Computer-assisted morphometric analysis of radiation injury in murine lymphocytes

Groups of mice were killed 1, 3, 7 and 15 days after whole body exposure to 0, 5, 50 or 500 rads of irradiation. Lymphocytes were harvested from the peripheral blood and spleen for total and differential leukocyte counts, for determination of the absolute numbers of thymic-dependent (T) and bone marrow-dependent (B) cells and the in vitro responsiveness to phytohemagglutinin (PHA), concanavalin A (Con A) and lipopolysaccharide (LPS) mitogens and for computer-assisted morphometric analysis (CAMA) of Feulgen-stained nuclei. Alterations in functional activity and morphometric composition showed the same trends with respect to radiation injury, with maximum effects observed three days after exposure. The spleen contained a greater proportion of altered cells than did the peripheral blood. Comparison of the results with similar data obtained from lymphocytes irradiated in vitro showed that the same micromorphometric descriptors serve to distinguish irradiated from control cells in both cases.