Murine cytomegalovirus-induced immunosuppression.

The mechanism of murine cytomegalovirus-induced immunosuppression was investigated by examining the roles played by lymphocytes and adherent cells derived from spleens of infected SWR/J mice. As few as 100 infected cells per spleen were correlated with complete abrogation of mitogen responses at 4 and 5 days after infection. In a series of cell mixing experiments it was shown that the deficiency in infected spleens was due partly to the adherent cells, which apparently secreted an immunosuppressive factor, and partly to the infected lymphocytes, which upon exposure to this factor could no longer respond to concanavalin A presented to them by normal adherent cells.