Immunological properties of synthetic sugar‐polypeptide conjugates. Effect of N‐Lauroyl‐glucosamine residues on immunogenicity

Abstract

Abstract Several mono‐ and disaccharides were tested for their capacity to enhance the immunogenicity of a weakly immunogenic synthetic polypeptide. For this purpose the sugars were attached to the side chains of multichain poly‐ DL ‐alanine as O‐glycosides of serine. Some of the conjugates were essentially non‐immunogenic in rabbits while others, like the unsubstituted polypeptide, were relatively weak immunogens. Antibodies elicited by the latter were directed almost entirely against the serine glycoside residues. Thus, the sugars contributed to the antigenic specificity of the respective conjugate, but were not very efficient in enhancing its immunogenicity. In further experiments, the effect of lipids on the immunogenicity of sugar‐polypeptide conjugates was studied. In addition to the usual sugars, N‐lauroyl‐glucosaminyl‐serine residues were incorporated into the polymers. In all cases, this led to an increase in immunogenicity, which may be due, in part, to the fact that these polymers were highly aggregated. However, in addition to aggregation, a more specific effect of the N‐lauroyl‐glucosamine groups appears to be involved. In most of the polymers the N‐lauroyl‐glucosaminyl‐serine residues also functioned as determinant groups and it could be shown that for the interaction with antibody the fatty acid residue plays an essential role.