Serum specific IgG1, IgG2a, IgG2b and IgG3 levels. Mice (8 animals/group) were subcutaneously injected at weeks 0 and 3 with 100 μg docetaxel, inactivated H1N1 influenza virus vaccine (equivalent to 10 or 100 ng HA) or inactivated H1N1 influenza virus vaccine (equivalent to 10 ng HA) adjuvanted with docetaxel (25, 50, 100 or 200 μg) or alum (200 μg). Blood samples were collected 2 weeks after the second immunization for IgG isotype analysis by indirect ELISA. Values represent mean ± S.D. Significant differences with 10 ng HA groups were designated as *P < 0.05 and **P < 0.01.