Comparison between multilamellar and unilamellar liposomes in enhancing antibody formation

The effectiveness of two liposomal preparations, multilamellar vesicles (MLV) and unilamellar vesicles (ULV), in enhancing specific antibody formation was compared in this study. The MLV and ULV, prepared in the presence of bovine serum albumin (BSA), were composed of dimyristoyl-lecithin, cholesterol and dicetyl phosphate in a molar ratio of 7:2:1. Excess free BSA was separated from liposome-associated BSA by Blue Sepharose CL-6B column chromatography. The presence of appropriate lamellar structures for each liposome preparation was demonstrated by electron microscopy. The simultaneous injection of control mice with free BSA and 'empty' MLV or ULV failed to elicit a BSA-specific plaque-forming cell (PFC) response. In contrast, animals injected with liposome-associated BSA (MLV-BSA or ULV-BSA) generated a vigorous PFC response; the magnitude of the response induced by BSA entrapped in unilamellar vesicles was significantly higher than that in multilamellar vesicles. These results suggest that the lamellar arrangement of liposomal vesicles may play a role in affecting the magnitude of the potentiated antibody response.