Comparisons of in vivo and in vitro photosensitivities and DNA repair in fibroblast and keratinocyte cells.

Minimal erythema dose of ultraviolet light correlated significantly with the UV-sensitivity of fibroblast cells from 5 patients with xeroderma pigmentosum, 13 patients with keratinocytic neoplasms of the skin, and 21 control subjects, but not with that of cells from 6 patients with photosensitive dermatitis. In unscheduled DNA synthesis after UV irradiation, the number of grains per nucleus was much less in keratinocytes than in fibroblasts, but the relative dose-response relationship was similar. This indicates that keratinocytes can also be used in vitro UV-sensitivity studies.