Rapid clearance of cytomegalovirus-specific IgG after repeated intravenous infusions of human immunoglobulin into allogeneic bone marrow transplant recipients.

We studied the kinetics of the disappearance of CMV-specific IgG from the serum of 18 allogeneic bone marrow transplant recipients who were receiving repeated intravenous infusions of immunoglobulin. Peak serum titers occurred 24-48 hr after infusion. The mean half-life of IgG to CMV varied from 30 to 70 hr. Additional studies showed that this unexpectedly short half-life was not specific for either the preparation used or the type of patient studied. Repeated treatment did not prevent patients from developing CMV infections (incidence, 50%); however, none of the patients developed CMV interstitial pneumonitis. Treatment had to be discontinued for one patient because of a serum sickness-like syndrome. Our results suggest that rational, time-sequential passive immunization regimens should be developed.