Using a novel ex vivo culture system, in which circulating memory CLA+/CLA− T cells are cultured together with autologous lesional or nonlesional epidermal cells with or without streptococcal extract from patients with psoriasis or healthy controls, Ferran et al. [58] found that exposure to streptococcal extracts leads to the activation of key psoriatic T cell-derived cytokines and epidermal chemokines. This evidence concerns the gene SELPLG and psoriasis.