Involvement of interleukin-2 and interferon-gamma in the immune response induced by influenza virus iscoms.

Splenocytes from mice primed with influenza virus envelope proteins incorporated in iscoms, as micelles or as infectious virus, were restimulated in vitro with the same antigen. Interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) were assayed in the supernatants of such cultures. Influenza virus iscoms induced IL-2 and IFN-gamma responses in restimulation experiments that were antigen specific and significantly higher than those induced by micelles or infectious virus. Serum samples collected at the end of the experiments were analysed for the antibody response and profile. The antibody titres induced by iscoms were of a similar order of magnitude as those induced by infectious virus, and were about 18 times higher than the titres induced by micelles. In mice immunized with iscoms or infectious virus the most abundant antibodies were of the IgG1 and IgG2a isotype, and the IgE response was low. We conclude that immunization with iscoms stimulates the Th1-like subtype of murine T lymphocytes.