Prevention of late deaths in X-irradiated mice by injected hematopoietic cells from homologous newborn donors

Abstract

Previous studies have shown that the injection of spleen cells from normal adult parental strain (A-strain) mice into sublethally x-irradiated (500 r) F₁ hybrid mice ((LxA)F₁), elicits delayed deaths in 100% of the animals. This lethal effect is elicited, as shown here, also by spleen cells from adult L-strain mice, but not by spleen cells derived from newborn (1–2-day-old) parental strain mice. Following supralethal whole-body x-irradiation (870 r) of LAF mice, the injection of cells from spleen or liver of newborn A-strain mice afforded up to 100% protection against death by 30 days postirradiation; no late ‘homologous deaths’ were seen in the mice which received spleen cells from the newborn A-mice, in contrast with that observed when hematopoietic cells from adult A-mice are injected. The data imply that spleen cells from newborn mice are immunologically nonreactive, and lend further support to the hypothesis that late homologous deaths (in the context employed here) results primarily from an immunological reaction of the injected cells against the host.