Immune deficiency influences juvenile social behavior and maternal behavior

Mice with severe combined immunodeficiency (SCID) lack functional T and B lymphocytes, and have impaired cognitive abilities. We assessed social behaviors in male SCID and C57BL/6 (B6) juvenile mice. In a social preference task, SCID mice spent more time than B6 mice investigating a novel adult male mouse. In a social recognition task, SCID mice habituated to a novel ovariectomized mouse, but failed to show dishabituation when presented with an unfamiliar individual. We hypothesized that partial immune restoration could normalize behaviors. SCID pups (postnatal Day 7) received either saline or splenocytes from normal donors. Splenocyte-replaced SCID mice spent less time interacting with a novel mouse than saline-injected SCID or B6 control mice. Again, control SCID mice failed to dishabituate to a novel mouse, but splenocyte-replaced SCID mice showed dishabituation. In both of these studies, B6 and SCID pairs were used to produce offspring that remained with their dams until weaning. There are no studies of maternal behavior in SCID dams; therefore to investigate the potential role for this factor, we quantified maternal behavior in SCID and B6 dams; several significant differences were found. To control for differences in maternal care, we mated heterozygous SCIDs to produce offspring. These homozygous SCID and wild-type offspring reared by dams of the same genotypes displayed similar responses to a novel mouse; however, in the social recognition task, SCID males did not display dishabituation to a novel mouse. Taken together, our data indicate that Gene × Environment interactions influence social interactions in immune deficient mice.