OBJECTIVETo explore the relationship between Fas-FasL-mediated signal transduction pathway and apoptosis of T lymphocyte subset in ITP patients.

METHODSThe expression rates of membrane Fas, FasL and intracellular activated caspase-3 in peripheral T lymphocyte subset were determined by flow cytometry. T cell subsets with caspase-3 protein expression were detected by Western blot.

RESULTSAs compared with that in healthy control group [(29.4 +/- 8.2)%], the expression rate of membrane Fas on CD4+ T cells was significantly increased in ITP patients [(42.1 +/- 9.5)%] (P < 0.05), however, that on CD8+ T cells was only slightly increased [(9.3 +/- 6.0)% vs (13.4 +/- 5.8)%] with no statistical significance (P > 0.05). The expression rate of FasL on T cell subset in ITP patients was significantly increased (P < 0.05), and that of intracellular activated caspase-3 in T cell subset in ITP patients was notably higher than that in healthy control group (P < 0.05). Western blot analysis showed that the expression of pro-caspase-3 and cleaved-caspase-3 in CD4+ T cells in patients with ITP after treatment were significantly reduced compared with those before treatment (P < 0.05).

CONCLUSIONApoptosis of T lymphocyte subset in ITP patients is accelerated. It is possible that Fas-FasL signal transduction pathway plays an important role in the induction of the apoptosis. The degree of apoptosis of T lymphocytes closely correlates with the disease's activity in ITP patients. Hormone therapy may interfere with Fas-FasL signal transduction pathway of apoptosis.