Protection is thus conferred by secondary signals released by ILCs to induce appropriate immune response: IL-17 and IL-22 produced in response to extra-cellular pathogens induce local production of anti-microbial peptides and recruitment of neutrophils; IFNγ produced during infection by intra-cellular pathogens induces the recruitment of phagocytes etc. NK cells also have cytotoxic properties, that confer protection notably against intra-cellular infections (but also against tumoral cells). This evidence concerns the gene IL17A and infection.