Determination of the therapeutic effect of adoptively transferred tumor-reactive Th1 cells on tumor growth. (A) Tumors from Th1 cell–treated mice (d10, n = 34; d17, n = 34; d13, n = 24) and PBS-treated mice (d10, n = 22; d17, n = 22; d13, n = 12) were measured with a sliding caliper, and tumor area was calculated as product of perpendicular tumor diameters (*P < .05). Data revealed an inhibitory effect of the adoptive Th1-cell transfer on tumor growth from day 13 on. Error bars denote SEM. (B,C) Adoptive transfer of tumor-reactive Th1 cells leads to inhibition of tumor growth. (B) The difference in tumor weight on day 10 (n = 10) and day 13 (n = 10) after tumor cell injection is shown from 1 experiment of 3. Δ indicates reduction or increase of tumor weight in Th1 cell–treated mice compared with PBS-treated mice. (C) The inhibition of tumor growth is shown by analyzing the tumor weight of Th1 cell–treated and PBS-treated mice on day 11 (n = 22) and day 18 (n = 34) after tumor cell injection (*P < .05). Data are the mean of 2 experiments. (D) OVA-primed Th1 cells were injected in CT26-EpCAM tumor-bearing mice. No difference in tumor weight (n = 12) was observed. Δ indicates increase of tumor weight in the Th1 cell–treated group compared with the PBS-treated group. Experiments were performed as described in “Methods.”