Interleukin-18 levels in the plasma of psoriatic patients correlate with the extent of skin lesions and the PASI score.

Interleukin-18 is a cytokine with a possible role in the pathogenesis of psoriasis. We examined subpopulations of peripheral blood lymphocytes and their expression of activation markers and correlated this with plasma levels of IL-18 and clinical disease severity in patients with psoriasis. We included 12 patients with psoriasis who had a PASI score from 15 to 48 and compared them to controls. IL-18 plasma concentrations were determined with an enzyme-linked immunosorbent assay. We observed a significant correlation between the IL-18 levels and the area of skin affected with psoriasis and the PASI score. We also observed an increase in NK cells and memory helper CD45RO + /CD4+cells.