Identification of clonal or oligoclonal T-cell expansions, defined as groups of T cells sharing the CDR3 α- and CDR3 β-chain amino acid sequences, as well as conserved TCR patterns of CD8+ T cells in tissue lesions of autoimmune diseases such as psoriasis, psoriatic arthritis, ankylosing spondylitis or multiple sclerosis (18–20, 24–28), support that autoimmune T-cell activation is driven by disease-specific autoantigens which may be identical in different patients. The gene discussed is CD8A; the disease is psoriatic arthritis.