Interstitial murine cytomegalovirus pneumonia after irradiation: characterization of cells that limit viral replication during established infection of the lungs.

Interstitial pneumonia associated with viral replication in lung tissue was observed after cytomegalovirus infection of total-body gamma-irradiated mice, whereas in noncompromised hosts the lungs were not affected and virus multiplication was restricted to the salivary glands. The radiation damage could either predispose normally nonpermissive cell types for productive infection or abrogate an immune control of the tissue manifestation of infection by elimination of lymphocytes. Adoptive transfer of lymphoid cells into irradiated, infected recipients supported the second alternative. Even when infection was established in the lungs, as manifested by the presence of infected lung tissue cells in the alveolar septa, an antiviral effect could be assigned to the Lyt-2+, L3T4- subset of T lymphocytes specifically sensitized in the immunocompetent donor. These cells did not require in vitro propagation to perform effector cell functions in vivo and were operative under physiological conditions in comparatively low numbers. Hence, there is reason to assume that T lymphocytes are responsible for the tissue distribution of cytomegalovirus replication during infection.