Fig. 2.

Amot DNA vaccination inhibits tumor growth. (A) WT BALB/c mice were vaccinated twice with either Amot or control vector pcDNA3 21 and 7 days before s.c. challenge with the TUBO mouse breast cancer cell line. In three independent experiments, Amot vaccination suppressed tumor growth for >150 days in 12 of 18 treated mice; in two mice, tumors recurred 150 days after challenge. (B) To determine whether the induction of the antitumor activities depended on CD4⁺ T cells, we conducted an in vivo T cell depletion of this subset during DNA vaccination. Mice were treated with either anti-CD4 or control IgG before and during vaccinations with Amot or empty vector. The antitumor effect of vaccination against Amot was abrogated in the CD4-depleted mice. The size of tumors in Amot-vaccinated mice receiving control IgG or anti-CD4 Ig was significantly different between 7 and 35 days after challenge (n = 5; P < 0.0001, unpaired Student t test). (C) Amot plasmid vaccination was also performed in μ-chain-deficient BALB/c mice lacking B cells (B cell KO mice). No significant difference in the growth of TUBO tumor cells could be detected between Amot- and control pcDNA3 plasmid-vaccinated mice.