THE SIGNIFICANCE OF THE PROTEIN CARRIER IN THE STIMULATION OF DNA SYNTHESIS BY HAPTEN-PROTEIN CONJUGATES IN THE SECONDARY RESPONSE

Abstract

Rabbits were immunized with 2,4-dinitrophenyl (DNP)—protein conjugates. Spleen cell suspensions were prepared and incubated in the presence of various DNP—protein conjugates, the proteins alone, and DNP—lysine. The antigen dependent stimulation of DNA synthesis was used as a measure of the antigenic `activity' of the DNP preparations. It was found that the cells were strongly stimulated by the DNP—protein conjugates used for immunization, and weakly stimulated by the protein alone. Highly substituted DNP—protein conjugates were markedly more effective than lightly substituted conjugates. DNP-conjugates with proteins other than the one used during immunization were inactive. DNP—lysine alone was inactive but inhibited stimulation by the DNP—protein conjugate used for immunization. The significance of these findings is discussed.