Measurement of ultraviolet radiation-induced suppression of recall contact and delayed-type hypersensitivity in humans.

This article describes methodology used for assessment of ultraviolet radiation-induced suppression of recall responses in humans. Nickel allergy is common in the general population and patch testing of nickel-allergic volunteers provides a convenient model of contact hypersensitivity. Similarly, Mantoux-positive volunteers, recruited from within hospital staff, are used as a model for delayed-type hypersensitivity. Use of secondary rather than primary immune responses allows placement of multiple test sites on each volunteer. Further, each volunteer acts as his or her own unirradiated control. This enables UV immunosuppression to be studied with relatively few human volunteers, and makes determination of UV immunosuppression dose responses feasible in human subjects. The method can also be used for assessment of the level of immune protection afforded by agents such as sunscreens or biologically active substances.