Characterization of antibody-dependent cytotoxicity mediated by human alveolar macrophages

Antibody-dependent cellular cytotoxicity is believed to be an important host defense mechanism. Although this reaction has been shown to be mediated by various Fc receptor-bearing effector cells, the ability of a mature macrophage population to mediate this reaction has not been previously demonstrated. In this study, alveolar macrophages obtained from normal subjects by subsegmental lung lavage were used to determine whether this mature macrophage population had the ability to mediate antibody-dependent cell killing. The results of this study demonstrated that alveolar macrophages clearly mediate antibody-dependent cellular cytotoxicity against antibody-coated erythrocyte targets and that the kinetics of the reaction are characteristic of an enzyme-substrate interaction. Furthermore, this study demonstrated that alveolar macrophages are more efficient at mediating antibody-dependent cytotoxicity than is their precursor cell, the peripheral blood monocyte.