Abstract: Objective To study the mode of action of cytotoxic T lymphocytes in psoriasis and lichen planus by detecting Fas-L and perforin in the two diseases. Mehtods Immunohistochemical staining ABC method was used. Results Both Fas-L and perforin were positive expressed in psoriasis. Fas-L was not expressed and perforin was expressed in lichen planus. Conculsion Cytotoxic T lymphocytes might played a role through both Fas-L and perforin pathways in psoriasis. However, cytotoxic T lymphocytes might function through perforin pathway only.

Key words: Psoriasis, Lichen planus, Fas ligand, Perforin