NEUTROPHIL CHEMOTACTIC N-ACETYL PEPTIDES FROM THE CALPAIN SMALL-SUBUNIT ARE ALSO CHEMOTACTIC FOR IMMUNOCYTES

N-terminal peptides from the calpain small subunit were shown to have dose-dependent chemotactic activity toward several types of leukemia c ells: T cell, B cell, monocyte and granulocyte/monocyte line leukemia cells. In order to prove that chemotaxis is mediated via receptors, a fluorescein-labeled probe was prepared from one of the N-terminal pept ides and its interaction with peripheral leukocytes was estimated by m eans of flow cytometry, resulting in staining not only of neutrophils but also of most of the monocytes and more than half of the T and B ly mphocytes. The results indicate that calpain-derived N-terminal peptid es may be involved in defense mechanisms, inducing chemotaxis of immun ocytes as well as that of neutrophils.