Isolation and characterization of interleukin-1 from bovine polymorphonuclear leukocytes

Interleukin-1 (IL-1 alpha and IL-1 beta collectively) has been shown to be produced by a wide variety of cell types. The purpose of this study was to evaluate the ability of bovine polymorphonuclear leukocytes (PMNs) to synthesize and release IL-1-like cytokines and characterize the active molecule(s). Purified peripheral blood PMNs were cultured for various periods of time in the presence of opsonized zymosan particles. The resulting culture supernatants exhibited IL-1 activity as determined by enhanced mitogen-induced proliferation of the D10 G4.1 murine T-helper cell line. Supernatants from nonstimulated PMNs or PMNs stimulated for less than 6 h did not enhance D10 G4.1 proliferation. The active molecule (PMNIL-1) was isolated by using gel filtration high-performance liquid chromatography (HPLC). Further characterization of the HPLC-purified molecule by SDS-PAGE and isoelectric focusing indicates bovine PMNIL-1 has a molecular weight of 17.8 kd and a pI of 4.1.