The influence of amount and avidity of persisting primary antibodies on the secondary response to human serum albumin in rabbits

The primary antibody response in rabbits to human serum albumin (HSA) has been analysed. Doses of 0.04–25 mg were given subcutaneously with Freund's complete adjuvant. Maximum antibody response about 60 days after primary stimulation was independent of the antigen dose given.

After 175 days the amount of persisting antibody was lowest in the animals stimulated with the lowest dose of antigen. The avidity of the antibody was inversely proportional to the antibody titre. Secondary stimulation of all rabbits with 1 mg of HSA intravenously caused secondary antibody responses which were insignificantly different from each other.

It is suggested that the magnitude of the secondary antibody response is determined by the regulatory activity of the circulating antibodies following primary stimulation.