Identification of five human lymphocyte subpopulations by their differential binding of various strains of bacteria.

The ability of human peripheral blood lymphocytes to kill antibody-coated Chang liver cells in antibody-dependent cell-mediated cytotoxicity (ADCC) can be blocked with aggregated IgG (agg-IgG) or by soluble immune complexes. Dissociation of aggregates of IgG or immune complexes from the cell surface, however, resulted in partial recovery of the ability both to bind agg-IgG and to kill in the ADCC assay. Our results indicate that “unblocking” of effector cells could occur in vivo when the concentration of circulating immune complexes is lowered.