What is the role of antinuclear antibody (ANA) testing in the evaluation of systemic sclerosis (SSc)?

Updated: Nov 11, 2020
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: Dirk M Elston, MD  more...
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Answer

Antihistone antibodies can be observed in the course of systemic sclerosis, but they are not characteristic. The following antinuclear antibodies (ANAs) are characteristic of scleroderma:

  • Antibodies against topoisomerase I DNA (Scl 70) are detected in the serum of patients with systemic sclerosis. The antibodies are detected in two thirds of patients with dSSc and interstitial lung fibrosis.

  • Anticentromere antibodies (ACAs) are most commonly detected in patients with lSSc; in these patients, changes in the heart, kidneys, and lungs (without fibrosis) are observed less frequently than in other patients.

ANAs can be detected in the course of systemic sclerosis. ANAs include antibodies against fibrillarin, a 34-kd protein of ribonucleoprotein U3 RNP; antibodies against the ribonucleoprotein nucleolar 7-2 RNA protein particle Th RNP; and antibodies to 20-110-kd proteins related to preribosomes (PM-Scl). Anti-PM/Scl antibodies are seen in roughly 24% of patients with polymyositis/systemic sclerosis overlap syndrome. They are also found in 3-10% of systemic sclerosis patients. [43, 44] The spectrum of systemic sclerosis-associated ANA differs in patients with and without cutaneous involvement. [45] ANA serum levels in patients with systemic sclerosis are not correlated with disease activity.

Elevated high-sensitivity C-reactive protein appears related to the occurrence of antimitochondrial antibody in these patients. [46]

With capillary microscopy, enlarged capillaries are observed in all 3 portions of the capillary nail fold–arterial, apical, and venous– and especially at the edge of the nail fold. Adjacent areas are avascular.

Spirometry demonstrates functional lung disturbances. In approximately 70% of patients, the DLCO is decreased.


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