Persistent enhancement of cell-mediated and antibody immune responses after administration of muramyl dipeptide derivatives with antigen in metabolizable oil.

Circulating antibody titers can be increased when the antigen is administered in an aqueous medium with N-acetylmuramyl-L-alanyl-D-isoglutamine (muramyl dipeptide). Results reported here show that cell-mediated immunity can be demonstrated when this synthetic adjuvant or an active analog is injected with an antigen (ovalbumin) in metabolizable squalane emulsion. Under these conditions a lipophilic derivative of muramyl dipeptide was shown to be even more active and to enhance long-lasting immune responses.