The obtention of high-titer antibodies of restricted heterogeneity against lysozyme methyl ester in rabbits vaccinated with Micrococcus lysodeikticus

Abstract

Vaccination of rabbits with the Gram-positive bacterium Micrococcus lysodeikticus results in the production of antimicrococcus antibodies of restricted heterogeneity (Van Hoegaerden et al., 1975). Similarly, we observed that intravenous vaccination of rabbits with Micrococcus cells, partially covered with lysozyme methyl ester, induces the production of large amounts of antilysozyme methyl ester antibodies (up to 40 mg per millilitre of serum) of limited heterogeneity. Our results clearly demonstrate that rabbits, hyperimmunized for months with Micrococcus and yielding homogeneous antimicrococcus antibodies, were incapable of mounting any antilysozyme methyl ester antibody response, when vaccinated with free Micrococcus cells and lysozyme methyl ester bound to Micrococcus. In rabbits, immunized from the beginning with free Micrococcus cells and lysozyme methyl ester bound to Micrococcus, the elicited immune response showed a restricted heterogeneity and was predominantly directed at Micrococcus antigenic epitopes. However, those rabbits were equally capable of producing later a high titer of antilysozyme methyl ester antibodies of limited heterogeneity and clonal dominance, under conditions of mixed vaccination with a low free Micrococcus dose and progressively increasing lysozyme methyl ester doses.