Effect of chemotactic agents on rat and guinea pig eosinophil cytotoxicity in vitro

Purified guinea pig and rat peritoneal eosinophils were examined for their ability to mediate an antibody-dependent cell cytotoxic reaction against 51Cr-labelled chick red blood cells in the presence of N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP), leukotriene B4, eosinophil chemotactic factor of anaphylaxis, or histamine. Guinea pig eosinophils were induced either by repeated intraperitoneal injections of polymyxin B sulphate or by a single intraperitoneal injection of saline. Using subagglutinating concentrations of antibody, the antibody-dependent cell cytotoxic response was significantly enhanced with FMLP, leukotriene B4, and eosinophil chemotactic factor of anaphylaxis. Histamine was without effect. Rat eosinophils were induced either by three intravenous injections of Sephadex G-200 followed by saline intraperitoneally, by a single intraperitoneal injection of saline, or by infection with the parasite Mesocestoides corti. None of the materials examined was able to enhance the cytotoxic activity of the rat eosinophil preparations over the range tested, in the presence of subagglutinating concentrations of antibody. The antibody-dependent cell cytotoxic response of eosinophils from infected animals was significantly reduced compared with those from Sephadex/saline-treated rats. Incubation of eosinophils obtained from infected animals with FMLP in the presence of agglutinating concentrations of antibody restored eosinophil cytotoxicity. None of the other materials was active. It is concluded that the ability of rat and guinea pig eosinophils to be activated in vitro is partly species related and partly due to the method of cell induction. Differences between the two species may be important when establishing animal models of eosinophil function.