Novel immunodiagnostics for inflammatory arthritis

Immunodiagnostics play an important role in the differential diagnostics of arthritis but the test results must be interpreted with respect to the clinical context. The detection of antibodies against citrullinated proteins has significantly improved the immunodiagnostics of arthritis, whereas the importance of testing for rheumatoid factor has decreased due to the low specificity. Antibodies against carbamylated or oxidized proteins will expand the immunodiagnostics of arthritis (especially rheumatoid arthritis) in the future. In contrast, the determination of cytokine concentrations in plasma or synovial fluid plays a subordinate role in the differential diagnostics of arthritis. Indirect immunofluorescence continues to be the gold standard in the detection of antinuclear antibodies (ANA) and in the case of positive results further testing for antigen specificity should be carried out. The presence of ANA is not necessarily associated with autoimmune diseases. An example of a non-pathogenic ANA is anti-DFS70 antibodies.