Induction of syngeneic tumour-specific immunity by liposomes reconstituted with L2C tumour-cell antigens.

Liposomes composed of phosphatidylcholine and phosphatidylserine were reconstituted by detergent dialysis with 3 M K Cl extracts of L2C tumour cells. Liposomes containing L2C antigens were as antigenic as intact tumour cells in the elicitation of delayed-type hypersensitivity responses in strain-2 guinea-pigs previously immunized against L2C tumours. Soluble L2C antigens were devoid of immunoprotective activity, whereas the reconstituted liposomes were capable of protecting animals against up to approximately 100 times the minimal lethal dose of tumour cells. Moreover, the reconstituted liposomes were as antigenic and immunoprotective as viable (irradiated) cells.