A SINGLE EXPOSURE OF SOLAR SIMULATED RADIATION SUPPRESSES CONTACT HYPERSENSITIVITY RESPONSES BOTH LOCALLY AND SYSTEMICALLY IN HUMANS - QUANTITATIVE STUDIES WITH HIGH-FREQUENCY ULTRASOUND

Ultraviolet radiation (UVR)-induced suppression of cutaneous cell-medi ated immunity plays an important role in the development of photocarci nogenesis in the mouse and a similar role is suspected in humans. Cell -mediated immunity is readily tested in vivo by measuring the contact hypersensitivity (CHS) response to topically applied haptens. CHS in h umans is usually determined clinically, with a subjective scoring syst em. However, these subjective scores cannot be statistically analysed. This paper compares four methods currently used to quantify CHS elici tation responses in humans. The data show that ultrasound images provi de the most accurate and reproducible measurements of the clinically o bserved CHS response. We also demonstrate that assessment of the prima ry allergic response is a useful indicator of the magnitude of the eli citation response and can be used to avoid severe CHS reactions in vol unteers. There are few human studies investigating the effects of sola r simulated radiation (SSR) exposure on immunosuppression. In this stu dy we demonstrate SSR is highly immunosuppressive in all subjects test ed. Irradiating a small area of skin with a single exposure to 3MEDs o f SSR completely suppressed CHS both locally (12/12 volunteers) and sy stemically (10/12 volunteers). Our data do not support a role for a ge netic susceptibility to UVR-induced immunosuppression in humans. (C) 1 998 Elsevier Science S.A. All rights reserved.