Studies on the adjuvant effect of water-in-oil-in-water (w/o/w) emulsion of sesame oil. 1. Enhanced and persistent antibody formation by antigen incorporated into the water-in-oil-in-water emulsion

Water-in-oil-in-water (w/o/w) emulsion developed in our laboratory is as effective as water-in-oil (w/o) emulsion of Freund's incomplete adjuvant (FIA) in the stimulation of antibody formation. The emulsion is prepared by redispersion of water-in-sesame oil emulsion of an antigen solution in phosphate buffered saline with emulsifier, Tween 80. The emulsion can be stored at 4 degrees C for at least 3 months without any evidence of change in the adjuvanticity and in the w/o/w state. Even a single injection of bovine serum albumin (BSA) in the w/o/w emulsion elicited a high antibody response in mice over the period of almost whole lifespan. 10 microgram BSA in w/o/w could stimulate antibody formation up to 2(12) in hemagglutination titer, while the same dose in free solution did not elicit any detectable antibody. The tissue reactions caused by the w/o/w emulsion at the injected site and in the regional lymph nodes were much less prominent than those by FIA.