Abstract: Objective To study the relationship between apoptosis regulation and epidermal proliferation in psoriasis. Methods The expression of apoptosis molecule PDCD5 (programmed cell death 5) on psoriatic lesions was observed by direct immunofluorescence. The positive rates and the average of fluorescence intensity of PDCD5 were analyzed quantitatively with FACS and computer CELL Quest software. The expression of PDCD5 mRNA in psoriatic lesions was detected by RT-PCR. Results The expression of PDCD5 protein was obviously lower in psoriatic epidermal cells than that of the normal skin. The positive rate and the average fluorescence intensity of PDCD5 in psoriatic epidermal cells were notably lower than those of the normal skin (P<0.01). The expression of PDCD5 mRNA in psoriatic lesions was lower than that of the normal skin. Conclusions The epidermal over-proliferation of psoriatic lesions is correlated with the down-regulation of apoptosis molecule PDCD5 expression, which indicates an abnormal regulation of epidermal cell differentiation.

Key words: Psoriasis, Keratinocytes, Apoptosis