Eosinophils play an important role in host defence against helminthic infection. A quantitative system for studying the interactions of eosinophils and a large non-ingestible target was developed using infective muscle-stage larvae of Trichinella spiralis. At 37 degrees, this antibody-dependent system provided a reliable, reproducible index of eosinophil function. Adherence was equivalent under aerobic and anaerobic conditions. No significant differences were noted between peritoneal exudate eosinophils from Trichinella-infected and normal animals. Adherence was inhibited by leukotriene inhibitors [eicosaetraynoic acid (10(-3) M), nordihydroguaiaretic acid (10(-4) M), and BW755C (10(-3) M)] but not by prostaglandin inhibitors (aspirin and indomethacin), suggesting that leukotrienes mediate this eosinophil function. This assay provides another useful method for assessment of a crucial eosinophil function.