Inflammatory cytokines and their receptors in psoriatic skin : emphasis on the epidermal interleukin 1 system

Nearly two centuries have passed since the first accurate description of psoriasis by Wilan in the year 1808. Psoriasis is a common, well-defined skin disease featuring the interplay of genetic, environmental, and immunological factors. Extensive reviews on psoriasis are given elsewhere. Despite numerous reports, the exact etiology is still unknown. Moreover, 70 % of psoriatic patients are not satisfied with the currently available anti-psoriatic treatments (Gottlieb AB, oral presentation, Psoriasis Meeting, Dec 4-5 1995, Lake Buena Vista, FL), which stresses the contemporary societal interest of psoriasis research. Recent studies have identified a dysregulated crosstalk between resident skin cells and infiltrating leukocytes in psoriasis. Several lines of evidence point to the cytokine interleukin 1 (IL-l) as an integral component of the cellular immune basis of psoriasis. The regulation of cytokine activity in general, and that of epidermal IL-l in particular, is described in chapter 1.1. Skin as a site of immune responses, exemplified by the cutaneous inflammatory response, is described in chapter 1.2. Finally, the cellular immunopathogenesis of psoriasis, with special emphasis on IL-l, is reviewed in chapter 1.3.