Immune protection factors of chemical sunscreens measured in the local contact hypersensitivity model in humans.
We conducted a randomized trial designed to calculate human in vivo immune protection factors of two sunscreen preparations in a model of ultraviolet-induced local suppression of the induction of contact hypersensitivity to 2,4-dinitrochlorobenzene. Seventy-five male subjects were exposed in a multistage study to multiples of their individual minimal erythema dose of solar-simulated ultraviolet radiation with or without protection by an ultraviolet B sunscreen (sun protection factor 5.2) or a broad-spectrum ultraviolet A + B sunscreen (sun protection factor 6.2). After 24 h subjects were sensitized with 50 microL of 0.0625% 2,4-dinitrochlorobenzene on a nonirradiated or ultraviolet-irradiated field on the buttock that was unprotected or protected by sunscreen. Three weeks after sensitization the subjects were challenged with varying concentrations of 2,4-dinitrochlorobenzene on their upper inner arm, and the contact hypersensitivity response was determined at 48 and 72 h based on a semiquantitative clinical score, contact hypersensitivity lesion diameters, and dermal skin edema measurement by 20 MHz ultrasound. The 50% immunosuppressive dose ranged from 0.63 to 0.79 minimal erythema dose, depending on the endpoint parameter. Both sunscreens offered significant immunoprotection (p = 0.014-0.002) and their immune protection factor ranged from 4.5 to 5.8 (ultraviolet B sunscreen) and from 7.7 to 11 (ultraviolet A + B sunscreen). The immune protection factor of the ultraviolet B sunscreen was similar to the sun protection factor (5.2), whereas the sunscreen with broad-spectrum ultraviolet A + B protection exhibited better immunoprotective capacity than predicted from the sun protection factor.
Wolf
Peter
P
Department of Dermatology, Karl-Franzens-University, Graz, Austria. peter.wolf@kfunigraz.ac.at
Hoffmann
Christine
C
Quehenberger
Franz
F
Grinschgl
Stephan
S
Kerl
Helmut
H
D000328:Adult; D003877:Dermatitis, Contact / Q000276:immunology*; D005260:Female; D006801:Humans; D007108:Immune Tolerance / Q000187:drug effects / Q000528:radiation effects*; D008297:Male; D008875:Middle Aged; D009381:Neoplasms, Radiation-Induced / Q000209:etiology; D012878:Skin Neoplasms / Q000209:etiology; D013473:Sunscreening Agents / Q000494:pharmacology*; D014466:Ultraviolet Rays / Q000009:adverse effects*
D013473:Sunscreening Agents