NA IgGs supports the possibility that human B cells producing PF4/H-binding antibodies are innate B cells akin to MZ B cells shown to be a source of PF4/H antibodies in mice. A mutation rate lower than that of IgG+ memory cells in the PF4/H-binding IgGs is also consistent with an extrafollicular response typical of innate B cells. These observations would help to improve our understanding of the immunological responses and B cell origin in HIT patients. Disclosures Padmanabhan: Retham Technologies: Current equity holder in private company; Veralox Therapeutics: Membership on an entity's Board of Directors or advisory committees; Versiti Blood Research Institute: Patents & Royalties.

IGH Repertoire Analysis In Multiple Myeloma (MM): Lack of Intra-Disease Homology and Occasional Clustering with Sequences of Other B-Cell Neoplasms Sharing Identical Geographical Origin

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2951-2951
Author(s):  
Simone Ferrero ◽  
Daniela Capello ◽  
Mirija Svaldi ◽  
Daniela Drandi ◽  
Michela Boi ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
B Cells ◽  
B Cell ◽  
B Lymphocyte ◽  
Conflicts Of Interest ◽  
Residual Disease ◽  
Somatic Hypermutation ◽  
Cell Repertoire ◽  
Non Hodgkin Lymphoma ◽  
B Cell Subsets

Abstract Abstract 2951 Background: The identification of stereotyped immunoglobulin (IG) receptors has improved our knowledge on the pathogenesis of several B-cell malignancies, suggesting the role of antigen-driven stimulation in chronic lymphocitic leukemia (CLL), marginal-zone lymphoma (MZL) and mantle-cell lymphoma (MCL). Multiple myeloma (MM) is a terminally-differentiated neoplasm no longer expressing surface IG; however some reports suggest the existence of early B-lymphocyte precursors which could be susceptible to antigen-driven stimulation. IG heavy chain (IGH) repertoire has not been extensively investigated in MM, with the largest available reports containing less than 80 complete sequences. Aims: To address this issue we created a database of MM IGH sequences including our institutional records (mostly derived from minimal residual disease studies) and sequences available from the literature. We planned a two-step analysis: a) first we characterized the MM repertoire and performed intra-MM clustering analysis; b) then we compared our MM series to a large public database of IGH sequences from neoplastic and non-neoplastic B-cells in search of similarities between MM sequences and other normal or neoplastic IGH repertoires. Patients and methods: 131 MM IGH genes were amplified and sequenced at our Institutions and belonged to Italian patients, while 214 MM IGH sequences from non-Italian patients were derived from published databases (NCBI-EMBL-IMGT/LIGM-DB) for a total of 345 fully interpretable MM sequences (out of 396). 28590 IGH sequences from other malignant and non-malignant B-cells were retrieved from the same public databases, including approximately 4500 CLL/Non-Hodgkin lymphoma (NHL) sequences and comprising 500 sequences from Italian patients. All sequences were analyzed using the IMGT database and tools (Lefranc et al., Nucleic Acid Res. 2005; http://imgt.cines.fr/) to identify IGHV-D-J gene usage, to assess the somatic hypermutation (SHM) rate and to identify HCDR3. HCDR3 aminoacidic sequences were aligned together using the ClustalX 2.0 software (Larkin et al., Bioinformatics, 2007; http://www.clustal.org/). Subsets of stereotyped IGH receptors were defined according to Stamatopoulos et al. (Blood, 2007). Result: IGHV analysis in MM was almost in keeping with the normal B-cell repertoire, showing a less remarkably biased IGH usage compared to CLL, MCL and MZL (with seven genes accounting for 40% of cases, compared to respectively five, three and two genes). However, a modest but significant over-representation of IGHV1-69, 2–5, 2–70, 3–21, 3–30-3, 3–43, 5–51 and 6-1 genes and under-representation of the IGHV1-18, 1–8, 3–30, 3–53 and 4–34 was noticed. The rate of somatic hypermutation in MM followed a Gaussian distribution with a median value of 7.8%. Intra-MM search for HCDR3 similarities never met minimal requirements for stereotyped receptors. When MM sequences were compared to non-MM database, only a minority of MM sequences (2.6%, n=9) clustered with sequences from lymphoid tumors and normal B-cells (figure 1A). In particular two non-Italian MM sequences clustered with previously characterized, uncommon CLL subsets (n.37 and n.71 according to Murray et al., Blood 2008). Moreover, novel provisional clusters were observed including three MM-CLL subsets, one MM-NHL subset, and three MM-normal B-cell subsets. While the MM-normal B-cell clusters involved non-Italian patients, we unexpectedly noticed that the four MM-CLL/MM-NHL clusters were composed exclusively of Italian patients, as shown in figure 1B, although Italian subjects represented less than 12% of the entire CLL-NHL database. Conclusion: The analysis of the largest currently available database of MM IGH sequences indicates the following: 1) MM IGH repertoire is closer to physiological distribution than that of CLL, MCL and MZL; 2) MM specific clusters do not occur to a frequency detectable with currently available databases; 3) 98% of MM sequences are not related to other “highly-clustered” lymphoproliferative disorders; 4) Uncommon clustering phenomena may follow a geographical rather than a disease-related pattern. Disclosures: No relevant conflicts of interest to declare.

The immunoglobulin heavy-chain locus hs3b and hs4 3′ enhancers are dispensable for VDJ assembly and somatic hypermutation

Blood ◽  
2003 ◽  
Vol 102 (4) ◽  
pp. 1421-1427 ◽  
Author(s):  
Caroline Le Morvan ◽  
Eric Pinaud ◽  
Catherine Decourt ◽  
Armelle Cuvillier ◽  
Michel Cogné
Keyword(s):  
B Cells ◽  
B Cell ◽  
Heavy Chain ◽  
Somatic Hypermutation ◽  
Class Switch Recombination ◽  
Immunoglobulin Heavy Chain ◽  
Germinal Centers ◽  
Affinity Maturation ◽  
Class Switch ◽  
Endogenous Locus

Abstract The more distal enhancers of the immunoglobulin heavy-chain 3′ regulatory region, hs3b and hs4, were recently demonstrated as master control elements of germline transcription and class switch recombination to most immunoglobulin constant genes. In addition, they were shown to enhance the accumulation of somatic mutations on linked transgenes. Since somatic hypermutation and class switch recombination are tightly linked processes, their common dependency on the endogenous locus 3′ enhancers could be an attractive hypothesis. VDJ structure and somatic hypermutation were analyzed in B cells from mice carrying either a heterozygous or a homozygous deletion of these enhancers. We find that hs3b and hs4 are dispensable both for VDJ assembly and for the occurrence of mutations at a physiologic frequency in the endogenous locus. In addition, we show that cells functionally expressing the immunoglobulin M (IgM) class B-cell receptor encoded by an hs3b/hs4-deficient locus were fully able to enter germinal centers, undergo affinity maturation, and yield specific antibody responses in homozygous mutant mice, where IgG1 antibodies compensated for the defect in other IgG isotypes. By contrast, analysis of Peyer patches from heterozygous animals showed that peanut agglutinin (PNAhigh) B cells functionally expressing the hs3b/hs4-deficient allele were dramatically outclassed by B cells expressing the wild-type locus and normally switching to IgA. This study thus also highlights the role of germinal centers in the competition between B cells for affinity maturation and suggests that membrane IgA may promote recruitment in an activated B-cell compartment, or proliferation of activated B cells, more efficiently than IgM in Peyer patches.

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

EBV Can Induce Somatic Hypermutation in Naïve B Cells In Vitro but Ig Class Switching Requires T Cell Help.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2370-2370
Author(s):  
Sridhar Chaganti ◽  
Noelia Begue Pastor ◽  
Gouri Baldwin ◽  
Claire Shannon-Lowe ◽  
Regina Feederle ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Germ Line ◽  
Somatic Hypermutation ◽  
Memory B Cells ◽  
Class Switching ◽  
B Cell Subsets ◽  
T Cell Help

Abstract Following primary infection, Epstein-Barr virus (EBV) establishes life long persistence in the host IgD− CD27+ memory B cell compartment rather than the IgD+ CD27+ marginal zone (MZ)-like or the IgD+ CD27− naïve B cell compartments. One possible explanation for such exclusive persistence in memory B cells is that EBV preferentially infects memory B cells. Alternatively, the virus may infect all B cell subsets but then drive MZ and naïve B cells to acquire the Ig isotype-switched phenotype and hypermutated Ig genotype of memory cells. Here we ask whether there is any evidence for one or other hypothesis from in vitro experiments. B cells from healthy donor blood samples were FACS sorted on the basis of IgD/CD27 expression into naïve, MZ, and memory B cell subsets with purities of >99%, >97% and >98% respectively. Analysis of the IgVH sequence further confirmed purity of the FACS sorted B cell subsets. Accordingly, 102 of 105 IgVH sequences amplified from purified naïve B cells were germ-line where as the vast majority of sequences amplified from MZ and memory B cells were mutated. All three B cell subsets expressed equal amounts of CD21 (EBV receptor on B cells), bound similar amounts of virus, and transformed with equal efficiency to establish B lymphoblastoid cell lines (LCLs) in vitro. Naïve B cell transformants upregulated CD27 expression but retained the IgM+, IgD+ phenotype as determined by FACS analysis and RT-PCR; MZ-B derived LCLs likewise were IgM+, IgD+, CD27+; and memory-B derived LCLs were consistently CD27+, IgD− and expressed either IgG, IgA or in some cases IgM. Therefore, EBV infection per se did not induce class switching. However, both naïve and MZ-B derived LCLs could still be induced to switch to IgG in the presence of CD40 ligand and IL-4; signals that are normally provided by T cells in vivo. To assess if EBV infection might drive Ig hypermutation, we carried out IgVH sequence analysis on the naïve-B derived LCL clones. Interestingly, 42 of 114 clonal IgVH sequences amplified from naïve-B derived LCLs had 3 or more mutations and the patterns of mutation seen were consistent with that produced by somatic hypermutation (SHM). Furthermore, within some naïve-B cell derived LCL clones, there were both germ-line and mutated sequences all sharing the same VDJ rearrangement (CDR3 sequence), again implying sequence diversification following EBV transformation of a single naïve B cell. Some intraclonal variation of the already hypermutated IgVH sequence was also noted in memory and MZ-B derived LCLs further suggesting ongoing mutational activity. Consistent with this, activation-induced cytidine deaminase (AID) expression was upregulated in transformants as assessed by real time RT-PCR. Our in vitro data is therefore compatible with a model of EBV persistence where the virus infects all mature B cell subsets but then drives infected naïve B cells to acquire a memory genotype by inducing SHM. In addition, EBV infected naïve and MZ-B cells may undergo Ig class switching to acquire the IgD− CD27+ memory phenotype in the presence of T cell help in vivo. EBV’s ability to induce SHM may also contribute to the lymphomagenic potential of the virus in addition to its B cell transforming and growth promoting properties.

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.

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