Distribution of lymphocyte subsets following radiation therapy directed to different body regions

Local radiation therapy may severely deplete the recirculating pool of lymphocytes as manifested by a reduction of blood lymphocyte counts. There is considerable controversy, however, concerning the changes of the distributions of subsets of blood lymphocytes during the acute and late phases after irradiation. This report provides evidence that radiation therapy directed to different anatomic sites may change the distribution of subsets of blood lymphocytes in different ways. For instance, during the acute phase after radiation therapy for breast cancer there is a more extensive reduction of the proportion of lymphocytes with receptors for C3 than that of lymphocytes with receptors for sheep erythrocytes (characteristics of B- and T-cells respectively). Such a difference, however, was not observed in groups of patients receiving pelvic irradiation. The controversy in the literature concerning the distribution of lymphocyte subsets after irradiation may thus in part be due to the fact that the patients examined have received radiation therapy to different body regions.