Influence of monovalent cation concentrations on monocyte-mediated ADCC

Monocyte-mediated ADCC was inhibited by ouabain, which blocks active transport of Na+ and K+ by the membrane Na+K+-ATPase. Inhibition of ADCC was incomplete, however, even when monovalent cation transport was completely inhibited. On the other hand, increasing the duration of exposure to ouabain did result in complete inhibition of ADCC. ADCC was also depressed by incubation of monocytes in media with low (less than or equal to 1.5 mEq/l) or high (greater than or equal to mEq/l) K+ concentrations. The results suggest that monocyte ADCC is dependent upon monovalent cation concentrations (secondarily altered by ouabain exposure) but not upon active Na+K+ transport per se. Finally, since monovalent cation transport-related glycolysis accounted for essentially all of the previously observed increase in monocyte glycolysis associated with monocyte ADCC, we hypothesize that exposure of monocytes to sensitizing antiserum in the ADCC assay results in increased monocyte membrane permeability to monovalent cations.