LATE T-CELL DEFICIENCY IN VICTIMS OF THE CHERNOBYL RADIATION ACCIDENT- POSSIBLE MECHANISMS OF INDUCTION

T cell number, serum concentrations of thymic hormones and anti-epithe lial autoantibodies were studied in people affected at Chernobyl NPP. Group 1 took part in the clearing-up operation and had no clinical man ifestations of acute radiation sickness. Group 2 worked at the NPP dur ing the accident; they survived acute radiation sickness (degree I-II, subgroup 2a; degree III-IV, subgroup 2b). The total doses of external radiation were 0.1-0.5 Gy in group I, up to 4 Gy in subgroup 2a and u p to 9 Gy in subgroup 2b. Total T cell number, serum thymic activity a nd alpha1-thymosin concentration were decreased in all groups of affec ted persons. CD8+ cell number decreased only in group 1; CD4+ cell num ber in subgroup 2b. A decrease in thymic hormone level was most promin ent in subgroup 2b. The titres of anti-epithelial antibodies were incr eased in all groups of affected persons independently of radiation dos e. The titres were higher in patients with subnormal levels of alpha1- thymosin. It has been proposed that radiation alters the function of t hymic epithelial cells by direct action and/or through indirect mechan isms including participation of autoantibodies. The observed complex o f alterations is similar to that in the normal process of immunologica l ageing.