Immunogenicity of lipid-conjugated antigens. I. The influence of chain length and degree of conjugation on induction of antibody in mice.

An experiments in mice with a range of human serum albumin (HSA) molecules acylated to various degrees with side-chains of 6--20 carbon atoms, the greatest antibody responses against HSA were induced by highly acylated HSA with side-chains of intermediate length (C10--14). Similar results were obtained in rats but in this species the highest acylations with a particular chain length more often induced a less than optimal response. Mouse sera produced in response to acylated antigens and absorbed with HSA itself did not detectably react with acylated HSA when tested by an ammonium sulphate precipitation method. Acylation of antigen may sometimes reduce immunogenicity as shown in experiments with diphtheria toxoid.