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

Objective: 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).

Methods: 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.

Results: The level of B1 (CD19(+)CD5(+)) of newly diagnosed ITP patients was significantly higher than that of remitted ITP patients and controls (P<0.05). The level of CD19(+)CD80(+) of newly diagnosed ITP patients was significantly higher than that of remitted ITP patients and controls (P<0.05). 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 (P<0.05). The levels of IgG and IgM in remitted ITP patients after treatment were significantly lower than that before treatment (P<0.05). The level differences of IgG and IgM before and after treatment in refractory ITP patients were not statistically significant (P>0.05). 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, P<0.05). 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, P<0.05), and negatively correlated with PB platelet count (r= -0.424, P<0.05). 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, P<0.05).

Conclusion: 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.