Interleukin 1 alpha, tumor necrosis factor alpha, and interferon gamma in psoriasis

Although recent studies have suggested that a variety of cytokines released by keratinocytes and inflammatory leukocytes could contribute to induction or persistence of the inflammatory processes in psoriasis, it remains unclear how production of these cytokines is regulated in psoriatic patients. To elucidate the biologic relevance of these cytokines to the pathogenesis of psoriasis, we investigated serum levels of interleukin 1 alpha, tumor necrosis factor alpha, and interferon gamma in 21 patients with psoriasis vulgaris, together with 21 healthy controls. The mean serum levels of interleukin 1 alpha and tumor necrosis factor alpha were not significantly different from those in controls, while those of interferon gamma were significantly elevated in the patients with psoriasis. Serum levels of interleukin 1 alpha correlated negatively with clinical disease severity expressed as psoriasis area and severity index score and with duration of psoriasis. In contrast, interferon gamma levels were related, although not significantly, to disease severity. In addition, an inverse correlation was noted between the interleukin 1 alpha levels and interferon gamma levels. These results indicate that interleukin 1 alpha and interferon gamma may be relevant to the induction and perpetuation, respectively, of the inflammatory responses in psoriasis, and that these cytokines, which have similar biologic properties, may strictly regulate one another's production in vivo.