Inhibition of Macrophage Migration by a Skin-Reactive Polysaccharide From BCG Culture Filtrates

A skin-reactive polysaccharide isolated from unheated BCG culture filtrates (GAE) inhibited guinea pig peritoneal exudate cell migration to the same degree as PPD in guinea pigs sensitized 2 to 3 months previously. The hydrolyzed polysaccharide and a second polysaccharide, both skin non-reactive, were inactive in this in vitro model of delayed hypersensitivity. The degree of migration inhibition correlated well with skin test size in recently sensitized (2 to 3 months) animals for both polysaccharide and protein antigens but bore no relationship to serum antibodies. With time, the ability of exudate cells from skin-reactive animals to react in vitro to the polysaccharide antigen disappeared while in vitro reactivity to PPD remained. We conclude that GAE, as well as a number of other polysaccharides, is able to induce and elicit delayed hypersensitivity