Objective To investigate the expressions of B7-H1 and PD-1 on peripheral leukocytes from patients with Henoch-Schtmlein purpura(HSP)and their significance.Methods Peripheral leukocytes were obtained from 36 patients with HSP(HSP group)and 24 healthy human controls(control group).Immunofluorescent staining and flow cytometry were used to measure the expressions of B7-H1 and PD-1 on peripheral leukocytes.The expression of both two molecules was compared between the HSP group and control group as well as between patients with Henoch-Sch(o)nlein purpura nephritis(HSPN)(n=9)and those without(n=27).SPSS 12.0 for Windows was used for data analysis.Results The expression rate of B7-H1 on monocytes significantly increased(24.43%±25.79%vs 7.69%±8.31%,t=3.62,P＜0.011),while that of PD-1 decreased(0.84%±1.96%vs 2.28%±1.95%,t=2.78,P＜0.01)in HSP group compared with those in the control group.No significant difference was revealed in the expression of B7-H1 or PD-1 on lymphocytes between HSP group and control group(both P＞0.05).There was a significant increase in the expression of B7-H1 on monocytes(44.81%±12.36%vs 17.63%±25.63%,t=3.05,P＜0.01)and lymphocytes(8.78%±2.10%vs 5.65%±3.96%,t=2.25,P＜0.05)in patients with HSPN compared with those without.Conclusion There is a high expression of B7-H1.but low expression of PD-1 on peripheral blood monocytes from patients with HSP.suggesting that B7-H1 and PD-1 may play a certain role in the Dathogenesis of HSP.