We investigated the capacity of three
sunscreen compounds to protect mice from the inflammatory and immunosuppressive effects of ultraviolet radiation (UVR). The
sunscreen preparations contained 7.5%
2-ethylhexyl-p-methoxycinnamate, 8% octyl-N-dimethyl-
p-aminobenzoate, or 6%
benzophenone-3 in an oil-in-water
emulsion. Skin swelling was used as the measure of their effect on UVR-induced
inflammation, and immunosuppression was assessed by contact sensitization with 2,4-dinitrofluorobenzene applied to UV-irradiated skin (local suppression) or a distant site (systemic suppression). The
sunscreens were applied to the shaved dorsal skin of C3H mice, which were then given a single dose of UVR ranging from 2 to 32 kJ/m2 within the UVB (280-320 nm) region. All three
sunscreens gave complete protection against local suppression of
contact hypersensitivity caused by a dose of 2 kJ/m2 UVB. They also protected against both
inflammation and systemic immunosuppression caused by UVR; however, protection was highly dependent on the UVR dose. Furthermore, the
sunscreens were less effective in protecting against systemic immunosuppression than against
inflammation. These results indicate that immunosuppression is less sensitive to the protective effects of the
sunscreens than
inflammation and that protection against UVR-induced
inflammation does not necessarily imply prevention of immunologic alterations. In addition, these studies suggest that UVR-induced immunosuppression and
inflammation may involve different mechanisms.