Cellular aspects of radiation leukemogenesis in C57 BL/Ka mice: alterations to thymic microenvironment and lymphopoiesis.

After a leukemogenic split dose course of irradiation, thymic nurse cells (TNCs) disappear. We have correlated this with the loss of an epithelial cell surface antigen (recognized by monoclonal antibody ER-TR3 and tentatively identified as Ia). In addition, epithelial cells have lost their capacity to interact with fetal thymocytes in vitro. Marrow grafting early after irradiation, that prevents the development of lymphomas, restores thymic nurse cells and thymocyte population. Such reconstitution and lymphoma prevention were not observed when marrow grafting was performed later (1 month after irradiation) during the preleukemic period.