Antibody- and Complement-Dependent Damage to Liposomes Prepared with Bacterial Lipopolysaccharides.

A procedure is described for the preparation of liposomes with either lecithin or sphingomyelin in the presence of various Salmonella minnesota S and R form lipopolysaccharides (antigens). These liposomes release trapped glucose marker when incubated with an appropriate rabbit antiserum (as source of antibodies) and native, is. unheated, guinea pig serum (as source of complement). The extent of marker loss is dependent on the amount of antigen added; treatment of R or S form lipopolysaccharide with alkali markedly reduces the amount necessary for half-maximal sensitization, I e. half-maximal glucose release. The alkali-treated lipopolysaccharides are also effective in "passive" sensitization of liposomes. In this procedure (in contrast to the above which has been designated "active" sensitization), the liposomes are first generated in the absence of any antigen and subsequently incubated with lipopolysaccharide, Both actively and passively sensitized liposomes lose a greater percentage of their trapped glucose when prepared with lecithin than with sphingomyelin. The properties of the lipopolysaccharide liposomes are compared with those containing various ceramide antigens as described previously. [ABSTRACT FROM AUTHOR]