Immunosuppressive agents and cytomegalovirus infection

Cytomegalovirus (CMV) infection is the major infectious complication observed after organ transplantation. As rejection episodes always occur in allograft-transplanted recipients, various kinds of immunosuppressive agents are used to control such rejection episodes. Among the commonly used immunosuppressive agents, anti-pan-T cell polyclonal and monoclonal antibody are known to increase the risk of viral infections. New immunological techniques have recently been developed to measure CMV-specific CD4 and CD8 cells by flow cytometry. Using the techniques, high frequencies of specific CD4 and CD8 T cells have been shown to be required to survey the CMV (re)activation in the persistent/latent phase of CMV infection. An excessive T cell depletion by OKT3 would deplete such surveying T cells, thus resulting in the occurrence of CMV-associated diseases.