Genetic influences on the adjuvanticity of muramyl dipeptide in vivo.

The possibility that the adjuvanticity of N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) is under genetic control in mice was examined. It was observed that MDP markedly enhances the secondary antibody response of BALB/c mice to bovine albumin but has little enhancing effect on C57BL/10Sn (B10) mice under the same conditions. This strain difference was not abolished by variations in the amount of MDP, the immunization protocol, the assay method, or the antigen used. An analysis of inbred and congenic strains showed that the responsiveness to MDP was influenced by at least two genes, one inside and one outside of the major histocompatibility complex. Mice with the C57BL background and/or the H-2b genome responded weakly to the adjuvant action of MDP, whereas those with the BALB/c or C3H background and/or H-2d or H-2k haplotypes responded more strongly. It is anticipated that the analysis of the mechanism of adjuvanticity of MDP will be facilitated by the use of mice that differ in their response to the adjuvant action of MDP.