Abstract: Objective To investigate the involvement of apoptosis in the lesions of patients with psoriasis. Methods The apoptosis was detected with terminal deoxynucleotidyl transferase mediated dU TP-biotin nick end labeling (TUNEL), and the expression of p53, PCNA and apoptosis-suppressing protein bcl-2 was assessed with immunoperoxidase technique in psoriatic lesions and normal skin. Results A large number of keratinocytes showing biochemical and morphologic features of cells undergoing apoptosis were observed in all the suprabasal layers of the psoriatic epidermis. The plaques from all patients analysed showed marked increase in the number of PCNA positive cells in the middle and basal keratinocytes, and a dramatic reduction in the number of bcl-2 positive cells in the basal cell layer. Conclusion The increased apoptosis of keratinocytes in the lesions of psoriasis might be a homeostatic mechanism to the hyperplasia of cells.

Key words: Psoriasis, Apoptosis, bcl-2