Abstract: Objective To investigate the expression and distribution of cellular FLICE-inhibitory protein （c-FLIP） in peripheral blood and lesions of psoriatic patients. Methods Peripheral blood and skin samples were obtained from 30 patients with psoriasis vulgaris and 20 normal controls. Flow cytometry was used to detect intracellular c-FLIP protein in peripheral T and B lymphocytes, immunohistochemistry to examine the expression of c-FLIP in lesional tissue. Results Based on the positivity rate of c-FLIP, there was a significant increase in T lymphocytes in active psoriasis compared with regressive psoriasis and normal controls （6.32% ± 1.17% vs 2.64% ± 0.74% and 2.28% ± 0.54%, P < 0.01 and 0.05, respectively）, while no significant difference was found in B lymphocytes among these three groups（0.78% ± 0.16%, 0.71% ± 0.32%, 0.69% ± 0.18%, respectively, P > 0.05）. The expression intensity of c-FLIP in keratinocytes was also higher in active psoriasis than in regressive psoriasis and normal controls （89.73 ± 5.24 vs 117.40 ± 7.50, 121.58 ± 7.93, P < 0.01 and 0.05 respectively）, and there was no difference between regressive psoriasis and normal controls （P > 0.05）. Conclusions c-FLIP is highly expressed in lesions and peripheral T lymphocytes of patients with active psoriasis, suggesting the possible involvement of c-FLIP in the proliferation of T lymphocytes in psoriasis.

Key words: c-FLIP, Psoriasis, Apoptosis, Proliferation