Class, amounts, and affinities of anti-dinitrophenyl antibodies in chickens. II. Production of a restricted population of high affinity 7S antibodies by injection of antigen emulsified in adjuvant.

The response of chickens given a single intramuscular injection of maximally coupled dinitrophenylated-gamma-bovine beta-globulin in either Freund's complete (FCA) or incomplete (FIA) adjuvants was characterized by an initial synthesis of 7S and 17S antibodies followed by the exclusive and persistent production of 7S antibodies. The 17S antibodies were not detected either 3 to 4 weeks after a single injection or after an intravenous boost 16 months later. Injections of low doses of antigen in FCA induced the synthesis of 7S antibodies of high affinity at least by 4 months. Analyses of the Sips plots generated from equilibrium dialysis data indicated that a shift in the distribution of 7S antibody affinities occurred because of the production of a restricted population of high affinity antibodies. The changes in the binding properties of antibody during the immune response from chickens given antigen in FIA were less apparent, although qualitatively similar, to those found in birds given antigen in FCA. Three possibilities were presented to explain the effect of adjuvant on the class and affinity of the antibody: a) the requirement of a second signal for B cell differentiation, b) the presence of subpopulation of B cells, and c) somatic mutation events.