The effect of IgG, F(ab')2 and serum on the glucose metabolism in human leucocytes

The glucose metabolism in human leucocytes was strongly stimulated by IgG, independent of whether phagocytosis occurred or not. The percentage increase was highest in the pentose phosphate pathway. Maximum stimulation of the glucose oxidation occurred with an IgG concentration of 1-4 g/l. The insignificant effect of F(ab')2 fragments indicated that the Fc piece is necessary for the stimulation by IgG. In nonphagocytosing leucocytes, serum stimulated the lactate production more and the CO2 production less than indicated by the IgG content of the serum. During phagocytosis or with high IgG concentrations, serum increased the glucose oxidation to a greater extent than did IgG alone. These results indicate that IgG is one of the components in serum most important for the stimulation of glucose oxidation in leucocytes. Serum factors counteracting the stimulation of glucose oxidation by IgG in nonphagocytosing leucocytes may have a regulating effect in vivo.