Sunscreens have been used widely to prevent the photosensitive skin diseases, skin cancer, and skin aging. However, no sunscreen blocks all kinds of effects caused by ultraviolet light(UVL), and the effect of sunscreens on the impairment of immune function by UVL irradiation is controversial.

We try to evaluate the efficiency of sunscreens for blocking the depletion of LC induced by UVB irradiation.

The ATPase positive LCs were observed in the skin of hairless mice(Hr+/Kud) irradiated by UVB with or without topical application of sunscreens. Two commercially available sunscreens with respective SPF 8 and SPF 30 were applied to the dorsal trunk skin. The mice were irradiated with different increasing doses of UVB at a single time.

The ATPase positive LCs in the irradiated dorsal and ear skin were significantly de-creased in densities according to the dosage, and apparently revealed a loss of their dendrites, granulation, and clumping from a UVB dose of more than 60mJ/Cm². With both sun-screen treatment on the dorsal trunk before irradiation, the densities of LCs on the dorsal skin were significantly higher compared to the un-treated groups at all ranges of UVB doses in spite of a dose dependent decrease in their density. However there was no significant difference on their preventive effect between both sunscreens(SPF 8 and SPF 30) except at high UVB dos-es of more than 240mJ/Cm².

The LC depletion induced by UVB can be partially protected through the topical application of a sunscreen at a UVB dose dependent fashion. However SPF(sun protective factor) dose not appear to be a good indicator for evaluating sunscreens immunologically.