A high SPF sunscreen's effects on UVB-induced immunosuppression of DNCB contact hypersensitivity.

Several studies in mice of the protection afforded by sunscreens from UVB-induced suppression of contact hypersensitivity have yielded conflicting reports ranging from complete protection to no protection. Firstly, we sought to determine the effects of sunscreen and UVB on Langerhans cells; secondly we sought to determine whether the effect of preapplication of sunscreen with a sun protection factor of 30 could prevent local UVB-induced suppression of contact hypersensitivity to dinitrochlorobenzene in humans. In the first part of the study we compared a control group with a sunscreen plus UVB group and enumerated the number of Langerhans cells in each group. In the second part of the study we had four groups: a control group, a UVB group, a sunscreen group, and a sunscreen plus UVB group. Our results show that application of a sunscreen prior to UVB can prevent the decrease in number of Langerhans cells in an irradiated site. In the second part of the study, our results indicate that sunscreen, in itself, does not interfere with contact hypersensitivity, and that a high SPF sunscreen applied prior to UVB irradiation partially prevents suppression of contact hypersensitivity.