[Influence of Costimulatory Signaling Molecules on Immun Functons of B Lymphocytes in Patients with Immune Thrombocytopenia]

To explore the effect of costimulatory signaling molecules (CD80, CD86) expression on the quantity and function of B lymphocytes in peripheral blood (PB) of the patients with immune thrombocytopenia (ITP).A total of 55 ITP patients (30 cases were newly diagnosed and 25 cases were in remission), 25 healthy volunteers as controls were enrolled in this study. The levels of CD19(+)CD5(+), CD19(+)CD80(+), CD19(+)CD86(+), CD41a(+)IgG, CD41a(+)IgM and IgG, IgM in CD19(+)B cells were measured by flow cytometry (FCM). The correlation of CD19(+)B cells with clinical parameters of ITP patients was analyzed.The level of B1 (CD19(+)CD5(+)) of newly diagnosed ITP patients was significantly higher than that of remitted ITP patients and controls (P0.05). The level of CD19(+)CD80(+) of newly diagnosed ITP patients was significantly higher than that of remitted ITP patients and controls (P0.05). And the expression of IgG and IgM in CD19(+)B cells of newly diagnosed ITP patients was significantly higher than that of remitted ITP patients and controls (P0.05). The levels of IgG and IgM in remitted ITP patients after treatment were significantly lower than that before treatment (P0.05). The level differences of IgG and IgM before and after treatment in refractory ITP patients were not statistically significant (P0.05). The expression of CD19(+)CD80(+) in newly diagnosed ITP patients positively correlated with the level of Th1 and Th1/Th2 (r=0.502, r=0.471, P0.05). The expression of CD19(+)CD80(+) of newly diagnosed ITP patients positively correlated with the level of IgG and IgM in CD19(+)B cells (r=0.552, r=0.467, P0.05), and negatively correlated with PB platelet count (r= -0.424, P0.05). The levels of IgG and IgM in CD19(+)B cells of newly diagnosed ITP patients negati- vely correlated with PB platelet count (r=-0.658, r=-0.526, P0.05).The enhacement of costimulatory signaling pathway of CD19(+)B cells in ITP patients results in the abnormal activation of B lymphocytes, thereby mediates the dysfunction of immune system and involves in the pathogenesis of ITP.