Antibody-dependent cellular cytotoxicity in the rat, rabbit, and guinea pig: relationship of killer (K) cell activity with the presence of Fc+ C3- and Fc+ C3+ lymphocytes.

ADCC of lymphocyte suspensions from the spleen, lymph node, and blood in the rat, rabbit, and guinea pig, was directly correlated with the presence of Fc⁺ C₃^? and indirectly with the presence of Fc⁺ C₃⁺ lymphocyte subpopulations in these preparations. Rabbit lymphocytes, from all three lymphoid compartments, were deficient in the Fc⁺ C₃^? subpopulation but enriched in the Fc⁺ C₃⁺ subpopulation and lacked K-cell activity. A similar lymphocyte profile and lack of K-cell activity was found in the lymph node of the rat and guinea pig. Lymphocytes from the blood and spleen, on the other hand, had a substantial population of Fc⁺ C₃^? lymphocytes and a prominent K-cell activity. The Fc⁺ C₃⁺ lymphocyte, although unable to lyse IgG-coated target cells, is able to compete in vitro with the Fc⁺ C₃^? (K) cell and significantly reduce ADCC. Phagocytic cells lyse very effectively erythroid target cells and contamination by such cells may explain previously reported K-cell activity of rabbit lymphocytes.