The effect of a sunscreen containing para-aminobenzoic acid on the systemic immunologic alterations induced in mice by exposure to UVB radiation.

Application of a sunscreen containing para-aminobenzoic acid partially abrogated certain of the systemic immunologic alterations produced in mice by exposure to UVB (280-320 nm) radiation from sunlamp bulbs. The sunscreen reduced the degree of UVB-induced suppression of contact hypersensitivity to a chemical applied subsequently to nonirradiated skin. In addition, it reduced the frequency with which mice became susceptible to the growth of a highly antigenic, syngeneic, UVB-induced tumor following chronic treatment with UVB radiation, but this effect was not statistically significant. The tumor-susceptible state was transferred from animals treated with sunscreen and UVB radiation to lethally x-irradiated mice by injection of spleen cells. The gross morphology of the skin of mice treated with sunscreen and UVB radiation was normal but the histologic changes induced by UVB irradiation in skin were only partially abrogated by the sunscreen.