Polarization and apoptosis of T cell subsets in idiopathic thrombocytopenic purpura

It is well-known that idiopathic thrombocytopenic purpura (ITP) is an acquired organ-specific autoimmune hemorrhagic disease and dysfunctional cellular immunity is considered important in the pathophysiology of ITP. However, polarization patterns and apoptosis profiles of T lymphocytes remain unclear. In this study, we investigated the polarization of T cell subsets, the expressions of apoptotic proteins Fas/FasL on the subsets and the level of anti-apoptotic gene bcl-2 and bax mRNA. It was demonstrated that the ratios of Th1/Th2 and Tc1/Tc2 in ITP children were increased obviously and that the average percentages were increased clearly for Th1 and Th2, but not for Tc1 and Tc2. In ITP children, the enhancing expressions were detected for FasL on Th1 and Tc1 and for Fas on Th2 and Tc2. With increasing level of bcl-2 mRNA and decreasing expression of bax mRNA in ITP children, the ratio of bcl-2/bax mRNA was improved obviously, which was positive correlated with the ratio of Th1/Th2. Taken together, our findings indicate that ITP is a Th1 predominant disease. This polarization pattern of T cell subsets might be related to the high ratio of bcl-2/bax mRNA and the abnormal expressions of Fas and FasL on T cell subsets.