Antibody Plaque Responses of Mice Given Vibrio cholerae Antigen as Neonates

Abstract

Abstract Neonatal mice were given multiple doses of a lipopolysaccharide (LPS) antigen derived from Vibrio cholerae to induce immunologic tolerance. A direct vibriolytic plaque assay was used to enumerate specific antibody-producing cells to these organisms. Marked suppression occurred in mice given low and high doses, whereas intermediate doses often led to an enhanced response. Normal mice had no “background” antibody-forming cells but many plaque-forming cells (PFC) developed in the spleens of antigen-treated mice before challenge immunization. It was possible to distinguish between antibody-forming cells to the type-specific and the common somatic antigen. After challenge immunization most antibody-forming cells in spleens of control mice had specificity to the type-specific B antigen, whereas mice injected with LPS as neonates showed a suppression of the anti-B response, the number of anti-A PFC being either unaffected or enhanced. Most of the immunosuppression seemed directed to the major type-specific antigen present in the LPS extract. Concomitant stimulation of antibody-producing cells to the common antigen appeared to reflect its presence in smaller “contaminant” amounts. There was little correlation between serum titers and the number of antibody-forming cells.