Abrogation of antibodies' production and antitumor activity by the depletion of immune cell subsets. (A) Abrogation of antitumor activity by the depletion of immune cell subsets. Depletion of CD4 T lymphocytes showed complete abrogation of the antitumor activity of the qVEGFR vaccine (n = 10). In contrast, treatment with anti-CD8, anti-NK, or isotype controls (IgG2a and IgG2b) had no effect. Results showed the tumor volume on day 26 after tumor cell injection (mean ± SEM). (B) Abrogation of antibody production by the depletion of immune cell subsets. Sera obtained from mice immunized with qVEGFR were tested against qVEGFR (□) or mVEGFR (▪) by ELISA on day 7 after the fourth immunization. Treatment with anti-CD4 can abrogate the elevation of antibodies against qVEGFR and mVEGFR. In contrast, treatment with anti-CD8, anti-NK, or isotype control had no effect.