STIMULATING ROLE OF TOXOIDS-LADEN LIPOSOMES IN ORAL IMMUNIZATION AGAINST DIPHTHERIA AND TETANUS INFECTIONS

Liposomes have been produced by injecting an ether solution of a mixtu re of lecithin and cholesterol into a diluted solution of prewarmed di phtheria and tetanus toxoids followed by elimination of the stream of ether vapour by vacuum. In a preliminary study, adjuvant effects of li posomes on the systemic and mucosal immune response have been studied. When a mixture of diphtheria toroid (DT) and tetanus toroid (TT) entr apped in liposomes were administered parenterally or orally in rabbit, a significant rise of specific antibodies against both toxoids was no ticed. In monkeys receiving a mixture of DT and TT entrapped in liposo mes orally, the antibody response after two and three ingestions of th is product was mild but when liposomes containing toxoids were adsorbe d with aluminium hydroxide in a similar experiment, a significant rise in the specific antibody response in monkey against both toxoids was recorded. Adult volunteers, similarly receiving a mixture of DT and TT , entrapped in liposomes and adsorbed with aluminium hydroxide have sh own a significant rise in specific circulating antitoxins. In order to compare the efficacy of this technique of human oral immunization wit h the previous method, whereby a plant medicinal seed (LRS) was used a s adjuvant in oral immunization of man, a second group of volunteers w ere simultaneously and similarly treated as suggested previously. The comparative results are discussed in the present report. (C) 1996 The International Association of Biological Standardization.