Stimulation of the respiratory burst and promotion of bacterial killing in human granulocytes by intravenous immunoglobulin preparations

We have examined the effect of two i.v. immunoglobulin preparations on the metabolic and functional activities of neutrophil granulocytes from the peripheral blood. Production of superoxide anion (O2-) by granulocytes was measured through superoxide dismutase inhibitable reduction of ferricytochrome C after incubation of cells for various times together with immunoglobulin (concentration ranging from 0.25 to 5.0 mg/ml). The results showed dose-dependent response of O2- production independent of the incubation time. Granulocytes containing ingested Staphylococcus aureus released a significantly (P less than 0.001) larger amount of O2- and killed a higher number (P less than 0.001) of viable bacteria in the presence of 5 mg/ml immunoglobulin than did cells incubated in the absence of extracellular i.v. immunoglobulin. These data raise the possibility that immunoglobulin concentrates for i.v. use may enhance the anti-bacterial activities of phagocytic cells through direct stimulation of the respiratory burst. Inflammatory reactions observed during i.v. immunoglobulin infusion in hypo- or agammaglobulinaemic patients may also be related to phagocytic cell activation.