Interactions between salmonellae and macrophages of guinea pigs. IV. Relationship between migration inhibition and antibacterial action of macrophages.

The in vitro macrophage migration inhibition test was used to detect the development of delayed-type hypersensitivity in guinea pigs infected with Salmonella typhimurium. Four different preparations from supernatants of S. typhimurium cultures were used as the antigens in this test. They included the concentrated bacterial antigens, the high-molecular-weight (>50,000) antigens, the ammonium sulfate-precipitated antigens, and the ribonuclease-treated antigens. All four antigen preparations were shown to inhibit the migration of peritoneal macrophages of salmonella-infected (immune) guinea pigs from capillary tubes, in comparison with cells of normal control animals. By use of the high-molecular-weight antigens and the ammonium sulfate-precipitated antigens, the production of the migration inhibition factor(s) was elicited from cultures of lymphocytes obtained from the peripheral blood of immune guinea pigs. The activity of the migration inhibition factor(s) was demonstrated by its ability to inhibit the migration of peritoneal macrophages of normal guinea pigs from capillary tubes. In contrast, normal peritoneal macrophages exposed to products of antigen-stimulated immune lymphocytes did not exhibit an enhanced phagocytic or bactericidal action against virulent S. typhimurium as compared with those of the normal control. The present study indicated that the bacterial antigens responsible for the elicitation of the production of the migration inhibition factor from lymphocytes of immune guinea pigs are inactivated by proteolytic enzymes, but not by ribonuclease, and have molecular weights of >50,000.