IL17A and asthma: Though they are not the only source of IL-17 production in asthmatic patients, their percentage in PBMCs and IL-17 levels in plasma concentrations correlate with disease severity, so that they could play a role especially in severe or corticoid-refractory forms of asthma (Al-Ramli et al. 2009; Takeda et al. 2009; Zhao et al. 2010; Doe et al. 2010).