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Measurement of In Vivo Sunscreen Immune Protection Factors in Humans

1999; Wiley; Volume: 70; Issue: 6 Linguagem: Inglês

10.1111/j.1751-1097.1999.tb08301.x

1751-1097

Diona L. Damian, Ross StC. Barnetson, Gary M. Halliday,

Indoor Air Quality and Microbial Exposure

Abstract This study investigates the level of protection provided by sunscreens against solar‐simulated UV radiation‐induced immunosuppression in humans. The in vivo immune protection factors (IPF) of two broad‐spectrum sunscreens were determined by assessing their ability to prevent UV‐induced suppression of nickel contact hypersensitivity (CHS) in 15 nickel‐allergic volunteers. Each volunteer was irradiated on unprotected skin of the back with different doses of UV daily for 4 days. Multiples of these UV doses were concurrently delivered to sunscreen‐treated sites on the contralateral back. Nickel patches were then applied to both irradiated sites and adjacent, unirradiated control sites. Nickel‐induced erythema at each site was measured 72 h later with a reflectance spectrometer. Comparison of the nickel reactions of irradiated and unirradiated skin revealed linear UV dose–responses for immunosuppression in both unprotected and sunscreen‐treated skin. The minimum level of immunosuppression that can be reliably detected with this method is 20%. Therefore, the UV dose that reduces mean nickel CHS by 20% is the minimal immune suppression dose (MISD). Sunscreen IPF were determined by dividing the mean MISD of sunscreen‐treated skin by that of unprotected skin. The sunscreens, with sun protection factors of 9 and 24, had IPF of 6.5 and >25, respectively.