Peroxidaseless Chicken Leukocytes: Isolation and Characterization of Antibacterial Granules

Abstract

Chicken polymorphonuclear leukocytes (PMNs) from peritoneal exudates, homogenized and centrifuged on sucrose-density gradients, yielded three classes of membrane-bound particles. The largest (1–3 µm in diameter) granules were most numerous and banded in 51% sucrose. Rod-shaped and electron-dense, they were associated with lysozyme and at least three other cationic proteins. The second class (0.3–0.8 µm) banded in 44% sucrose and comprised two types of granules. One type of granule was regularly present and did not contain peroxidase. The other granule, found occasionally, contained peroxidase and apparently originated in contaminating eosinophils. The smallest granules (0.1–0.2 µm) banded in 38% sucrose, were heterogeneous, and contained acid hydrolases. Alkaline phosphatase was absent. Acidic extracts of the largest granules contained lysozyme and cationic proteins; these extracts, at concentrations of 20–35 µg/rnl, inhibited Escherichia coli, Serratia marcescens, and Staphylococcus albus. Evidently one or more of these proteins may be connected with the antibacterial capacity of peroxidaseless PMNs from chickens.