OBJECTIVE: To investigate whether levels of antibodies to cytokeratin-18 (CK-18) and epidermal keratin (EPK) were raised in patients with rheumatoid arthritis (RA). METHODS: We measured antibodies to CK-18 and EPK in patients with RA and in patients with osteoarthritis (OA), as well as in normal control subjects by means of an enzyme-linked immunosorbent assay. RESULTS: IgA antibodies to both CK-18 and EPK were significantly increased in patients with RA compared with the controls and with patients with OA (P < 0.0001). No difference was noted in the levels of IgG or IgM antibodies to CK-18 or EPK between controls and patients with OA or RA. CONCLUSION: Raised levels of IgA autoantibody to CK-18 and EPK may reflect damage to cytokeratin-containing cells (e.g., in synovial endothelium) and could be a useful disease marker in RA.
OBJECTIVE: To investigate whether levels of antibodies to cytokeratin-18 (CK-18) and epidermal keratin (EPK) were raised in patients with rheumatoid arthritis (RA). METHODS: We measured antibodies to CK-18 and EPK in patients with RA and in patients with osteoarthritis (OA), as well as in normal control subjects by means of an enzyme-linked immunosorbent assay. RESULTS: IgA antibodies to both CK-18 and EPK were significantly increased in patients with RA compared with the controls and with patients with OA (P < 0.0001). No difference was noted in the levels of IgG or IgM antibodies to CK-18 or EPK between controls and patients with OA or RA. CONCLUSION: Raised levels of IgA autoantibody to CK-18 and EPK may reflect damage to cytokeratin-containing cells (e.g., in synovial endothelium) and could be a useful disease marker in RA.