Laboratory Diagnostics of Connective Tissue Diseases and Vasculitides

Connective tissue diseases and vasculitides are chronic inflammatory systemic diseases in which the immune system is involved. In all connective tissue diseases and some important primary vasculitides the immunological component becomes manifest in characteristic autoantibodies. Besides analyses of inflammatory, haematological, urine analytical, chemical, cytological and histological parameters, the laboratory therefore mainly contributes to diagnostics of these diseases by measuring diagnostically useful autoantibodies, based on antinuclear antibodies (ANA) or antineutrophil cytoplasmic antibodies (ANCA). Usually this is accomplished by stepwise combination of a global immunofluorescence assay with cellular substrates (HEp-2 cells or human neutrophils) and specific binding assays to identify the antibody specificities typical for the disease in question. Detection of these autoantibodies supports confirmation or exclusion of the diagnosis, sub-typing of disease entities, prognosis and - less often - longitudinal observation.