Cytokines in skin lesions of psoriasis.

Cytokine levels were compared in aqueous extracts of stratum corneum from psoriatic lesions and normal heel. Samples from heel contained high levels of interleukin-1 alpha (IL-1 alpha) and beta measured in immunoassays, although only the IL-1 alpha was biologically active. No other cytokines could be detected in heel samples. Interleukin-1 (IL-1) levels were dramatically reduced in lesional samples. A neutrophil chemoattractant was found in all lesional extracts, and was demonstrated to be mainly interleukin-8 (IL-8) using a specific neutralizing antiserum. Tumor necrosis factor alpha (TNF-alpha) and beta (TNF-beta), and interferon alpha (IFN-alpha) and gamma (IFN-gamma) were detected in lesional extracts using immunoassays, however, no equivalent biological activities could be detected. Interleukins 2 (IL-2), 4 (IL-4), and 6 (IL-6), granulocyte and granulocyte/macrophage colony stimulating factor (GM-CSF), could not be detected in any samples. IL-8 is therefore the only biologically active cytokine shown in this study to be elevated in psoriatic lesional extracts, and may therefore play a role in the pathogenesis of the disease.