The pathogenesis of vasculitis is complex and is yet to be fully elucidated, although it is known that inflammatory cells play a major role. Dysregulation of apoptosis and defective clearance of inflammatory cells could lead to the persistence of inflammation and excessive tissue injury. In this study we aimed to investigate Fas (CD95) and apoptosis on peripheral blood (PB) neutrophil and lymphocytes in Henoch-Schonlein purpura, both in the acute phase and after resolution to determine the role of apoptosis in this self-limited vasculitis. Leukocytoclastic vasculitis presenting with Henoch-Schonlein purpura (HSP) was diagnosed according to ACR 1990 criteria and confirmed by skin biopsy. Thirty-seven patients (22 boys, 15 girls) aged 2.5-17 years (9 +/- 3.3) were enrolled in the study. Expression of CD95 and apoptosis were investigated by the annexin/PI method on peripheral blood neutrophils and lymphocytes in both the acute and the resolution phases of the disease. The mean neutrophil and lymphocyte CD95 expression was 65.4 +/- 37.6% and 33.3 +/- 7.3%, respectively, in the acute stage and 62.8 +/- 44.2% and 41 +/- 20%, respectively, in the resolution (P > 0.05). The percentage of apoptotic peripheral blood neutrophils and lymphocytes as determined by annexin positivity was 13.3 +/- 11.31% and 8.6 +/- 9.5%, respectively, during the acute phase and 4.6 +/- 1 3.4% and 3.1 +/- 3.1%, respectively, in the resolution (P = 0.002, P = 0.008). These results suggest that increased apoptotic process in the immune effector cells in the acute phase of the disease may play an important role in the early control of inflammatory response and repair in leukocytoclastic vasculitis, thereby contributing to the self-limited nature of the disease.