Abstract: Objective To study the relationship between cell apoptosis and psoriasis. Methods The expression of Bax, Fas and Fas-L was studied with immunohistochemical technique(SP), and apoptosis was detected with terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay in lesional and non-lesional psoriatic skin. Results In comparison with normal skin, there was an over-expression of Bax, Fas and Fas-L in epidermal keratinocytes, inflammatory cells and vascular endothelium in psoriatic skin, and accompanied with up-regulation of apoptosis. The above abnormalities were not corrected completely after effective treatment in some cases. Conclusions The increase of apoptotic keratinocytes is possibly one kind of internal homeostatic mechanism against the hyperplasia of epidermal cells, and might relate to abnormal expression of apoptosis-associated proteins Bax, Fas and Fas-L. The Fas system might also take part in unusual local immunoreaction in psoriasis.

Key words: Psoriasis, Apoptosis, Bax Antigens, CD95 Fas-L