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Objective:To explore the distribution characteristics of memory B cells and its relationship with bone erosion in patients with rheumatoid arthritis (RA), and to further understand the mechanism of B cells in the pathogenesis of RA.Methods:B cell subsets in peripheral blood of 200 RA patients and 50 healthy individuals were detected by flow cytometry. According to the surface markers CD19, CD27 and lgD, B cells were divided into CD19 +CD27 +lgD - switched memory B cells, CD19 +CD27 +lgD + non-switched memory B cells, CD19 +CD27 -lgD - double-negative memory B cells and CD19 +CD27 -lgD + naive B cells. B cells in RA patients with various disease activity score, course of disease and treatment were analyzed. Patients were divided into four groups according to the results of joint ultrasonography, including patients without bone erosion, patients with hand bone erosion, patients with knee bone erosion and patients with hand and knee bone erosion. The relationship between the distribution of B cell subsets, autoantibodies and RA bone erosion were analyzed. Differences between the groups were analyzed by independent-samples t test, Mann-Whitney U test and χ2 test. The analysis of variance, Kruskal-Wallis analysis were used for multi-group comparison, Spearman correlation analysis was also used for correlation analysis. Results:①RA patients showed significantly decreased non-switched memory B cells [(9.5±6.7)% vs (12.1±4.7)%, t=2.46, P=0.015] and increased double negative memory B cells [(3.8±2.5)% vs(2.7±1.3)%, t=-4.74, P<0.001] in comparison to healthy individuals. The percentage of non-switched memory B cells were decreased in RA patients with moderate disease activity [(8.4±4.7 )% vs (12.4±7.5)%, t=3.13, P=0.001] and high disease activity [(7.8±7.6)% vs (12.4±7.5)%, t=3.00, P=0.003] in comparison to those in RA patients who achieved remission. Meanwhile, the na?ve B cells [(70.3±15.0)% vs (63.9±14.6)%, t=-2.15, P=0.034] were increased in RA patients with moderate disease activity. No difference was found in RA patients with different disease courses. Total B cells [(4.8±2.9)% vs (7.2±4.1)%, t=-3.24, P=0.001], non-switched memory B cells (7.6±4.3)% vs (10.0±7.1)%, t=-2.63, P=0.010) in RA patients who received prednisone treatment were decreased, while double-negative memory B cells (4.9±3.0)% vs (3.6±2.3)%, t=-2.79, P=0.006] were increased compared with those in RA patients without prednisone treatment. Non-switched memory B cells was decreased in RA patients with hand and knee erosion compared with RA patients without erosion [6.8%(2.5%, 9.5%) vs 9.7%(5.5%, 17.5%), Z=-2.12, P=0.034]. Double negative memory B cells in subgroup with keen erosion [3.3%(2.7%, 5.0%) vs 2.6%(1.9%, 3.8%), Z=-2.09, P=0.036]as well as with hand and knee erosion [3.9%(2.3%, 5.6%) vs 2.6%(1.9%, 3.8%), Z=-2.41, P=0.016] were higher than those in patients without erosion. In addition, higher serum RF level was found in subgroup RA patients with hand and knee erosion compared with subgroup of RA patients without erosion [141.0 (38.0, 874.0) U/ml vs 53.5 (10.0, 106.0)U/ml, Z=-2.07, P=0.039]. Meanwhile, the positive rate of ACPA in RA patients with bone erosion of hand was significantly higher than that of RA patients without bone erosion [81%(52/64) vs 64%(38/59), χ2=4.44, P=0.043). Conclusions:The results suggest that the increase of double negative memory B cells, the decrease of non-switched memory B cells and higher level of autoantibodies may closely relate to bone erosion of RA, which may be one of the pathogenesis of disability in RA.
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We aimed to express and purify three rabies virus glycoproteins with different tags and sizes. After analyzing their binding function, we wish to obtain a rabies virus glycoprotein with higher affinity and ability to specifically bind memory B cells. Experiments were carried out to express full length, as well as the ectodomain RVG by gene engineering method. Combined with the antibody of CD19 and CD27, the candidate protein labeling with fluorescence was used to analyze its binding function. Flow cytometry was used to detect the anti-rabies virus specific memory B cells in PBMCs, and confirm the binding ability between the candidate proteins and anti-rabies virus-specific memory B cells. We successfully constructed three expression vectors pGEX-5X-1-RVG, pET28a-RVG and pET30a-G. Three glycoproteins GST-RVG, His-RVG and His-G were obtained by optimized expression and purification conditions. The antigen specificity of purified GST-RVG, His-RVG and His-G were identified by Western blotting and ELISA. The affinity of these three purified glycoproteins to anti-rabies virus antibody were detected by competitive ELISA. Anti-rabies virus specific memory B cells in positive PBMCs gained from people who had ever been injected with the vaccine can be detected by flow cytometry. Thus, we got a recombinant rabies virus glycoprotein that had high-affinity and could sort antigen specific memory B cells.
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Objective To investigate the characteristics and the frequencies of B cell subsets in peripheral blood of rheumatoid arthritis (RA) patients,and to study the correlation between B cell subsets and clinical indices and influence of different therapies on B cell subsets to deeply understand the pathogenesis of RA.Methods Peripheral blood witched memory B cells,non-switched memory B cells,naive B cells,and double negative B cells of 141 patients and 33 healthy controls were measured by flow cytometry.Patients were divided into three groups based on their therapeutic regimen,including tumor necrosis factor-or (TNF-α) inhibitors combined with disease modifying antirheumatic drugs (DMARDs),DMARDs only and patients without any therapy.The relevance between B cells subsets and clinical manifestations,lab test results exemption were assessed as well as the influence of different therapies.All data were were analyzed by Statistical product and service solutions (SPSS) 23.0 statistical analysis for unpaired t test,analysis of variance and Spearman's correlations analysis.Results ① New-onset RA patients with less than 12 weeks disease duration and never accepted any drugs had a significantly lower frequency of peripheral blood memory B cells,including non-switched memory B cells [(8 ±4)％ vs (13 ±4)％,P＜0.05,t =3.3)] and switched memory B cells [(18±10)％ vs (23±7)％,P＜0.05,t=2.2)],than healthy individuals.② There was a negative association between non-switched memory B cells and disease activity score in 28 joints (r=-0.23,P＜0.05).③ Negative association between non-switched memory B cells and erythrocyte sedimentation rate (ESR),lgG was found,while therewas no association between pre-switched B cells and other laboratory test results.④ Non-switched memory B cells and switched memory B cells increased after TNF-α arntagonist or DMARDs therapy.Conclusion The results of this study suggest that B cell abnormalities in new-onset RA patients with short disease duration are reduced non-switched memory B cells and switched memory B cells.A negative correlation has been found between non-switched memory B cells and ESR and lgG.B cells subsets frequency are changed by TNF-α antagonist and DMARDs,which suggests that changes of B cell subsets may contribute to the occurrence and development of RA.
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Objective Rapid elevation of the IgG antibody against Candida Enolase ( Eno ) has been observed in patients with invasive candidosis in an early stage .The present study was to confirm the association of Candida colonization with humoral im-mune anamnestic response of the dominant antigen . Methods Twenty-four mice were randomized into group 1 treated by oral Candi-da colonization plus intraperitoneal infection ( immunocompetent , n=8) , 2 treated with immunosuppressant in addition to the treatment of group 1 ( immunocompromised , n=8) , 3 treated by oral Candida colonization only ( immunocompetent , n=4) and 4 treated by in-traperitoneal injection only( immunocompetent, n=4).The number of Eno-specific memory B-cells in the spleen and the levels of IgG , IgM and IgA antibodies were determined in the peripheral blood of the immunocompetent and immunocompromised invasive candidiasis mice . Results At 7 days after invasive infection , there were significantly more Eno-specific memory B-cells in the mice of groups1 ( 47.25 ± 13.81) and 2 (43.14±15.95) than in groups 3 (8.00±3.74) and 4(8.50±2.38) (P0.05).Eno-IgG antibodies were detected in the serum of the mice of the first two groups in the early stage of invasive infection and positively corre -lated with antigen-specific memory B-cells (r=0.737,P <00.1 ). Conclusion Rapid elevation of the Eno-IgG antibody level in the early stage of invasive infection after Candida colonization may be attributed to the rapid proliferation of humoral immune memory cells.
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Anthrax is a highly lethal infectious disease caused by the spore-forming bacterium Bacillus anthracis. The major virulence factor of B. anthracis consists of protective antigen (PA), lethal factor (LF) and edema factor (EF). PA binds with LF to form lethal toxin (LT), and PA binds with EF to form edema toxin (ET). Antibiotics is hard to work in advanced anthrax infections, because injuries and deaths of the infected are mainly caused by lethal toxin (LT). Thus, the therapeutic neutralizing antibody is the most effective treatment of anthrax. Currently most of the anthrax toxin antibodies are monoclonal antibodies (MAbs) for PA and US FDA has approved ABTHRAX humanized PA monoclonal antibody for the treatment of inhalational anthrax. Once B. anthracis was artificially reconstructed or PA had mutations within recognized neutralization epitopes, anti-PA MAbs would no longer be effective. Therefore, anti-LF MAbs is an important supplement for anthrax treatment. Most of the anti-LF antibodies are murine or chimeric antibodies. By contrast, fully human MAbs can avoid the high immunogenicity of murine antibodies. First, we used LF to immunize the transgenic mice and used fluorescent cell sorting to get antigen-specific memory B cells from transgenic mice spleen lymphocytes. By single cell PCR method, we quickly found two strains of anti-LF MAbs with binding activity, 1D7 and 2B9. Transiently transfected Expi 293F cells to obtain MAbs protein after purification. Both 1D7 and 2B9 efficiently neutralized LT in vitro, and had good synergistic effect when mixed with anti-PA MAbs. In summary, combining the advantages of transgenic mice, fluorescent cell sorting and single-cell PCR methods, this study shows new ideas and methods for the rapid screening of fully human monoclonal antibodies.
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BACKGROUND/AIMS: Inflammatory bowel disease (IBD) is a chronic disease of the gastrointestinal tract, whose etiologies are still unknown. This study was performed to evaluate the humoral immune response in terms of B cell functions in selected IBD patients. METHODS: Eighteen pediatric patients with IBD, including 12 cases of ulcerative colitis (UC) and six with Crohn disease (CD), were enrolled in this study. The pneumococcal vaccine was injected in all patients, and the IgG antibody level to the polysaccharide antigen was measured before and 4 weeks after injection. The B cell switch-recombination process was evaluated. RESULTS: Five patients with IBD (three CD and two UC) had defects in B cell switching, which was significantly higher than in controls (p=0.05). Ten patients had a specific antibody deficiency and exhibited a higher frequency of bacterial infection than the healthy group. The mean increased level of IgG after vaccination was lower in IBD patients (82.9+/-32.5 microg/mL vs 219.8+/-59.0 microg/mL; p=0.001). Among the patients who had an insufficient response, no significant difference in the number of switched memory B-cell was observed. CONCLUSIONS: A defect in B lymphocyte switching was observed in pediatric IBD patients, and especially in those patients with CD. Owing to an increased risk of bacterial infections in those patients with antibody production defects, pneumococcal vaccination could be recommended. However, not all patients can benefit from the vaccination, and several may require other prophylactic methods.