Modulation of antibody synthesis by cholera exotoxin: Influence on helper thymocytes

Abstract

This report demonstrates that a major biological influence of cholera exotoxin (CT) on antibody formation to sheep erythrocytes is mediated by the toxin's influence on the helper function of thymic lymphocytes. Hemolytic plaque-forming cell (PFC) responses for lethally X-irradiated mice repopulated with isologous thymus-marrow cell suspensions were stimulated three- to fivefold when 1.0 μg CT was administered at cell transfer. For mice given marrow cells only, CT did not elevate the PFC response; however, CT stimulated as many PFC in spleens of mice given marrow and 1 × 10 7 thymus cells as mice given marrow and 4 × 10 7 thymus cells. In other transfer experiments, depressed PFC responses were observed when irradiated mice were given marrow and thymus cells from donor mice inoculated with CT 24 hr prior to cell preparation and infusion, or given marrow cells from normal mice and thymus cells from CT-treated mice. In contrast, mice given marrow from CT-treated mice and thymus cells from normal mice responded as well as mice repopulated with normal thymus-marrow cell suspensions.