Hyperactivity of fibroblasts cultured from psoriatic skin: II. Synthesis of macromolecules

Glycosaminoglycans and protein synthesis were assessed in fibroblasts cultured from the involved (PSA strains) and uninvolved (PSB strains) forearm skin of patients with severe generalized psoriasis and compared with that in fibroblasts from the forearm skin of control subjects of similar ages (NSF strains). Average rates of glycosaminoglycan secretion were 19% (PSA) and 28% higher (PSB) in psoriatic strains. Although these differences were not significant in themselves, the relationship between glycosaminoglycan secretion and fibroblast density (cells/cm2) was significantly different (P = 0.02) for the psoriatic and control groups, with the psoriatic cells secreting appreciably more glycosaminoglycans at higher cell densities. The nature of the glycosaminoglycans produced was the same in psoriatic and normal strains; 90% was recovered in the culture medium and the bulk of this appeared to be hyaluronic acid with only small amounts of sulphated components. Collagen synthesis was 77% higher in PSA and PSB strains (P less than 0.01), while other protein synthesis was increased by 44% (P less than 0.05). These findings confirm that fibroblasts from psoriatic skin are hyperactive in vitro. The data are compatible with the results of studies of psoriatic skin in vivo and suggest that the entire skin is abnormal.