DIFFERENT GROWTH-PROPERTIES IN RESPONSE TO EPIDERMAL GROWTH-FACTOR AND INTERLEUKIN-6 OF PRIMARY KERATINOCYTES DERIVED FROM NORMAL AND PSORIATIC LESIONAL SKIN

Epidermal growth factor (EGF) family members and its receptor (EGFR) a re thought to have an important role in the proliferation of epidermal keratinocytes. In this report, we investigated the EGF/EGFR system in primary keratinocytes derived from normal and psoriatic lesional skin . EGF elicited the growth of both normal human keratinocytes (NHKs) an d psoriatic lesional keratinocytes (PLKs). Interleukin-6 (IL-6) potent iated the EGF-dependent dent growth of NHKs, but has no observable eff ect on PLKs, while IL-6 itself showed no growth-stimulating activities in both cell types. Immunodetection and in situ hybridization analyse s revealed that IL-6 induces EGFR expression in NHKs in a time-and dos e-dependent manner. This EGFR expression decreased reversibly to an un detectable level when IL-6-treated NHKs were re-cultured in IL-6-free conditions. On the other hand, PLKs expressed high levels of EGFR even when unstimulated and the expression level was not affected by IL-6 s timulation. These results suggest that the EGF/EGFR system is involved in the growth of NHKs and PLKs and that IL-6 potentiates NHK growth p artly through the induction of EGFR, The different EGFR regulatory sys tem may contribute to the pathogenesis of psoriasis. (C) 1998 Elsevier Science Ireland Ltd.