Objective: To investigate CD28 expression on CD4(+);T cells and its relationship with IFN-γ/IL-10 ration in patients with primary immune thrombocytopenia (ITP) before and after treatment.

Methods: The expression of CD4(+);CD28(+); was detected by flow cytometry, the levels of IFN-γ and IL-10 were determined by double-antibody sandwich ELISA and platelet count was tested by blood cells automatical counter in peripheral blood of 30 patients with ITP before and after glucocorticoid treatment and 26 cases of normal controls. Then the correlations between the outcomes were analyzed.

Results: The expression of CD4(+);CD28(+); of ITP patients before treatment was higher than that of the normal control group (P<0.05), however, after treatment the expression between the two groups had no statistical difference (P>0.05). Compared with the control group, the ITP patients before treatment showed the significantly higher level of IFN-γ and the significantly decreased level of IL-10, and the ratio of IFN-γ/IL-10 was significantly raised (P<0.01); while ITP patients after treatment had no statistically significant difference in the above indexes from the normal controls (P>0.05). Moreover, CD4(+);CD28(+); was positively correlated with IFN-γ/IL-10 ratio (P<0.05), and was negatively correlated with platelet count in ITP patients before treatment (P<0.05).

Conclusions: Co-stimulatory molecule CD4(+);CD28(+); was closely related with immune disorder of ITP. It maybe played a role in the pathogenesis of ITP through involving Th1 advantage state formation.