Computer analysis of defined populations of lymphocytes irradiated in vitro. III. Evaluation of human T and B cells of peripheral blood origin.

The radiosensitivities of lymphocytes of peripheral blood origin obtained from two healthy 45 year old male donors were studied simultaneously at yearly intervals over a three year period. Hypaque-Ficoll purified cells were exposed in vitro to 0, 5, 50, and 500 rads and then evaluated serially for viability of T and B cells, responsiveness to PHA and Con A, and morphologic evidence of injury as documented by standard light microscopy and computer assisted morphometric analysis. The results showed that T cells in both subjects were less radiosensitive than B cells. Differences between the two subjects also existed in the radiosensitivity of these two subpopulations of lymphocytes, differences that remained constant over the three years period of observation. The differences correlated with similar discrepancies in mitogenic responsiveness and are thought to relate to variations in the relative proportions of subpopulations of T and B cells. In the mouse, T and B cell subpopulations differ in radiosensitivity. The data reported herein are consistent with a similar situation in man.