Quantity of antibody synthesized in a single cell during the primary immune response

Following immunization of mice with SRBC the kinetics of antibody synthesis by individual immunocompetent cells during the primary immune response were investigated. The diameter of the average hemolytic plaque using a modified Jerne plaquing technique, was taken to be an estimate of the antibody production by a single cell. We found an increase, followed by a decrease, of the average plaque diameter during the primary immune response. The increase of average plaque diameters is probably due to the raised rate of synthesis of antibody molecules. This increase can be accelerated by adjuvants. The decrease late in the primary immune response could be explained by an internally regulated switch from IgM to IgG antibody synthesis. The results are consistent with the mathematical approach of HELLWIG (1,2).