EFFECT OF UVB 311 NM IRRADIATION ON NORMAL HUMAN SKIN

Ultraviolet radiation B (UVB) on the skin induces erythema, inflammati on and modifications of the immune system. These changes have been rep orted after excessive short-term or long-term exposure to broad spectr um UVB. In this study, we examined the effects of local repetitive UVB irradiation of 311 nm wavelength on the skin of seven young volunteer s. Skin biopsies were taken before and after UVB irradiation, and we i mmunohistochemically analyzed the expression of CD1a and HLA-DR antige ns of Langerhans cells (LC), the possible infiltration of dermis/epide rmis by CD11b macrophages, the modifications orthe induction of interc ellular adhesion molecule-1 (ICAM-1), E-selectin and vascular cell adh esion molecule-1 (VCAM-1) involved in the binding of leukocytes to the endothelial surface and the development of perivascular infiltrates o f LFA-1(+) mononuclear cells. We also determined the expression of sub stance P receptors (SPR) using biotinylated substance P (SPB). Exposur e of UVB 311 nm induced a drastic reduction of CD1a(+) cells and a mod erate increase of HLA-DR+ dendritic cells in the epidermis without inf iltration by CD11b macrophages. An increase of the binding oi SPB to u pper layer epidermal cells was noted in five of seven biopsies. In the dermis, vessel-associated ICAM-1 expression increased and an inductio n of E-selectin occurred on nearly 20 to 40% of endothelial cells, but VCAM-1 expression remained undetectable. The percentage of LFA-1(+) c ells did not change significantly after irradiation. These observation s may be compatible with a selective role of WE 311 nm on the skin imm une response.