Liposomal incorporation and immunogenicity of carcinoembryonic antigen

The ability of liposomal carriers to act as immuno-adjuvants for carcinoembryonic antigen (CEA) has been evaluated. Liposomal incorporation was consistent with association with the aqueous phase of the liposome, little if any of the protein being associated with the phospholipid bilayer. The incorporation of CEA within liposomal carriers resulted in immunological recognition in mice at doses (0.1 microgram) significantly less than required in Freund's complete adjuvant (25 micrograms), maximal responsiveness being found with liposomal-CEA preparations containing a lipophilic immunoadjuvant, N-acetyl-muramyl-L-alanyl-D-isoglutamyl-glyceryl-dipalmitate. Such liposomal formulations may have utility as immunoadjuvants for cancer immunotherapy.