Radiation-induced immunity changes and their potential role in the development of late radiation effects in humans

As a result of medical examinations an increased activity of mainly T-link immunity and natural cytoxicity was registered in healthy subjects and patients with obligate types of precancer of respiratory organs and female sex organs among the South Urals residents exposed to chronic combined external γ- and internal (mostly due to 90Sr) radiation. Individuals with precancerosis were found to have an increased fagocytic activity of monocytes and neutrophils which, nevertheless, retain their oxidation-reduction function. The frequency of immunologic disorders (predominantly infectious syndrome) was significantly higher among exposed tumor-carriers. Genetically-determined immunity changes were manifested by immunologic disbalance and were detected among HLA-antigen carriers of B locus. A certain increase in the frequency of TCR mutant lymphocytes with dose to RBM was noted. The results of the study are suggestive of an important role played by radiation-induced inhibition of anti-tumor immunity in the development of long-term, primarily carcinogenic, exposure effects.