DNA synthesis among uninvolved and involved psoriatic epidermal cells and normal epidermal cells in vitro.

Epidermal cells from 8 patients with psoriasis (involved and uninvolved areas) and from 7 normal individuals, were propagated in vitro. DNA synthesis was determined autoradiographically by measuring the labeling index (1 hr) and a continuous labeling index (72 hr) on 8-10 day old cell cultures. No differences in these 2 kinetic parameters were obtained with respect to involved and uninvolved psoriatic cells. However, when psoriatic cells (involved and uninvolved) were compared to normal cells, the psoriatic cells exhibited a much higher labeling index and continuous labeling index, 200-300% and 60-70% respectively. These data clearly show that in vitro (1) epidermal cells from clinically uninvolved skin of psoriatics proliferate at a rate equal to that of involved psoriatic cells and (2) psoriatic epidermal cells proliferate at a rate greater than normal cells.