Depression of humoral responses by murine cytomegalovirus infection

The ability of mice infected with murine cytomegalovirus (MCMV) to respond to unrelated antigens in vivo was studied in genetically sensitive BALB/c and genetically resistant CBA mice. Suppressed humoral responses were observed following intraperitoneal or intravenous antigen challenge a few days after infection. IgG production was depressed more frequently than IgM. The suppression was correlated with splenic atrophy and hyporesponsiveness of the residual spleen cells in vitro. The peritoneal macrophage response to intraperitoneal adjuvant challenge was also modified by the infection. Subcutaneous antigenic challenge elicited normal or elevated humoral and delayed-type hypersensitivity responses, during which peripheral lymph nodes were consistently expanded. Antigen administered intraperitoneally without adjuvant on the day of infection also evoked elevated humoral responses. This correlates with the host's ability to respond to MCMV itself, possibly via primed cells seeded to the lymph nodes before the spleen was damaged by the infection.