Immunomodulation by ultraviolet light: clinical studies and biological effects.

The interest of immunologists in ultraviolet (UV) irradiation stems from observations made in vitro and in vivo. In vitro, UV irradiation inhibits mitogen and mixed lymphocyte culture (MLC) responses and in vivo, it can induce cutaneous anergy, apparently via suppressor cells and serum factors. At present much interest is focused on the possible use of UV irradiation to permit transfusion without allosensitization and transplantation without either rejection or graft-versus-host disease (GVHD). Here, Derwood Pamphilon and colleagues discuss the current uses and potential of UV irradiation in transfusion and transplantation and relate these to experimental evidence on its effects at the cellular level.