Cytomegalovirus-induced immune suppression. II. Cell-mediated immunity.

Murine cytomegalovirus (CMV) causes depression of cell-mediated immunity. Skin graft survival is significantly prolonged across the strong H-2 and weak H-Y histocompatibility barriers in mice previously infected with CMV. Maximum prolongation of skin graft survival across the H-2 barrier occurred in mice infected on the day of grafting and survival was significantly prolonged in mice infected up to 5 days before grafting. CMV also inhibited uptake of tritiated thymidine by spleen cells in response to pytohaemagglutinin (PHA) or in mixed lymphocyte culture. Inhibition of responsiveness to PHA occurred for up to 26 days after infection. Uptake of tritiated thymidine was significantly elevated over controls 5 days after infection but not after this time.