To further investigate the changes in the effector function of circulating CD8 T cells in psoriasis, two in vitro stimulation methods, TCR-dependent (anti-CD3/CD28) and -independent (PMA/ION), were employed to assess the production of cytokines by T cells in vitro, as this varies significantly depending on the type of stimulus used (54–56). This evidence concerns the gene CD8A and psoriasis.