Dissociation between the Adjuvant vs Mitogenic Activity of a Synthetic Muramyl Dipeptide for Murine Splenocytes

Abstract

A relatively low-molecular-weight synthetic muramyl dipeptide was found to stimulate antibody formation by normal mouse splenocytes immunized with sheep red blood cells in vitro. This material also resulted in a marked stimulation of “background” antibody-forming cells to the erythrocytes in cultures incubated without antigen. In contrast, the muramyl dipeptide, regardless of concentration, did not induce a marked blastogenic response in vitro, as occurs with adjuvants such as bacterial lipo-polysaccharides. These results suggest that the nonspecific immunostimulatory properties of a low-molecular-weight substance such as the muramyl dipeptide tested, which is commonly found in bacterial cell walls, may not be dependent upon mitogenicity.