Immunization was done as outlined in Materials and Methods using the indicated immunogens. Irradiated B78-D14 cells as an antigen source were included in each setting. (A) Th1/Th2 cytokines in sera of mice on day 21 after starting immunization. Up to 8 mice were included in each group. For all cytokines tested, the difference between the Surek and the Surek/HB304 group was not significant, while these two groups were different from all other groups with P < 0.005 (Mann-Whitney). (B) Tumor-directed antibodies in sera of mice vaccinated with different immunogens. Binding of serum IgG1 and IgG2a antibodies to melanoma cells was measured by flow cytometry. Mean fluorescence intensities (MFI) are shown as a quantitative measure for antibody coating of tumor cells. Up to 5 animals were included in each group. The columns show means and SEM. Significances (Mann-Whitney) are indicated. The differences between IgG1 titers are not significant. (C) On day 21, mice were challenged with a lethal dose of melanoma cells. The significance is denoted (logrank).