DNA repair and U.V.-light sensitivity of the lymphocytes in discoid lupus erythematosus

Excision repair and cell damage induced by U.V.-light were studied in peripheral lymphocyte cultures derived from patients with discoid lupus erythematosus. Radioactivity was measured by means of a Packard liquid-scintillation counter, cell damage after U.V.-irradiation was estimated by vital staining with trypan-blue and by decrease of the cell-count. Repair incorporation of mostly normal rate could be demonstrated in the lymphocyte cultures of all the 22 patients with discoid lupus erythematosus. The cell damaging effect of U.V.-light was more increased in these cultures than in those of the normal controls. The repair inhibiting effect of chloroquine administered orally in therapeutic doses to the patients was generally slight and incidental. The possible correlation of the findings is discussed