It has been well documented that both natural and synthetic chemotactic peptides can induce lysosomal enzyme release from neutrophils treated with cytochalasin B. These same peptides are also potent inducers of unidirectional movement, as demonstrated by the chemotactic response in Boyden chambers. In this study, the ability of another family of leukocytes, eosinophils, to release lysosomal enzymes and exhibit a chemotactic response to both natural and synthetic chemotactic peptides was examined. A striking fundamental difference between neutrophil and eosinophil chemotaxis and enzyme release was shown using C5a, formyl met-leu-phe (FMLP), and ala-gly-ser-glu (AGSG) peptides. The 50% effective doses (ED50) for chemotactic responses to C5a, FMLP, or AGSG by neutrophils and eosinophils were 0.05 microgram/ml and 1.0 microgram/ml, 10(-12) M and 10(-10) M, and 10(-7) M and 10(-7) M, respectively. At the same concentrations, these peptides (C5a, f met-leu-phe, and ala-gly-ser-glu) induced the following release of glucosaminidase from neutrophils and eosinophils, respectively: 42% and 2%, 42% and 2%, and 29% and 2%. In striking contrast, immune complexes and opsonized zymosan particles induced the release of 39% and 42% of the total glucosaminidase from neutrophils, while eosinophils released 32% and 43% of the total glucosaminidase from immune complexes and opsonized zymosan particles, respectively. These data indicate fundamental differences between neutrophils and eosinophils in unidirectional movement induced by chemotactic factors and enzyme release mechanism(s).