29 human intestinal tissues with CRC, 17 with UC and 7 with polyp were stained using immunohistochemistry to evaluate immunoreactivity for IL-17 family relative ligands including IL-17A, E, F and their respective relative receptors such as IL-17RA, IL-17RB and IL-17RC.
Polyp iNKT cells were enriched for interleukin-10 (IL-10)- and IL-17-producing cells, showed a distinct phenotype being CD4<sup>+</sup>, NK1.1<sup>-</sup> CD44<sup>int</sup>, and PD-1<sup>lo</sup>, and they were negative for the NKT cell transcription factor promyelocytic leukemia zinc-finger.
Compared with controls, elevated percentages of total CD8(+) T cells and cytotoxic T lymphocyte (Tc) 1 (IFN-γ(+) ), Tc2 (IL-4(+) ), and Tc17 (IL-17A(+) ) cell subset, and decreased percentages of FOXP3(+) CD8(+) regulatory T cells, were found in both eosinophilic and non-eosinophilic polyps with a Tc2-skewed and Tc1/Tc17-dominated response in eosinophilic and non-eosinophilic polyps, respectively.
Moreover, by using an in vitro culture system of polyp epithelial cells (PECs), IL-17A-induced gene expression was screened in cultured PECs by DNA microarray.