Interleukin-8 plays its role at local level in psoriasis vulgaris

The pro-inflammatory properties of interleukin-8 (IL-8) suggest a major rol e of this peptide in inflammatory processes of skin and other organs, Both biochemical and immunohistochemical studies from our group have demonstrate d IL-8 peptide within psoriatic scales and epidermis, So far, however, the relevance of circulating IL-8 and its relation to locally produced IL-8 in this disease remain unclear. Serum IL-8 levels of psoriatic patients were d etermined in sandwich-ELISA prior to therapy as well as during therapy. Usi ng either the assay from our laboratory or three commercial ELISAs, no corr elation was found between serum IL-8 levels and disease severity at any sta ge of the disease. Similarly, epidermal IL-8-immunoreactivity was monitored immunohistochemically in sequential biopsies from individual psoriatic les ions as they resolved during the course of therapy, Initially, decreased ep idermal IL-8 immunoreactivity shifted to a homogeneous staining comparable to normal or non-diseased skin as lesions resolved under treatment. These r esults indicate a role of IL-8 at local level in psoriatic skin. In contras t to hyperinflammatory diseases like sepsis, where increased serum IL-8 lev els are found, in psoriasis either circulating IL-8 is absent or potent mec hanisms are operative effectively binding and/or inactivating IL-8 as it en ters circulation.