MODE OF ACTION OF A MYCOBACTERIAL WATER-SOLUBLE ADJUVANT, MAF3

Abstract

The concomitant use of a mycobacterial water-soluble adjuvant, MAF3, at the time of immunization, enhanced anti-hapten antibody production in guinea pigs treated with either heterologous or homologous dinitrophenylated proteins. This may be due to stimulation by the adjuvant of B-cells and/or helper T-cells. The adjuvant activity of MAF3 in anti-hapten antibody production was seen in immunization with a T-independent antigen, DPN-dextran, although it appeared only when a large amount of the conjugated antigen was introduced as the immunizing antigen. Delayed hypersensitivity reactions which require the participation of effector T-cells were also increased by MAF3. When challenged with the same dinitrophenylated protein antigen as the immunizing antigen, the delayed reactions in the skin or cornea were much stronger in animals treated with the antigen plus adjuvant than in control immune animals. The enhancement was seen when T-dependent but not T-independent antigen was used together with the adjuvant at immunization. No delayed hypersensitivity reaction was demonstrated after immunization with DNP-dextran either with or without MAF3. Conjugates of DNP with MAF3 were immunogenic in the production of anti-DNP antibodies in guinea pigs. However, delayed skin reaction in the these animals were induced by challenging injections of the same conjugates as the immunizing antigen or MAF3, the carrier, but not of DNP-GAP, DNP-OA or DNP-Lys. Similar skin reactions were observed in guinea pigs immunized with MAF3 and challenged with the same antigen. Therefore, DNP-MAF3 is defective as a hapten-carrier antigen presumably because of insufficient substitution of antigenic sites of the carrier with the hapten.