The Expression And Regulation Of FcγrⅡb On B Cells From PSS Patients

PART ONEExpression of FcyRIIb on peripheral B cells in patients with primary Sjogren’s syndrome and its clinical significanceObjective To investigate the expression of FcyRIIb on peripheral B cells and its clinical significance in primary Sjogren’s syndrome (pSS).Method FcyRIIb expression on peripheral B cells from19pSS patients and15healthy controls was examined by flow cytometry. The levels of serum ant-SSA and SSB antibodies were determined using enzyme-linked immunosorbent assay (ELISA). Data were analyzed with t test and Pearson correlation test.Results The percentage of memory CD19+CD27+B cell subpopulation was significantly lower in pSS patients [(20.8±2.7)%] compared to normal controls [(37.8±2.2)%](p<0.01). The level of expression of FcyRIIb in active pSS memory CD19+CD27+B cells [MFI(74.1±8.4)] was significantly reduced compared to inactive [MFI(131.8±11.0)](p<0.01) and normal controls [MFI(138.8±12.2)](p<0.01). The level of expression of FcγRⅡb on memory CD19+CD27+B cells from pSS patients was inversely correlated with Sjogren’s syndrome disease activity index (SSDAI)(r=-0.744, p=0.0003). pSS patients in serum anti-SSA/SSB antibodies positive group [MFI(74.6±3.1),(48.5±6.8)] displayed a lower expression of FcyRIIb on memory CD19+CD27+B cell than patients in serum anti-SSA/SSB antibodies negative group [MFI(122.50±10.84),(107.9±8.95)](both p<0.01).The level of expression of FcγRⅡb in active pSS memory CD19+CD27+B cells was inversely correlated with anti-SSA antibody titers(r=-0.685, p=0.014).Conclusion The expression of FcγRⅡb on peripheral memory B cells from active pSS patients is inversely correlated with SSDAI and is also inversely associated with anti-SSA antibody levels. Decreased expression of FcγRⅡb might play an important role in the pathogenesis of pSS. Objective To detect the regulative effect of high-dose methylprednisolone (HD-MP) therapy and bone marrow mesenchmal stem cells (BM-MSCs) on the expression of FcyRIIb on B cells.Methods FcyRⅡb expression on peripheral B cells from6pSS patients with serious thrombocytopenia was examined by flow cytometry(FCM). After a three-day HD-MP therapy, they were further assessed for FcyRIIb changes on their peripheral B cells. BM-MSCs from female C57BL/6mice were isolated and expanded. The surface phenotypes were detected by FCM. B cells were separated from the spleen of female C57BL/6mice by magnetic beads. B Cells were cocultured with MSCs for72days at the ratio from1:1to1:100. The effect of MSCs on the expression of FcyRIIb on B cells were evaluated by FCM.Results After a three-day HD-MP therapy, the percentages of B cell subsets had no changes, but the expression of FcyRIIb on memory B cells and plasmablasts was significantly increased, meanwhile with raised number of platelet. After72hours of coculture, MSCs significantly induced the expression of FcyRIIB on B cells at the B-cell/MSC ratio of1:1(P<0.05), this effect was detectable at a1:10and1:100, but with no significant difference (P>0.05).Conclusion HD-MP and BM-MSCs could induce the expression of FcyRIIb on B cells. Mechanism involved in this effect needs further study.