title: Measurement of in vivo sunscreen immune protection factors in humans.
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.
authors.affiliation: Department of Medicine (Dermatology), University of Sydney at Royal Prince Alfred Hospital, Australia.
authors.forename: D L
authors.initials: DL
authors.lastname: Damian
authors.forename: R S
authors.initials: RS
authors.lastname: Barnetson
authors.forename: G M
authors.initials: GM
authors.lastname: Halliday
mesh_terms: D000328:Adult; D003877:Dermatitis, Contact / Q000209:etiology / Q000276:immunology / Q000517:prevention & control*; D004306:Dose-Response Relationship, Immunologic; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008875:Middle Aged; D009532:Nickel / Q000009:adverse effects / Q000276:immunology; D012867:Skin / Q000187:drug effects* / Q000276:immunology*; D013473:Sunscreening Agents / Q000627:therapeutic use*; D014466:Ultraviolet Rays / Q000009:adverse effects
chemical_list: D013473:Sunscreening Agents; D009532:Nickel