THE BEHAVIOR IN TRANSPLANT OF LYMPHOCYTIC NEOPLASMS ARISING FROM PARENTAL THYMIC GRAFTS IN IRRADIATED, THYMECTOMIZED HYBRID MICE

Abstract

Thymectomy prevents the development of lymphocytic neoplasms in (C57BL X A)F1 hybrid mice which have received a course of fractionated X-radiation. Twenty of 32 irradiated, nonthymectomized (C57BL X A)F1 hybrids developed lymphocytic neoplasms. The presence of thymic grafts obtained from 1-12-day-old C57BL donors partially restores the ability of the irradiated host to develop lymphocytic neoplasms. The site of origin of the lymphocytic neoplasms in thymectomized, irradiated, thymic-grafter mice is the grafted thymus. The progenitor cells of the lymphocytic neoplasms arising in the thymic grafts studied in this experiment were contributed from either the (C57BL X A)F1 host or, in a smaller number of cases, from the nonirradiated C57BL graft, as determined by the histocompatibility character of the resulting neoplasm. A discussion is given of this experimental approach to the time and site of origin of the leukemic cell and the mechanisms involved in leukemogenesis.