Studies of DNA and chromosome damage in skin fibroblasts and blood lymphocytes from psoriasis patients treated with 8-methoxypsoralen and UVA irradiation.
Exposure of human lymphocytes and skin fibroblasts in vitro to a single, clinically used dose of PUVA, i.e., 0.1 micrograms/ml of 8-methoxypsoralen (8-MOP) plus 0.9-4 J/cm2 of longwave ultraviolet radiation (UVA), lead to the formation of DNA damage as determined by alkaline elution, and to chromosome aberrations and sister chromatid exchanges (SCE). When lymphocyte-enriched plasma was obtained from psoriasis patients 2 h after oral intake of 8-MOP and then UVA irradiated (1.8-3.6 J/cm2) in vitro, an increased frequency of chromosome aberrations and SCE was observed. Normal levels of chromosome aberrations and SCE were found in lymphocytes of psoriasis patients after 3-30 weeks of PUVA treatment in vivo. A small but statistically significant increase in the SCE frequency was observed in the lymphocytes of psoriasis patients treated for 1-6 years with PUVA (mean 18.0 SCE/cell) as compared with before PUVA (mean 15.8, p less than 0.05). Skin fibroblasts of psoriasis patients analyzed 5 years after the start of PUVA treatment showed a normal number of SCE but a high fraction of filter-retained DNA in the alkaline elution assay, suggesting the presence of cross-linked DNA.
D002869:Chromosome Aberrations; D004247:DNA / Q000528:radiation effects*; D005347:Fibroblasts / Q000528:radiation effects; D006801:Humans; D008214:Lymphocytes / Q000528:radiation effects*; D011701:PUVA Therapy / Q000009:adverse effects*; D010778:Photochemotherapy / Q000009:adverse effects*; D011565:Psoriasis / Q000235:genetics / Q000473:pathology*; D012854:Sister Chromatid Exchange; D012867:Skin / Q000528:radiation effects*; D013997:Time Factors
D004247:DNA