LIPOSOMES AS IMMUNOLOGICAL ADJUVANTS AND VACCINE CARRIERS

Work by numerous laboratories in the last two decades has shown that l iposomes promote humoral and cell-mediated immunity to a large variety of bacterial, protozoan, viral and tumour cell antigens. This immunoa djuvant action of liposomes depends on their structural characteristic s which control vesicle fate in vivo including the mode of antigen int eraction with antigen-presenting cells. Liposomal adjuvanticity is fur ther promoted by receptor mediated targeting to macrophages or the pre sence of co-adjuvants including cytokines. The immunoadjuvant action o f liposomes is supplemented by their ability to act as a carrier for c o-entrapped B and T-cell epitopes, thus eliminating the need for a car rier protein. A technique has been developed recently for the entrapme nt of live microbial vaccines into giant liposomes under conditions wh ich retain their viability. Such liposomes (containing microbial vacci nes and other soluble antigens or cytokines if required) could be used as carriers of vaccines in cases where there is a need to prevent int eraction of vaccines with maternal antibodies or preformed antibodies to vaccine impurities.