IL17A and inflammatory bowel disease: It is commonly accepted that IL17A-producing lymphocytes are extremely relevant in IBD (205); among the different cell populations residing and colonizing (Th17, Th1-Th17, NKT, γδT cells) bowel mucosa in UC or CD, NK cells, and the group 3 of ILC3 (see Table 2) are good producer of IL17A.