Antibody Plaque-Forming Cells: Kinetics of Primary and Secondary Responses

Abstract

Numbers of Jerne plaque-forming cells per spleen, serum hemolysin concentrations, and the degree of resistance of the serum hemolysin to degradation by 2-mercaptoethanol have been determined in adult CBA and C₃D₂F₁ mice as functions of time following primary or secondary intravenous sensitization with 4 × 10⁸ sheep erythrocytes. The characteristic secondary response yields fewer PFC and lower serum antibody concentrations than the primary response. When an adequate time interval (9 weeks or more) elapses between primary and secondary antigen injections, the magnitude of the secondary response begins to approach that of the primary. Primary serum hemolysin is mercaptoethanol sensitive (19S immunoglobulin) while secondary serum hemolysin is largely mercaptoethanol resistant (7S immunoglobulin). Generation times of 7 and 9 hr are obtained for plaque-forming cells during the first 4 days of the primary response. A mathematical model is presented which relates numbers of antibody-forming cells to serum hemolysin concentrations. Using the model together with available experimental data, it is concluded that the great majority of the cells producing 7S hemolysin probably are not detected by the Jerne technique, as applied to the spleen.