Development of Immunological Memory during the Primary Immune Response

Abstract

THE existence of immunological memory has been classically recognized by the appearance of a “secondary” type of antibody response to antigenic challenge of a previously immunized animal. Whereas the kinetics of the early phases of antibody production have been intensively investigated¹, little is known about the development of immunological memory during the early stages of the immune response. Lymphoid cells from animals previously stimulated with an antigen can respond to the same antigen in tissue culture with antibody production², cellular proliferation^3,4 and increased synthesis of DNA⁵. Available evidence indicates that this in vitro response can be taken as evidence for the presence of specific immunological memory⁵. We have investigated the development of this capacity by measuring the incorporation of tritiated thymidine into the DNA of lymphoid cells from immunized rabbits on re-exposure to the antigen in vitro.