Liposomes as immunological adjuvants and vaccine carriers

Work by numerous laboratories in the last two decades has shown that liposomes promote humoral and cell-mediated immunity to a large variety of bacterial, protozoan, viral and tumour cell antigens. This immunoadjuvant action of liposomes depends on their structural characteristics which control vesicle fate in vivo including the mode of antigen interaction with antigen-presenting cells. Liposomal adjuvanticity is further promoted by receptor mediated targeting to macrophages or the presence of co-adjuvants including cytokines. The immunoadjuvant action of liposomes is supplemented by their ability to act as a carrier for co-entrapped B and T-cell epitopes, thus eliminating the need for a carrier protein. A technique has been developed recently for the entrapment of live microbial vaccines into giant liposomes under conditions which retain their viability. Such liposomes (containing microbial vaccines and other soluble antigens or cytokines if required) could be used as carriers of vaccines in cases where there is a need to prevent interaction of vaccines with maternal antibodies or preformed antibodies to vaccine impurities