Influence of IgG, F(ab')2 and IgM on the phagocytic and bactericidal activities of human neutrophil granulocytes

The phagocytosis and intracellular killing of Staphylococcus aureus by humans granulocytes in the presence of immunoglobulin preparations have been examined. Isolated IgG from pooled human serum induced phagocytosis and intracellular killing of bacteria. F(ab')2 fragments had no significant effect, indicating that the Fc piece of the IgG molecule is of importance not only for the phagocytosis but also for the intracellular killing of bacteria. Isolated IgM stimulated the phagocytosis to a minor extent, with no enhancement of the bactericidal activity.