IL-1 alpha, IL-1 beta and psoriasis: conflicting results in the literature. Opposite behaviour of the two cytokines in lesional or non-lesional extracts of whole skin.

A still debated question in the field of the cytokine network in psoriasis is represented by contrasting data reported on the local amount of IL-1 beta amounts, of IL-1 in this dermatosis. In fact previous studies have suggested that there were decreased Il-1 alpha amounts at the lesional level but increased nonfunctional IL-1 beta concentrations as compared to the non-lesional and normal epidermis. However, recent data suggest that IL-1 alpha and, to a lesser extent, IL-1 beta amounts, are both increased and biologically active in the epidermal cell suspension of lesional psoriatic skin as compared to those of normal skin. The data reported in the present paper show that IL-1 alpha levels are decreased in psoriatic lesional extracts of whole skin (mean 2.9 +/- 2 pg/mg) as compared to non-lesional (mean 6.7 +/- 6.2 mg/mg; p = 0.02) or normal skin (mean 13.8 +/- 9.4 pg/mg; p = 0.0002). IL-1 alpha concentrations were also significantly lower in the non-lesional skin than in normal skin (p = 0.02). In contrast, the IL-1 beta levels (mean 1.2 +/- 0.74 pg/mg were higher in the lesional samples than in the non-lesional ones (mean 0.5 +/- 0.4 pg/mg; p = 0.0004) or in normal skin (mean 0.4 +/- 0.2 pg/mg; p = 0.004). No differences in IL-1 beta levels were observed between non-lesional and normal skin (p = 0.3). In addition both IL-1 alpha and IL-1 beta are directly correlated with the disease severity and each other. Our data, extending the Il-1 determination to the whole skin, seem to confirm the previously reported findings at the epidermis level and provide new light on possible interpretation of literature discrepancies.