B-cell epitopes of Sm autoantigens

In systemic rheumatic diseases, patients develop autoantibodies directed against a variety of cellular components. It is rather remarkable that particular sets of autoantibody specificities are associated with each disease. Therefore, these autoantibody profiles constitute an invaluable tool in the diagnosis of autoimmune diseases. Some of these autoantibody specificities show an exquisite disease-restriction. An archetypal example of these reactivities is the anti-Sm autoantibody specificity which is found exclusively in the sera of patients with systemic lupus erythematosus (SLE). Other specificities show a broader association, such as anti-(U1) RNP antibodies which are found in high titers in patients with mixed connective tissue disease (MCTD) and in low titers in SLE.