Primary CMV infection is associated with a vigorous T lymphocyte response; activated CD8+ T cells predominate among atypical lymphocytes.

• Latent infection occurs in multiple cell types and various organs. Chronic antigen stimulation in the presence of immunosuppression (e.g., in the transplantation setting) and certain immunosuppressive agents (e.g., antithymocyte globulin) promote CMV reactivation.
• CMV disease increases the risk of infection with opportunistic pathogens by depressing T lymphocyte responsiveness.