Adjuvant activity of some nonpyrogenic hydrophobic analogues of muramyl dipeptide in enhancing the primary humoral and cell mediated immune responses in guinea pig model.

Five muramyl dipeptide analogues synthesized by derivatization of gamma-carboxyl of D-isoglutamine residue of MDP into alkyl amides or incorporation of lysine residue at the site via epsilon-NH2 function were evaluated for immuno-adjuvant activity. Derivatization of gamma-carboxyl of D-isoglutamine into butyl, octyl and dibutyl residues stimulated delayed type of hypersensitivity (DTH) response, the maximum stimulation being observed with octyl amide. Introduction of lauryl amide residue abolished DTH response. The antibody response was impaired with all the alkyl amide analogues except for the lysyl amide derivative with which the response was higher than MDP. Correlation was observed between DTH response and macrophage migration.