CD4 and Nasal polyposis: Based upon and consistent with the findings of Molet et al. who reported that the main IL-17+ inflammatory cell type in American patients with nasal polyps was the T cell (44), we further analyzed different subtypes of T cells, and unexpectedly observed for the first time that Tc cells (CD3+CD8+) are the major cellular source of IL-17A although a reduced degree of production was also observed in Th cells (CD3+CD4+) and DN (double negative, CD3+CD4−CD8−), as well as smaller amounts in γδT cells and NKT cells.