It was found that IL-17A, IL-17F and IL-22 were increased in peripheral blood mononuclear cells (PBMCs), bronchoalveolar lavage fluid (BALF) and sputum of asthmatic patients, mainly in those with severe asthma (Doe et al., 2010; Chesne et al., 2014; Raedler et al., 2015). Here, IL22 is linked to asthma.