However, when studying the functional role of IL-9 in psoriasis patients (plaque and guttate forms) in our coculture model (29), we found that, after S. pyogenes activation, the kinetic of IL-9 production measured in CLA+ T cells and epidermal cells coculture supernatants was similar to those of IL-17A and IFN-γ, progressively increasing over time and dependent on MHC class I and class II presentation, which contrasted with the transient IL-9 induction reported before (36). Here, HLA-C is linked to psoriasis.