The UV waveband dependencies in mice differ for the suppression of contacthypersensitivity, delayed-type hypersensitivity and cis-urocanic acid formation

Solar radiation contains ultraviolet B (280-315 nm) and ultraviolet A (ultr aviolet All, 315-340 nm; ultraviolet Al, 340-400 nm) wavebands, Ultraviolet B is known to suppress certain aspects of cell mediated immunity. Using th ree ultraviolet lamps (the broadband ultraviolet B TL-12, the narrow-band u ltraviolet B TL-01 and an ultraviolet Al source), we investigated the dose and waveband dependencies for the suppression of contact hypersensitivity t o oxazolone and delayed-type hypersensitivity to herpes simplex virus, plus the formation of cis-urocanic acid in C3H/HeN mice. A single exposure of 1 500 J/m(2) TL-12 or 10,000 J/m(2) TL-01 or 500,000 J/m(2) ultraviolet Al co rresponded to 1 minimum erythema dose in this mouse strain. The percentage of cis-urocanic acid of the total urocanic acid rose from a background leve l of 1.7% to 40% with 1000 J/m(2) TL-12 or 10,000 J/m(2) TL-01, but only 17 % cis-urocanic acid was obtained with 500,000 J/m(2) ultraviolet Al, The co ntact hypersensitivity response was significantly suppressed after a minimu m dose of 5000 J/m(2) TL-12 or 50,000 J/m2 TL-01 or 500,000 J/m2 ultraviole t Al, The delayed-type hypersensitivity response was suppressed by a minimu m dose of 100 J/m(2) TL-12 or 10,000 J/m2 TL-01 or 1000 J/m(2) ultraviolet AI, So, whereas a low dose of ultraviolet Al reduced the delayed-type hyper sensitivity response, a 500-fold higher dose was required to suppress conta ct hypersensitivity. There was no correlation between the suppression of th ese responses and the concentration of cis-urocanic acid in the skin. Thus different mediators may modulate the various immune responses affected by u ltraviolet exposure, depending on the wavelength of the radiation.