Stimulation of cytotoxic T cells by liposomes containing influenza virus or its components.

Since inactivated virus preparations are poor inducers of influenza-specific cytotoxic T cells (Tc), studies were undertaken utilizing artificial vesicles (liposomes) as a means of delivering viral and H-2 antigens in a multivalent form and oriented with respect to a lipid bilayer. Liposomes prepared from extracted mouse cell lipids efficiently incorporated influenza-viral proteins and were not toxic in culture. Using polybrene to promote greater contact of liposomes with cells, liposomes prepared from whole virus could effectively stimulate memory Tc from spleens of intranasally infected mice in vitro. H-2 was not required in the liposomes to obtain stimulation, and its presence did not improve responses, which were always lower than in parallel stimulations using virally infected syngeneic cells. Liposomes prepared from purified influenza virion subunits (haemagglutinin, neuraminidase, matrix protein) were only slightly stimulatory in vitro, and were unable to prime mice for significant Tc memory.