Overexpression of monocyte-derived cytokines in active psoriasis: a relation to coexistent arthropathy

An overexpression of inflammatory cytokines has been found in the lesional skin as well as peripheral blood in patients with psoriasis, although its e tiological significance is not yet understood. In order to evaluate the cel l type responsible for the elevated cytokines in the peripheral blood, we i nvestigated cytokine profiles of the fractionated peripheral blood mononucl ear cells (PBMCs) in 30 patients with psoriasis and 27 healthy controls. Wi thout stimulation, higher levels of interleukin (IL)-1 beta, IL-6, and IL-8 were produced by freshly isolated PBMCs from the patients than those from the controls. In the fractionated PBMCs, the monocyte-rich fractions were m ainly responsible for the production of these cytokines and mRNA. The eleva ted levels of monocyte-derived cytokine mRNAs decreased following successfu l treatment with cyclosporin A. Although no correlation was found between t he cytokine levels and the psoriasis area and severity index (PASI) scores, patients with arthropathy showed significantly high production levels of I L-1 beta, IL-6, and IL-8. These findings suggest that monocytes are the maj or cell source producing inflammatory cytokines in the peripheral blood of psoriasis, and the increased cytokine levels are related to the coexistent arthropathy rather than the severity of cutaneous lesions. (C) 1999 Elsevie r Science Ireland Ltd. All rights reserved.