Suppression of delayed type hypersensitivity induction to sheep red blood cells by concanavalin A in mice

An examination was carried out on the in vivo effect of concanavalin A (Con A) on the induction of delayed-type hypersensitivity (DTH) to heterologous erythrocytes in mice. DTH induction was suppressed by an intravenous injection of 100 microng of Con A 1 day before, or simultaneously with immunization. This suppression was mediated by Con-A-activated spleen cells, and also by their cell-free extracts. However, this suppressive effect was abrogated by absorption of cell-free extracts with immunoadsorbent composed of rabbit anti-mouse thymocyte serum (ATS), indicating that suppressive factors for DTH induction make up one of the components extractable from Con-A-activated T cell population.