Late Mortality in Midlethally Irradiated Mice Given Injections of Hematopoletic Cells From F₁ Hybrids

Summary

Bone marrow or spleen cells of A, CBA, or (CBA × A)F₁ mice were injected into midlethally (550 R) and lethally (900 R) irradiated CBA mice. Unlike mice not given injections, midlethally irradiated CBA mice given injections of A or (CBA × A)F₁ hybrid cells had a characteristic increase in mortality between 22 and 90 days after irradiation. The gross and microscopic findings, especially in the lymphoid organs, were similar to those in secondary disease, although a graft-versus-host reaction could be ruled out when F₁ cells were injected. Lymphoid atrophy was invariably observed in the dead mice, just as in secondary disease, and is believed to be the factor responsible for death. It is suggested that “allergic death” of reacting cells is one of the mechanisms which leads to the lymphoid tissue atrophy.