Hyperactivity of fibroblasts cultured from psoriatic skin: I. Faster proliferation and effect of serum withdrawal.

Fibroblasts were cultured from the involved and uninvolved forearm skin of patients with severe generalized psoriasis and compared with those from the forearms of normal controls of similar ages. Thirteen strains were obtained from involved skin (PSA strains) and sixteen strains from uninvolved skin (PSB), with thirteen control strains (NSF). Outgrowth of fibroblasts from the psoriatic skin explants was slightly quicker than from control skin and the average proliferation rates of passaged strains were PSA 144, PSB 134 and NSF 94 (P less than 0.05). Psoriatic fibroblasts were abnormally dependent on serum for anchorage. In serum-free medium many cells rounded up and were only loosely attached to the substratum. This effect was rapid, reversible and not corrected by adding fibronectin. Cell attachment assays showed only small differences between the psoriatic and normal fibroblasts and the main effect of serum withdrawal appeared to be on spreading rather than attachment. These data suggest that the dermis of both involved and uninvolved psoriatic skin is abnormal and that the hyperactivity persists in vitro. Our findings seem most compatible with a hyperproliferative reaction of both epidermis and dermis to an extracutaneous, perhaps vascular, stimulus.