Human cytomegalovirus neutralizing antibody response in Japanese children with bone marrow transplantation

Thirty-two children with bone marrow transplantation (BMT) received intravenous injections of gammaglobulin (IVIG) with a high titer of neutralizing (NT) antibody against human cytomegalovirus (HCMV) (200 mg/kg/week) from 1 week before to 4 months after transplantation. NT antibody titers before BMT and the highest levels in serial determinations conducted after BMT were compared for each patient. They were classified into three groups according to the antibody response: primary HCMV infection as group I, endogenous reactivation or external reinfection as group II, and indeterminable cases as group III. Two (6.3%) out of 32 patients examined had BMT-associated primary HCMV infections, but did not show any clinical symptoms. Significant changes in clinical parameters were also lacking in all the other 30 patients, independent of whether they shed viruses into the urine, or demonstrated on antibody boost. It was concluded from the group variation that the antibody response was indeed due to the engraftment of BMT, rather than to a direct effect of treatment with IVIG. Our results further indicate that passive immunization with HCMV antibody does not prevent infection, but confers some protection against symptomatic disease.