[Immune reaction in monkeys to single and fractionated low-dose gamma-irradiation]

A study was made of total and local immunity of two groups of Papio hamadryads subjected to single and ten-fold external gamma-irradiation at a cumulative dose of 5 cGy. It has been shown that with equal dosages changes in the relative and absolute number of lymphocytes in the peripheral blood, the number of circulating T-cells and their functional activity are more pronounced in animals subjected to fractionated irradiation. Both groups exhibited similar disturbances in the functional activity of antibody-dependent killers and in local immunity of stomatopharynx. Analysis of the immunological data and the results of hydrocortisone content determinations in blood serum of exposed animals has demonstrated the presence of both direct effect of low-level radiation on the immune system and indirect effect that is particularly pronounced in case of multifraction long-term irradiation.