Abstract: Objective To investigate the alteration of T-lymphocyte subsets in splenic tissue and its clinical significance in patients with immune thrombocytopenic purpura (ITP).Methods Forty-seven patients with ITP treated in our department between December 2005 and May 2008 were recruited and allocated into the steroid-dependent group (SD group, n=29) and the steroid-resistant group (SR group, n= 18).Another 12 patients who underwent emergent splenectomy for traumatic spleen rupture were selected as controls.The expressions of CD3~+ cells, CD4~+ cells and CD8~+ cells in the specimens of the splenic tissue were detected by immunohistochemistry.The percentage of the positive staining cells around the periarterial lymphatic sheath (PALS) of the spleen was counted under the microscope.The ratio of CD4~+ cells and CD8~+ cells was calculated.The differential percentage of CD3, CD4 and CD8 positive ceils and CD4~+/CD8~+ ratio of 3 groups were analysed.Results No significant difference of the percentage of CD3~+ and CD4~+ cells in PALS was found among 3 groups (all P>0.05).The percentage of CD8~+ cells in PALS of control group was significantly lower than that in SD group and SR group (28.70±22.19 vs 43.80±20.77, 49.27±14.10, both P<0.05), and the CD4~+/CD8~+ ratio in PALS of control group was higher than that in SD group and SR group (6.27±4.64 vs 0.95±0.93, 0.89±0.51, beth P<0.05).There was no significant difference in the percentage of CD8~+ cells and the ratio of CD4~+/CD8~+ in PALS between SD and SR group (both P>0.05).Conclusions Abnormal cellular immunity of spleen is found in patients with ITP.No significant association is found between pre-operative response to steroids and alteration of T-lymphocyte subsets in the spleen.