Abstract: Objective To study the localization of interleukin-8 (IL-8), HLA-DR, phospholipase A₂ (PLA₂), acid α naphthyl acetate esterase (ANAE), epidermal growth factor receptor mRNA (EGFR mRNA), c fos mRNA in psoriatic skin. Methods Skin lesions of 20 psoriatic cases who received no treatment in previous three months and skin samples of 10 controls were detected by histochemistry, immunohistochemistry and in situ hybridization technique. Results IL-8 was mainly localized at the basal cell layer, spinous cell layer and granular cell layer of the epidermis, the endothelium of the blood vessels and interstitial cells; HLA-DR and ANAE were mainly localized at the infiltrating immune cells in dermis (including T_H cells and mononuclear phagocytes) and the endothelial cells of the blood vessels; PLA₂ reaction was mainly seen at the cytomembrane of keratinocytes in deeper epidermal layers, cornified layer and dermal interstitial cells. All above mentioned positive reactions were more intense, or there were more positive cells in psoriatic lesions than those in controls. c-fos mRNA signal were weaker in lesions than that in controls. EGFR mRNA signal was more intense in lesions, but there was no significant difference between those in the lesions and in controls. Conclusion The results suggest that IL-8 and its mediated inflammatory reactions might play an important role in the development of psoriasis, and it also enhances PLA₂ activity and activates lymphocytes. c fos protooncogene is weakly expressed in proliferative keratinocytes. No distinctive correlation between EGFR mRNA and the development of psoriasis is found.

Key words: Psoriasis, Interleukin-8, HLA-DR, Phospholipases A, Genes,fos, Genes,erbB-1