Abstract
A macrophage-chemotactic factor (MCFS-1) was purified from delayed hypersensitivity skin sites (DHSS) to bovine γ-globulin in guinea pigs. It was a heat-labile glycoprotein with molecular weight (MW) of 150, 000, having both in vivo and in vitro chemotactic activity. Next, a precursor protein of MCFS-1 was purified from guinea pig plasma. It was a single-chain polypeptide of MW of 160, 000 without chemotactic activity. However, chemotactic activity was generated in the precursor fraction during a 2- or 5-day incubation at 37°C or 4°C, respectively. This generation was inhibited by PMSF, suggesting the role of a serine protease (s) . The serine protease was actually separated from the precursor fraction with a benzamidine-conjugated cellulose affinity column. The protease was of a trypsin-like character with MW of 20, 000. By incubation of the precursor with the protease, macrophage-chemotactic activity which was identical immunologically and physicochemically with MCFS-1, was rapidly generated. It suggests an essential role of the protease to generate MCFS-1 in the DHSS. MCFS-1 was also found to activate macrophages to induce increased glucose consumption, release of lysosomal enzymes, and enhance O2- release due to cytochalasin E and wheat germ agglutinin.
