The influence of therapeutic irradiation of blood and peripheral lymph lymphocytes

This paper reviews the changes of blood and peripheral lymph lymphocytes induced by therapeutic irradiation as given for a variety of lymphoid and nonlymphoid neoplastic diseases. The irradiation brings about an abrupt reduction of the numbers of blood B and T lymphocytes. The number of lymphocytes seems to be restored within a few months after irradiation, while at least 3-5 years appear to pass before the number of blood T lymphocytes is restored. The pattern of recovery seems to be the same whether the thymus has been included in the fields of irradiation or not. In the adult organism, considerable differences apparently exist between the capacities for reproduction of B and T lymphocytes. The number of lymphocytes in peripheral lymph is also much reduced in the irradiated patient and remains so for a long period. This is compatible with the concept that migration from blood to peripheral lymph is a feature quite specific for T lymphocytes. These results are discussed in relation to the immune defense against infection and autologous tumor, and also in relation to the influence of radiotherapy on the immune defect in Hodgkin's disease.