In vivo effect of UV-B on lymphocyte function.

Whole-body exposure of normal subjects to erythemogenic doses of UV-B radiation results in a decrease in the proportion of circulating E-rosette-forming lymphocytes, an increase in the proportion of null cells and a decreased incorporation of tritiated thymidine into DNA of lymphocytes following stimulation by phytohaemagglutinin (PHA). These alterations are dose-dependent, appear soon after exposure, reach a maximum after 8-12 h, and are reversed by 48-72 h post exposure.