AN IN VITRO SYSTEM FOR THE STUDY OF THE MECHANISM OF ANTIGENIC STIMULATION IN THE SECONDARY RESPONSE.

Abstract

The uptake of [(14)C]thymidine by spleen cell suspensions from rabbits previously immunized to heterologous serum proteins is stimulated by the addition of antigen in vitro. This stimulation is specific and dependent upon concentration of antigen. It represents an increased rate of DNA synthesis and cell division by certain cells of the suspension. These cells are large undifferentiated mononuclear cells comprising approximately 1 per cent of the total population. It is suggested that this response is the in vitro counterpart of the cellular proliferation seen in whole animals following the re-injection of antigen. The procedure described provides a quantitative system for the study of the mechanism of antigenic stimulation. Some preliminary experiments are reported.