1 Best Practice & Research Clinical Rheumatology Vol. 18, No. 3, pp. 249–269, 2004 doi:10.1016/j.berh.2004.03.007 available online at http://www.sciencedirect.com   Laboratory testing in autoimmune rheumatic diseases Joanna Sheldon* FIMLS, PhD, MRCPath Director of the Protein reference unit, consultant clinical scientist and Honorary senior lectures Protein Reference Unit, St George’s Hospital Medical School, Cranmer Terrace, London SW15 0RE, UK There are a number of pathological conditions in which tissue damage occurs in association with immune activation directed against components of normal tissue. The initial damaging events usually involve cells of the immune system, the T-cells, but the cell damage releases antigens that become targets for an antibody response. The detection and quantification of autoantibodies has become an important component in the diagnosis and management of autoimmune rheumatic diseases such as rheumatoid arthritis, systemic lupus erythematosus, the s