Effect on neutrophil kinetics and serum opsonic capacity of intravenous administration of immune globulin to neonates with clinical signs of early-onset sepsis.

This study was designed to test the hypothesis that administration of immune globulin to human neonates with early-onset bacterial sepsis would (1) facilitate neutrophil egress from the marrow, (2) improve serum opsonic capacity, and (3) facilitate recovery from the infectious illness. Twenty-two newborn infants with clinical signs of early-onset sepsis were given an intravenous infusion of either 750 mg of immune globulin (IVIG) per kilogram of body weight or the same volume of a vehicle control (albumin). All 22 infants survived, but significant hematologic, immunologic, and respiratory differences were observed after the IVIG and not after the control infusion. Eleven of the patients had neutropenia; 24 hours after the infusions, the neutropenia had resolved in all six IVIG recipients but persisted in all five control recipients (p less than 0.001). Ten patients had I/T neutrophil ratios (a measure of immature neutrophils to total neutrophils on the leukocyte differential count) of less than 0.2. One hour after completion of the infusions, all five IVIG recipients had elevated I/T ratios (mean +/- SEM:0.10 +/- 0.05 before vs 0.43 +/- 0.03 after infusion; p less than 0.001), suggesting a prompt release of neutrophils from the marrow neutrophil storage pool into the circulation; no increase in the I/T ratio was observed in the control recipients. Six hours after the IVIG infusions, the ratio of arterial oxygen tension to fraction of inspired oxygen increased; no increase was observed after control infusions. Serum concentrations of IgG, IgG1, IgG2, IgG3, IgG4, and total hemolytic complement and the capacity of serum to support opsonophagocytosis of type II and type III group B streptococci increased markedly in the IVIG recipients but not in the control subjects. We conclude that administration of 750 mg IVIG per kilogram to neonates with clinical signs of early-onset sepsis was associated with immunologic, hematologic, and physiologic improvement.