Effect of UV radiation on interferon, immunoglobulins and complement components in serum from healthy individuals

An infectivity inhibition micro-method was used to detect interferon (IFN) in sera from 20 healthy individuals before and after UVA irradiation, and in sera from 22 healthy individuals before and after UVB irradiation. The serum levels of IFN, immunoglobulins (Ig) and complement components (C) were examined before irradiation, after 10 and 20 exposures, and 4 weeks after irradiation. The median serum IFN level in both the UVA and the UVB group increased significantly during irradiation, most markedly during the 10 first exposures. Four weeks after irradiation the median IFN level was reduced in both groups, but had not reached the pre-irradiation levels. The IFN level was unchanged or reduced in 2 individuals in the UVA group and in 5 individuals in the UVB group. Characterization experiments indicated the presence of both acid-stable and acid-labile IFN-alpha and IFN-gamma. The mean serum IgG concentration was significantly reduced 4 weeks after UVA irradiation, whereas IgA, IgM, C3 and C4 were not affected. The mean serum concentrations of IgG and C4 were significantly reduced 4 weeks after UVB irradiation, whereas the mean concentrations of IgM and C3 were significantly increased. The concentration of IgA was not affected.