Background/Purpose

Sarcoidosis is a systemic inflammatory disorder of unknown etiology, characterized pathologically by noncaseating epithelioid cell granulomas, primarily affecting the lungs, the eye, the skin, and the lymphatics.  Musculoskeletal manifestations and the immunologic profile in sarcoidosis may mimick those seen in the rheumatic autoimmune diseases.  Hyperglobulinemia and autoantibodies including rheumatoid factor [RF] and anti-nuclear antibodies [ANA] have been reported. Citrullination is a post-translational modification of proteins, in which the amino acid arginine is enzymatically converted to citrulline.  Citrullinated peptides can be found at the site of chronic inflammation and, in the appropriate genetic setting, can elicit an autoimmune response.  Anti-cyclic citrullinated peptide antibodies [ACPA] are thought to be a new and more specific marker than RFs in rheumatoid arthritis [RA] and have been added to the new RA classification criteria.  The occurrence of ACPA in sarcoidosis has not previously been described.

Objectives: The aim of this study was to investigate the serologic profile, in particular the serum RFs, ANAs  and ACPA  in patients with sarcoidosis attending the rheumatology and/or pulmonary clinics.

Methods:

We retrospectively reviewed the charts of 73 patients with the diagnosis of sarcoidosis and recorded the clinical manifestations and the immunological profile including  ANA, RF, and ACPA.

Results:

Forty one percent of patients with sarcoidosis [30/73] had a positive ANA, with titers ranging from weakly positive [1/40] to high positive [1/1280]. RF and ACPA were not available on all patients.  RF was found in 22 % of patients [13/59] while ACPA was found positive at moderately elevated titers in 8% of patients  [2/24] in the absence of RA. One patient with RA with positive CCP was excluded from the analysis. One patient  had Sjogren syndrome and one had systemic lupus erythemathosus. In addition, 22% of the patients had sarcoid arthropathy.

Conclusion:

ANAs, RFs and ACPA were found in sarcoidosis patients at titers within the range found  in the rheumatic ADs.   ACPA was present in 8% of sarcoidosis patients in the absence of RA. We suggest that investigation of the autoantibody signatures  responsible for the serologic overlap between sarcoidosis and the rheumatic ADs, especially ACPA  may be of great interest since , since  inflammation is central in the immune-pathogenesis of sarcoidosis .

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/serologic-and-clinical-overlap-between-sarcoidosis-and-the-rheumatic-autoimmume-diseases/