Virus-specific IgG and IgM antibodies in normal and immunocompromised subjects infected with cytomegalovirus

Levels of IgG and IgM antibodies t human cytomegalovirus (CMV) were measured using a solid-phase radioimmunoassay. Individuals positive by complement-fixation test consistently had detectable IgG titers by radioimmunoassay, but no quantitative relationship was apparent. An elevated IgM titer was considered specific for CMV infection because sera from individuals with other herpesvirus infections did not cross-react. In patients with mononucleosis, elevated titers of IgM antibody to CMV correlated (P less than 0.001) with active infection and were highest during viremia. Titers of IgG antibody to CMV during and after symptomatic infection were similar to those of asymptomatic positive individuals. Increases in CMV-specific IGM were observed in both primary and reactivated infections in cardiac transplant recipients. In a small group of cardiac transplant recipients with recurrent symptomatic disease, IgM titers were low at the time of viruria and did not increase with CMV tissue involvement, a result which suggests that quantitative deficiencies in IgM may be related to the severity of CMV infections.