Studies on the inhibition of macrophage migration induced by soluble antigen antibody complexes

Mixtures of serum of Freund's complete adjuvant (FCA) immunized guinea pigs and tuberculin PPD consistently inhibited the in vitro migration of peritoneal exudate cells (PEC) of normal guinea pigs. It is shown that this inhibitory effect is due to a soluble complex between an IgG2 antibody and PPD. By separation of PPD on Sephadex G 200 2 peaks were obtained, corresponding respectively to mol wt of at least 800,000 and 25,000, separated by a plateau. Material derived from both peaks and from the plateau was able to form inhibitory complexes with anti PPD IgG2. When a mixture of small mol wt PPD and anti PPD IgG2 was fractionated on Sephadex G 200, the inhibitory activity was recovered in the void region only. The detection of both IgG2 and PPD in the latter was taken as evidence for the presence of a high molecular weight antigen antibody complex. When the mechanism of complex induced inhibition of migration was examined it was found that: complexes act directly on macrophages present in the peritoneal exudate; removal of the Fc fragment of IgG2 by pepsin abolishes its ability to form migration inhibitory complexes; passive sensitization of macrophages with anti PPD IgG2, followed by exposure to PPD does not result in inhibition of migration; in order to obtain migration inhibition, the complexes must be present during the entire migration period. A 2 hr pulse with complexes does not induce permanent inhibition; and the migration inhibitory activity of antigen antibody complexes can be abolished by certain concentrations of puromycin and aminophylline.