Abrogation by Injected Mouse Blood of Protective Effect of Foreign Bone Marrow in Lethally X-Irradiated Mice

Abstract

IT was observed recently¹ that intraperitoneal injection of whole blood or of leukocytes from parental strain mice (A or C57 strains) into sub-lethally X-irradiated (L × A)F ₁ hydrid mice results in marked lymphoid atrophy and delayed deaths in these recipients. Similar effects have been observed after administration of lymphoid tissue cells of the parental strain (spleen, lymph node) under the same conditions². These results suggested that peripheral blood contains cellular elements which are capable of immunological reactivity. According to this view, the recipient mice succumb as a consequence of a donor-to-host homograft reaction, initiated by the injected blood cells or their progeny. Furthermore, earlier work³ had shown that injection of isologous lymphoid tissue cells (from spleen or thymus) a few hours after lethal X-irradiation of mice elicits the early rejection of rat marrow transplants, whereas such grafts ordinarily ‘take’ in lethally X-irradiated mice. (Isologous—from the same inbred strain ; homologous—from the same species, but different genotype ; heterologous—from a different species.) It was, therefore, of interest both theoretically and from a practical point of view, to determine whether the administration of normal whole blood would similarly cause rejection of foreign bone marrow transplants in X-irradiated mice.