Suppression of anti‐hapten antibody response in vitro by hapten‐carrier conjugates

Production of antibodies was stimulated or suppressed arbitrarily by antigen treatment in vitro of spleens cultured at various time intervals after in vivo immunization. Spleens of mice immunized to the 2,4‐dinitrophenyl or (4‐hydroxy‐3‐iodo‐5‐nitrophenyl)acetyl haptenic determinants produced antibodies in culture when no antigen was applied in vitro. When a conjugate of the hapten to the same carrier employed for priming was given in vitro, an initial reduction of the response was observed, the level of which was dependent on antigen dose. Subsequently, increased amounts of antibodies were measured. In contrast, in vitro exposure to the hapten conjugated to an unrelated carrier resulted in significant reduction of the response for the entire period of the test. This suppressive effect manifested with various carrier proteins (ovalbumin, bovine IgG, bovine and rabbit serum albumin and keyhole limpet hemocy‐anin), when applied to cultures in doses which were potentially immunogenic.