Importance of cytotoxic lymphocytes during cytomegalovirus infection in renal transplant recipients

Thirty renal transplant recipients were studied prospectively to evaluate the relationship of cytomegalovirus-specific cytotoxic lymphocyte responses to clinical outcome during cytomegalovirus infection. Cytomegalovirus infection developed in 20 patients; of these 20, 14 had cytomegalovirus-specific cytotoxic lymphocyte responses whereas six did not. Clinical findings (fever, leukopenia, thrombocytopenia, or elevations in serum transaminase levels) were significantly more frequent among patients without responses than among patients with responses (p < 0.001), and prolonged viremia and complications of infection including superinfection, interstitial pneumonitis, pancreatitis, and death occurred exclusively among patients without responses. Acute allograft dysfunction during infection was experienced by four patients without responses but by only one patient with response (p = 0.02), indicating that the virus-specific cytotoxic response did not result in a renal immunopathologic condition, and may have protected against virus-induced injury to the graft. In seven of nine patients with responses who shed virus, cytotoxic responses occurred within one week of detection of activation of virus shedding. Absence of cytotoxic responses correlated with prior high-dose, intravenous methylprednisolone treatment, and apparently resulted from inhibition of cytotoxic T cell precursors. Immunosuppressive treatment to inhibit graft rejection should be minimized, and methods should be developed that do not inhibit cytomegalovirus-specific cytotoxic T cell responses.