Cytotoxic treatment induces IL-17A in human specimens. (A) mRNA levels of IL-17A from untreated or treated patients (17 samples each group) were quantified by quantitative RT-PCR. Data are mean ± SD (n = 20); **, P < 0.01. Student’s t test was used to assess the significance. The experiment was performed three times and representative data are shown. (B and C) Paraffin-embedded sections of matched human colorectal tumors before and after cytotoxic treatment from four patients were stained for IL-17A. The percentage of the IL-17A–positive cells was quantified as a percentage of the total stromal cells (B); P < 0.05. Student’s t test was used to assess the significance. Two representative samples are shown (C). Bars: (C) 100 µm; (C, inset) 25 µm. (D) Protein levels of IL-17A from unmatched chemotherapy treated and untreated colorectal cancer specimens (20 patients in each group) were quantified using immunofluorescence staining. Frozen sections of human colorectal tumors were stained for IL-17A. Nuclei were counterstained with DAPI. Quantification was done by scanning three high-power fields per specimen using ImageJ software. Data are mean ratio of IL-17A area to DAPI area per patient. ***, P < 0.001. Student’s t test was used to assess the significance.