Autoantibodies in systemic lupus erythematosus.

The diagnostic role of autoantibodies in SLE differs according to whether they are used to establish the suspected diagnosis or to monitor the course of the disease. At first suspicion of SLE, tests for antinuclear antibodies (ANA) must be carried out. If the ANA test is positive, further specification is required. if the ANA test is negative, SLE can usually be ruled out, since seronegative SLE is extremely rare. If despite a negative ANA test there is compelling clinical evidence of SLE, additional determination of anti-Ro- and anti-ds DNA-antibodies is indicated. Disease course can be monitored using anti-dsDNA-antibody levels in combination with complement C3 and C4 concentrations or CH50. In severe SLE, this should be done at short (4 week) intervals. If a patient is positive for other antibodies known to be associated with disease activity, these antibodies can be monitored individually. Most patients retain a stable antibody pattern, so close monitoring of the entire antibody spectrum is not necessary. 6 months to yearly intervals between tests are usually sufficient.