Marked stimulation of lymphocyte-mediated attack on tumor cells by target-directed liposomes containing immune RNA.

A marked stimulation of normal guinea pig lymphocytes was obtained by incubating them with liposomes that contained both antibody to lymphocytes to provide "homing" of the vesicles and immune RNA isolated from guinea pigs immunized with syngeneic line 10 hepatocarcinoma cells. Tumor cell cytotoxicity was monitored by a 51Cr release assay. This target cell delivery of immune RNA by liposomes produced a dose-dependent stimulation up to 12 times that achieved by in vitro methods with naked immune RNA.