A UVB Wavelength Dependency for Local Suppression of Recall Immunity in Humans Demonstrates a Peak at 300nm

UVB radiation is a potent environmental carcinogen that not only causes mutations in the skin but also profoundly suppresses skin immune responses. Although this UVB-induced suppression of antitumor immunity has a key role in skin cancer development, the wavelengths within UVB causing greatest in vivo immunosuppression in humans are as yet unknown. We have identified a wavelength dependency for immunosuppression in humans across the UVB spectrum. We established linear dose–response curves for UV-induced local suppression of recall contact hypersensitivity responses at four wavelengths between 289 and 322nm and found peak immune suppressive effectiveness at 300nm and no detectable suppression at 322nm within a physiologically relevant dose range