Autoantibodies in SLE. Disease associations

Antinuclear antibodies are an almost universal feature of SLE. Over the years they have been the subject of intensive study to understand the underlying pathogenesis of the disease. It is clear that ANA in the context of lupus are directed against highly selected targets and are not just the result of nonspecific polyclonal B cell activation. Frequently they react with components of nucleoprotein complexes involved in important cellular processes which are very specific targets for autoimmunity in this condition. The antibodies themselves belong primarily to the IgG1 and IgG3 subclasses of immunoglobulin, are high affinity, occur in large amounts, have important associations with particular HLA class II genes and show all the features of an antigen-driven, T cell-dependent immune response. Although at first glance there is a wide range of antibody specificities associated with SLE, in the individual patient the autoantibody profile is much more restricted. Methods to detect these antibodies have provided the clinician with valuable tools to assist both in diagnosis and assessment of lupus patients. It has been possible to recognise distinctive serological subsets within the spectrum of lupus which are associated with certain patterns of disease expression. This can be helpful in determining both disease classification and prognosis.