A new autoantibody in patients with rheumatoid arthritis: characterization of the anti–hat‐1 antibody system

Abstract

A unique, new autoantibody, anti–HaT‐1, has been identified in the serum of patients with rheumatoid arthritis (RA). Anti–HaT‐1 antibody is predominantly IgM, and reacts by double immunodiffusion with HaT‐1 antigen, an acidic protein in human and rat liver supernatant (MW ∼ 150,000). It was detected in 9 of 38 patients with RA, 2 of 15 patients with RA and Sjögren's syndrome, and none of 92 patients with other connective tissue diseases, indicating that this autoantibody is highly specific for RA.