Background Anti-actin antibodies (AAA) are well-described as the major component of smooth muscle autoantibodies (microfilament antibodies). They are specially detected in patients with chronic active hepatitis (CAH) and celiac disease (CD). AAA have also been found less frequently in various other autoimmune disorders including systemic lupus erythematosus (SLE), Sjogren's syndrome, and myasthenia gravis, as well as in primary biliary cirrhosis and alcoholic liver disease.

Objectives to study clinicobiological characteristics of patients with AAA in autoimmune inflammatory rheumatic diseases (AIRD).

Methods From January to December 2016, we have collected all cases of patients with AAA presenting for symtomatology of AIRD. The presence of AAA was detected fortuitously by indirect immunofluorescence (IIF) in accordance with its characteristic fluorescence pattern in HEp2 cells (BioRad^©). The specificity for F-actin was confirmed by IIF on rat liver-kidney-stomach sections (Biosystem®) and/or Immunodot (Euroimmun®). Coeliac disease related antibodies were performed in all patients with AAA.

Results Six patients were included: 5 women and a man with a mean age of 43.5 years. AIRD have been suspected in these patients and the mean clinical features were inflammatory polyarthralgia and fever. AIRD was diagnosed in three cases: One patient presented with SLE and two others with rheumatoid arthritis (RA). Hepatic function was disturbed with elevated serum ALT and AST activities in one case higly suspected of CAH. CD was diagnosed in one case. The sixth patient had positive antinuclear antibodies, hypocomplementemia and anti-Ro52, anti-SSB and anti-DFS antibodies associated with FR but didn't fulfilled SLE criteria. The immunological tests showed anti-nuclear antibodies among all patients with high titre and anti-DNA antibodies in SLE and CAH patients respectively. One RA patient had anti-Ro60 antibodies.

Conclusions During our study, AAA were found fortuitously in AIRD. This association is rarely described in the literature. Hepatic involvement can be seen during AIRD. Nevertheless, a CAH and CD associated shouldn't be disregarded.

References

1. Diagnostic value of anti-actin antibodies in a French multicenter study. P.Chretien-Leprince et al; Ann N Y Acad Sci. 2005;1050:266–73.

2. Smooth-muscle antibodies in rheumatoid arthritis. I.Andresen et al; Acta Pathol. Microbiol. Scand. 1980;88: 131–135.

References

Disclosure of Interest None declared