Effect of Immunosuppression on Humoral and Cell-Mediated Immunity to Murine Cytomegalovirus

C57B1/6 mice were immunosuppressed with antilymphocyte globulin and prednisolone around the time of infection with cytomegalovirus (CMV) or from 18 to 30 days after infection. Mice immunosuppressed around the time of CMV infection developed humoral immunity (HI) but not cell-mediated immunity to CMV. The ability of spleen cells to transform to nonspecific mitogens was also depressed in immunosuppressed mice. If mice were immunosuppressed from 18 to 30 days after infection, a time they are known to have CMI to CMV, the CMI disappeared and remained low for the duration of the study (67 days after infection). However, HI was not affected. Transformation of spleen cells to nonspecific mitogens similarly remained low. These studies demonstrate that immunosuppression can abrogate CMI but not HI to CMV.