OCCUPATIONAL EXPOSURE AND ITS EFFECT ON SOME IMMUNE PARAMETERS

Some immunological parameters were investigated in a group of workers exposed to external radiation (1.4 to 9.8 mSv) and inhalation of triti um (comm. eff. dose equiv. 1.2 to 2.8 mSv). The present investigations indicate the differential radiosensitivity of lymphocytic subsets: CD 8 positive suppressor T cells were found to be the most sensitive subp opulation in the peripheral blood of radiation exposed workers. CD4/CD 8 ratios were increased mainly due to an increase in absolute numbers of CD4 positive helper T cells indicating a selective cell renewal aft er irradiation. Results obtained after phytohaemugglutinin stimulation of lymphocytes showed individual variation, though there seems to be a trend towards an inverse correlation between absolute T cell numbers in peripheral blood and the number of S phases observed after stimula tion, low T cell numbers leading to a high rate of stimulation. The ca lculation of the committed effective dose equivalents show that radiat ion protection against internal tritium contamination in power plants should not be neglected.