Abstract
The responsiveness of psoriatic epidermal cells to 1α,25-dihydroxyvitamin D3 (1α,25(OH)2D3) was examined in explant-outgrowth cultures of involved and uninvolved skin of five patients with psoriasis vulgaris. A feeder layer was required for outgrowth of psoriatic epidermal cells of involved skin but not for that of cells of uninvolved skin. Normal epidermal cells were sensitive to inhibition by 1α,25(OH)2D3 and the number of DNA synthesizing cells, determined by autoradiographs, was reduced to about 15% of that of the controls by 1 nM 1α,25(OH)2D3. Psoriatic epidermal cells isolated from both involved and uninvolved skin were more resistant, and 1α,25(OH)2D3 at two orders of magnitude with higher concentrations was required to inhibit their DNA synthesis.
