Increased surface expression of class I MHC molecules on immunogenic cells derived from the xenogenization of P815 mastocytoma cells with 8-methoxypsoralen and long-wavelength ultraviolet radiation.
In a previous study we demonstrated that the treatment of the highly tumorigenic cell line, P815, with 8-methoxypsoralen and long-wavelength ultraviolet radiation resulted in the production of several immunogenic clones (tum-). Mice inoculated with the tum- cells survived much longer than mice inoculated with the original tumorigenic cells (tum+). It was suggested that the increased survival of mice treated with the tum- clones arose as a result of an increased antigenicity derived from the phototreatment. In this report we show that the tum- cells have a greater density of class I MHC molecules on their surface (50-157% compared to P815). Class I MHC density on the cell surface is required to elicit targeted cytotoxic responses. These results can be considered in terms of human class I MHC assays which show that many human tumor cells have a reduced expression of class I MHC. Because other DNA damaging agents have also been shown to enhance class I expression, it is suggested that in addition to the cytotoxic effects of these agents, other pleiotropic effects must be considered. Photochemotherapy may phenotypically alter cells so that the enhanced expression of class I MHC molecules on the surface of phototreated cells may be associated with the clinical responses observed in cutaneous T cell lymphoma patients.
D000818:Animals; D002999:Clone Cells / Q000528:radiation effects; D005434:Flow Cytometry; D006183:H-2 Antigens / Q000528:radiation effects*; D012515:Mast-Cell Sarcoma / Q000188:drug therapy / Q000276:immunology*; D051379:Mice; D011701:PUVA Therapy; D014407:Tumor Cells, Cultured
D006183:H-2 Antigens