The chemical mediation of delayed hypersensitivity skin reaction. II. Characterization of a macrophage-chemotactic factor from bovine gamma-globulin-induced skin reaction in guinea pigs.

Macrophage-chemotactic factors were extracted from delayed hypersensitivity skin lesions induced by bovine gamma-globulin in guinea pigs. The most active factor, MCFS--1, was highly purified and found to be a heat-labile protein with a molecular weight of 150,000 and to possess in vivo as well as in vitro activity. This factor was homogeneous during polyacrylamide gel electrophoresis, and the chemotactic activity was associated exclusively with this band. Further characterization revealed that its isoelectric point was 6.7 to 6.9 and made a single arc in the beta-globulin region with rabbit antiserums against guinea pig serum on immunoelectrophoresis. This factor seemed to be antigenically different from immunoglobulin G (IgG) by immunodiffusion and immunoadsorption. On the other hand, the chemotactic activity of MCFS-2 was adsorbed by neither anti-IgG nor anti MCFS-1 and that of euglobulin fraction was partially adsorbed by anti-IgG. These indicate the presence of at least three types of antigenically different chemotactic factors for macrophages in the extracts of delayed hypersensitivity skin lesions.