The effect of tolerance on the specificity of the antibody response and on immunogenicity. Antibody response to conformationally and chemically altered antigens.

Animals were rendered tolerant to human albumin and were then immunized with azo derivatives of human albumin which differed in the number of hapten groups per molecule and in the extent of conformational change. The incidence and specificity of the resulting antibody response was studied and the presence of antibody to azo groups and to conformationally altered protein determinants was demonstrated. Reactivity with the tolerance-inducing antigen was shown to be due to antibodies directed against conformationally altered protein determinants. The difference in the response of tolerant animals to hapten-poor and hapten-rich derivatives was attributed to the extent of conformational alteration. A genetic factor appeared to be implicated in the capacity of tolerant animals to respond to an antigen which cross-reacts with tolerance-inducing macromolecules.