AN INCREASED RATIO OF INTERLEUKIN-1 RECEPTOR ANTAGONIST TO INTERLEUKIN-1-ALPHA IN INFLAMMATORY SKIN DISEASES

IL-1 receptor antagonist (IL-1ra) is a cytokine that competitively bin ds the IL-1 receptor to antagonize IL-1 activity without any agonist f unction. Previous experiments indicated that the ratio of IL-1ra to IL -1 alpha in the normal stratum corneum (SC) was much higher in the sun -exposed face than in the sun-protected area, upper arms. It was also reported by another laboratory that IL-1ra is increased in the lesiona l skin of psoriatic patients. This study was designed to measure the c ontents of IL-1 alpha and IL-1ra in non-lesional and pathological SC o btained from inflammatory skin diseases including psoriasis and non-ps oriatic dermatoses such as atopic dermatitis. The SC materials were ob tained with a noninvasive tape-stripping method. Their soluble fractio ns were prepared and assayed for IL-1 alpha and IL-1ra by enzyme-linke d immunosorbent assays. As a result we confirmed the previous findings that the ratio of IL-1ra to IL-1 alpha in the normal SC was much high er in the face than in the sun-protected sites, the trunk as well as e xtremities. Next, we found that IL-1 alpha contents were significantly reduced in the SC samples obtained from inflammatory skin regardless of whether their IL-1ra contents increased or unchanged. Moreover, we noted that an increased ratio of IL-1ra to IL-1 alpha in the SC was no t specific to psoriasis, but was also found in other inflammatory skin diseases including atopic dermatitis. This ratio was found to become lower after successful treatment of these skin lesions with topical gl ucocorticoids. We conclude from these observations that the increased ratio of IL-1ra to IL-1 alpha in the SC is a non-specific phenomenon t hat can occur in any inflammatory skin diseases regardless of the infl ammatory pattern, probably reflecting a skin regulation process agains t various kinds of inflammation.