In Vitro Studies on the Mechanism of Macrophage Migration Inhibition in Tuberculin Sensitivity

Abstract

The mechanism of macrophage migration-inhibition was studied with alveolar macrophages obtained from BCG-sensitized guinea pigs. Sensitivity to migration-inhibition was conferred upon macrophages from normal guinea pigs or upon trypsinized macrophages from sensitized guinea pigs by incubation with either serum or heat eluates prepared from macrophages of BCG-sensitized animals. The migration of passively sensitized macrophages was inhibited only in the presence of specific antigen. Mixtures of PPD and immune serum or macrophage eluates were cytophilic for macrophages but were not demonstrably cytotoxic for mouse L cells. In contrast, supernatants from cultures of antigen-stimulated lymphocytes derived from sensitized guinea pigs were not strongly cytophilic for macrophages but were cytotoxic for L cells. Supernatants from similar cultures of macrophages were less active in inhibiting the migration of normal macrophages. Immunoglobulin was detected in the Sephadex G 200 fractions of macrophage eluates and immune sera which were active in the migration-inhibition test. On the basis of these results it is suggested that macrophage migration-inhibition may involve cytophilic Ab as well as a cytotoxic factor produced by lymphocytes.