B cell receptor (BCR) is a key molecule involved in B cell specific recognition and the binding of antigens to produce adaptive humoral immune response. Gene rearrangement and high frequency mutation during B cell differentiation are the main mechanisms of BCR diversification. The enormous diversity and unique molecular structure of BCR determine the diversity and specificity of antigen recognition, shaping complex B cell repertoire with extensive collections of antigen specificities. Therefore, BCR antigen-specific information is vital to understanding the adaptive immune characteristics of different diseases. Our ability to connect BCR repertoire and antigen specificity has been enhanced with the development of B cell related research technologies, such as single cell sorting techniques, high-throughput sequencing (HTS), linking B cell receptor to antigen specificity through sequencing (LIBRA-seq). It could help researchers to better understand humoral immune responses, identify disease pathogenesis, monitor disease progression, design vaccines, and develop therapeutic antibodies and drugs. We summarizes recent studies on antigen-specific BCR of infections, vaccinations, autoimmune diseases and cancer. By analyzing autoantibody sequences of SLE as a case, the identification of autoantigens has become potentially possible due to this characterization.
Receptors, Antigen, B-Cell/metabolism* ; B-Lymphocytes/metabolism* ; Lymphocyte Activation ; High-Throughput Nucleotide Sequencing/methods*

<b>OBJECTIVEb>To investigate the expression of miR-9 in B lymphocytes, B cell lymphoma and classical Hodgkin's lymphoma (cHL) cell lines and its significance.

<b>METHODSb>CD19(+) B lymphocytes were sorted from normal lymph node by magnetic beads. Total cellular micro-RNA was extracted from cHL cell line L428, B cell lymphoma cell lines Ly1 and Ly10 (diffuse large B cell lymphoma), Raji cells (Burkitt's lymphoma) and CD19(+) B lymphocytes, respectively. These micro-RNAs were separately transformed into cDNA by reverse transcription. The expression levels of miR-9 were measured by fluorescence quantitative PCR. In situ hybridization was used to detect the expression of miR-9 in cell lines.

<b>RESULTSb>The expression of miR-9 was high in L428 cells (104.44 ± 1.61), and low in cell lines of B cell lymphoma (Ly1: 2.17 ± 0.38; Ly10: 1 ± 0.015; Raji: 2.65 ± 0.89), and extremely low in CD19(+) B lymphocytes (0.0026 ± 0.00040). Compared with that in the other cell lines, the expression of miR-9 in L428 cells was statistically significant (P < 0.05). miR-9 localized in the cytoplasm diffusely and strongly in L428, but scattered and slightly with some prominent distribution around the nuclear membranes in Ly1 and Ly10, and only weakly in Raji.

<b>CONCLUSIONSb>miR-9 highly expressed in cHL cell line and might be a molecular marker for diagnosis and treatment of cHL.

B-Lymphocytes ; metabolism ; Cell Line, Tumor ; Cell Lineage ; Hodgkin Disease ; metabolism ; pathology ; Humans ; Lymphoma, B-Cell ; metabolism ; pathology ; MicroRNAs ; metabolism

The humoral immune response of B cells is the key to the protection of specific immunity, and immune aging reshapes its production and function. The decreased B cell immune function is an indicator of immune senescence. The impaired humoral immune function mediated by antibody secreted by B cells leads to a decline in the response of elderly individuals to the vaccine. These people are therefore more susceptible to infection and deterioration, and have a higher incidence of tumors and metabolic diseases. Activation-induced cytidine deaminase (AID) is an enzyme that triggers immunoglobulin class conversion recombination (CSR) and somatic high frequency mutation (SHM). It decreases during immune senescence and is considered to be a biomarker of decreased B cell function in aging mice and humans. Understanding the inherent defects of B-cell immune senescence and the regulation mechanism of AID in the aging process can provide new research ideas for the susceptibility, prevention and treatment of diseases in the elderly.
Animals ; Humans ; Mice ; Aging/metabolism* ; B-Lymphocytes/metabolism* ; Cytidine Deaminase/metabolism* ; Somatic Hypermutation, Immunoglobulin

OBJECTIVE: To study cellular immune function of palatine tonsil B lymph cell. METHOD: The phenotype of palatine tonsil cells (PTC) and that of peripheral blood mononuclear cell (PBMC) were compared using fluorescence staining and flow cytometry (FCM) analysis, then immunomagnetic beads were used to separate CD3- cell in PTC and PBMC. The proliferation function of CD3- lymph cell of PTC and PBMC was tested after stimulated by CD20mAb. RESULT: FCM analysis founding that 71.2% PTC express CD20 with higher mean fluorescence intensity, MFI, compared to the 15.5% in PBMC. There's no significant difference between the proliferation of PTC and PBMC B lymph cell. CONCLUSION CD20 expression is different in PTC and PBMC, but corresponding function is still unknown.
Adult ; Antigens, CD20 ; metabolism ; B-Lymphocytes ; cytology ; immunology ; metabolism ; Flow Cytometry ; Humans ; Palatine Tonsil ; cytology ; immunology

OBJECTIVE: To detect receptor activator of nuclear factor kappa B ligand (RANKL) expressed on B10 cells in rheumatoid arthritis (RA) and to evaluate the correlation between RANKL-producing B10 cells in RA and clinical features and laboratory parameters, trying to reveal the possible role of B10 cells in the pathogenesis of RA and the potential mechanism of impaired immunosuppressive capacities. METHODS: 25 RA patients and 20 healthy volunteers were enrolled. These RA patients did not received treatment with glucocorticoids, disease-modifying anti-rheumatic drug and biologics during the recent half of a year. The levels of RANKL-producing B10 cells were measured by flow cytometry (FCM) and polymerase chain reaction (PCR). The correlation between the frequencies of RANKL-producing B10 cells in RA and clinical data, laboratory parameters were analyzed. The role of tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β) in inducing RANKL expression in B10 cells was evaluated by in vitro stimulation assay. Independent samples t test, Pearson and Spearman correlation were used for statistical analysis. RESULTS: B10 cells were capable of producing RANKL at a low level in health controls. The frequencies of RANKL-producing B10 cells were markedly higher in RA patients than in health controls (3.65%±1.59% vs. 2.25%±0.68%, P<0.01). The frequencies of these cells correlated positively with RA tender joint counts, swollen joint counts and disease activity score in 28 joints (DAS28) (r=0.479, P=0.035; r=0.519, P=0.008; r=0.526, P=0.019). However, no correlation was found between these cells and RA patient age, disease duration, or the levels of erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid factor (RF) and anti-citrullinated peptide antibody (ACPA). After in vitro stimulation by TNF-α, but not IL-1β, B10 cells isolated from healthy donors demonstrated fundamentally upregulated expression of RANKL. CONCLUSION Our studies showed the frequencies of RANKL-producing B10 cells were markedly higher in RA patients, and their frequencies were positively correlated with RA tender joint counts, swollen joint counts and DAS28. These findings suggested that B10 cells might be involved in RA bone destruction.
Antirheumatic Agents ; Arthritis, Rheumatoid/metabolism* ; Autoantibodies/metabolism* ; B-Lymphocytes, Regulatory/metabolism* ; Humans ; RANK Ligand/metabolism* ; Rheumatoid Factor

CD4(+)CD25(+)CD127(dim/-) regulatory T cells (Tregs) have been implicated in suppressing T cell immune responses to hepatitis B virus (HBV), but the inhibition mechanism has not being clear yet. This study investigated the effects of soluble FGL2 (sFGL2) secreted by Tregs on immune suppression in chronic HBV-infected patients. We verified that sFGL2 protein and mRNA were highly expressed in Tregs. The separated Tregs by using magnetic beads from peripheral blood mononuclear cells (PBMCs) in 20 patients with chronic hepatitis B were co-cultured with PBMCs at a ratio of 1:3 with anti-CD3 stimulating antibody or FGL2 blocking antibody. The proliferation index of CD8(+)T cells after blocking FGL2 was higher than that in blank group (3.58±0.18 vs. 3.28±0.17, P=0.034) in 18 of 20 samples, and lower than that in CD3 stimulation group (3.82±0.19, P=0.026) in 16 of 20 samples. The IFN-γ secreted in the mixed culture in the absence of Tregs was higher than that in the culture in the presence of Tregs, but it could be abolished by FGL2 blocking antibody. These results suggest that sFGL2 protein secreted by Tregs suppresses the proliferation and function of CD8(+) T cells in chronic hepatitis B.
CD8-Positive T-Lymphocytes ; immunology ; metabolism ; Cells, Cultured ; Fibrinogen ; immunology ; metabolism ; Hepatitis B, Chronic ; immunology ; metabolism ; Humans ; T-Lymphocytes, Regulatory ; immunology ; metabolism

<b>BACKGROUNDb>Previous studies indicate that CD43 plays a role in regulating the adhesion of lymphocytes, cell mutation and activation, however, little is known about its effect on systemic lupus erythematosus (SLE). This study was designed to explore the clinical significance of CD43 in SLE patients.

<b>METHODSb>We used microarray and real-time PCR to detect the mRNA and protein expression of magnetic bead sorted T cells and B cells from peripheral blood mononuclear cells (PBMCs) of SLE patients, and analyzed the relationship between CD43 and the clinical indexes.

<b>RESULTSb>Both microarray and real-time PCR results showed that CD43 mRNA was significantly decreased in PBMCs of SLE patients compared with healthy controls (P < 0.001). There were no significant differences between lupus nephritis and non-lupus nephritis patients, and neuropsychiatric and non-neuropsychiatric patients. CD43 mRNA expression was significantly reduced in T cells but not in B-cells in SLE patients compared to healthy controls (P < 0.01). Compared with healthy controls, the percentage of CD43(+) cells in the PBMCs of SLE was significantly decreased (P = 0.004), and the CD43 fluorescence intensity in CD3(+)/CD43(+) cells and CD19(+)/CD43(+) cells was also significantly weaker than in healthy controls (P = 0.039 and 0.003). There was no significant difference in the percentage of CD3(+)/CD43(+) cells, CD19(+)/CD43(+) cells between the two groups. The CD43 fluorescence intensity in CD3(+)/CD43(+) cells was inversely correlated with the levels of IgG and IgM (r = -0.8 and -0.6).

<b>CONCLUSIONSb>Compared to healthy controls, both CD43 mRNA and protein expressions were reduced in T cells from patients with SLE, and were inversely correlated with IgG.

B-Lymphocytes ; immunology ; metabolism ; Humans ; Leukocytes, Mononuclear ; Leukosialin ; genetics ; metabolism ; Lupus Erythematosus, Systemic ; immunology ; metabolism ; Oligonucleotide Array Sequence Analysis ; Real-Time Polymerase Chain Reaction ; T-Lymphocytes ; immunology ; metabolism

OBJECTIVE: To study the correlation of the expression alteration of Tim-3 with the T cell and B cell dysfunction in peripheral blood of multiple myeloma (MM) patients. METHODS: 30 patients diagnosed as MM from October 2016 to October 2018 were selected and enrolled in MM group, and 30 healthy persons whose sex and age was matched with the MM patients were selected and enrolled in healthy control group (HC). The blood samples from MM patients and HC were collected, and the peripheral blood mononuclear cells (PBMNC) were separated by density gradient centrifugation, then the serum was kept for further study. The ratios of CD3CD4Tim-3T cells, CD3CD8Tim-3T cells and the CD19+CD20-CD38+B cells were analysed by flow cytometry (FCM)，and the concentration of T cell-related cytokines IFN-γ, TNF-αand B cell-related antibodies IgA, IgM and IgG were measured by ELISA. At the same time, the differences of the ratios of CCD3CD4Tim-3T, CD3CD8Tim-3T cells and plasmablast and the concentration of IFN-γ, TNF-α, IgA, IgM and IgG between the MM patient and HC were estimated, and the correlation of the ratio of CD3CD4Tim-3T, CD3CD8Tim-3T cells with the ratio of plasmablast and the concentration of IFN-γ, TNF-α, IgA, IgM and IgG in MM patients were analyzed. RESULTS: The ratio of CD3CD4Tim-3T, CD3CD8Tim-3T cells increased in MM patients, while the ratio of CD19+CD20- CD38+B cells and the concentration of IFN-γ, TNF-α, IgA, IgM and IgG decreased in MM patients. And there was a negative correlation of the ratio of CD3CD4Tim-3T cells with CD19+CD20-CD38+B cells and the concentration of IFN-γ, IgA, IgM and IgG in MM patients, while the ratio of CD3CD8Tim-3T cells just negatively correlated with the concentration of TNF-α. CONCLUSION Expression of Tim-3 on CD4 and CD8 cells elevates in the peripheral blood of MM patients, which also correlates with the function suppression of T and B cells.
B-Lymphocytes ; CD8-Positive T-Lymphocytes ; Hepatitis A Virus Cellular Receptor 2 ; metabolism ; Humans ; Leukocytes, Mononuclear ; Multiple Myeloma

<b>OBJECTIVEb>To study the association between hepatitis B virus (HBV) mutants and the pathogenesis of severe hepatitis B by full-length HBV genome.

<b>METHODSb>Serum samples from 10 severe hepatitis B patients were collected in our hospital. Serum HBV DNAs were extracted using DNA mini Kit, and amplified by LA Taq DNA polymerase to yield full-length HBV DNA. PCR products were isolated and cloned into vector pUCm-T, then transfected into DH-5 alpha cells. Positive clones were selected and checked by digestion, and full-length HBV DNAs were sequenced.

<b>RESULTSb>4 cases were cloned into vector pUCm-T successfully and completed the full-length sequencing. Among them, 3 cases had a G to A mutation at nucleotide 1896 in pre-C region and 1 had a double mutation of T1762-A1764 in the core promoter region. Some amino acid changes occurred within the known CTL, B or T cell epitopes of the PrS2 and C regions.

<b>CONCLUSIONSb>This method could serve to study the relationship between HBV genome and the pathogenesis of severe hepatitis B.

Adult ; B-Lymphocytes ; metabolism ; Cloning, Molecular ; Epitopes ; genetics ; Genome, Viral ; genetics ; Hepatitis B ; etiology ; virology ; Hepatitis B Surface Antigens ; genetics ; Hepatitis B virus ; genetics ; Humans ; Male ; Middle Aged ; Mutation ; Protein Precursors ; genetics ; Sequence Analysis ; T-Lymphocytes, Cytotoxic ; metabolism

Ginsenosides are the major components of ginseng, which is known to modulate blood pressure, metabolism, and immune function, and has been used to treat various diseases. It has been reported that ginseng and several ginsenosides have immunoregulatory effects on the innate and T cell-mediated immune response. However, their effects on the humoral immune response have not been fully explored. The present study examined the direct effects of red ginseng extract (RGE) and ginsenosides on mouse B cell proliferation and on antibody production and the expression of germline transcripts (GLT) by mouse B cells in vitro. RGE slightly reduced B cell proliferation, but increased IgA production by LPS-stimulated B cells. Furthermore, ginsenoside Rg1 and 20(S)-Rg3 selectively induced IgA production and expression of GLTalpha transcripts by LPS-stimulated B cells. Collectively, these results suggest that ginsenoside Rg1 and 20(S)-Rg3 can drive the differentiation of B cells into IgA-producing cells through the selective induction of GLTalpha expression.
Animals ; Antibody Formation ; B-Lymphocytes* ; Blood Pressure ; Cell Proliferation ; Ginsenosides ; Immunity, Humoral ; Immunoglobulin A* ; Metabolism ; Mice* ; Panax