THE EFFECT OF VARIOUS SUNSCREEN AGENTS ON SKIN DAMAGE AND THE INDUCTION OF TUMOR SUSCEPTIBILITY IN MICE SUBJECTED TO ULTRAVIOLET-IRRADIATION

[摘要] Sunscreens containing various chemical UV absorbers, para-aminobenzoic acid (PABA), 2 PABA derivatives, benzophenone or a combination of these were topically applied to the backs of C3H/HeN mice prior to their being irradiated with UV light in the UVB range. This treatment prevented the pathological skin changes associated with UVB irradiation. Histological evaluation of skin biopsies from mice treated with the sunscreens and UVB irradiation showed little or no difference from normals in amount of hyperplasia, melanization or parakeratosis present.sbd.changes were observed in unprotected animals receiving UVB irradiation. Pretreatment with the sunscreens did not prevent the induction of tumor susceptibility as measured by the sustained growth of a UV-induced tumor which is immunologically rejected in normal syngeneic mice. This distinction between the effects of UVB irradiation leading to histological changes in the epidermis and those leading to the state of tumor susceptibility in mice was corroborated by the finding that epidermal hyperplasia induced by croton oil had no significant effects on the induction of tumor susceptibility. The induction of tumor susceptibility is not due to wavelengths of light < 320 nm since this effect was abrogated when the UVB radiation was filtered through glass. Possible mechanistic differences between the tumor susceptibility generated in UVB and photoprotected UVB irradiated animals were observed when an attempt was made to adoptively transfer the state of tumor susceptibility to normal animals. While it was readily transferable with splenic lymphoid cells from UVB irradiated animals, all attempts to transfer the tumor susceptibility from photoprotected animals have been unsuccessful.