The SS-A/Ro 52 kDa test is a chemiluminescent immunoassay (CLIA), for use on IDS automated analyzers. It is used for the quantitative determination of the specific IgG antibodies directed against protein SS-A/Ro 52 kDa in human samples of serum or plasma (EDTA-K3, Heparin-Na or Sodium Citrate).
The extractable nuclear anti-antigen (ENA) autoantibodies represent a large family of non-organ- and non- species-specific autoantibodies, detection of which is of great importance in laboratory diagnosis of systemic rheumatic autoimmune diseases. (1,2,3,4)
Anti SS-A/Ro autoantibodies are the most common of those detected during screening for systemic rheumatic diseases.
The SS-A/Ro antigen is composed of a particle of RNA rich in uridine bonded to a 60 kDa protein(5); another 52 kDa protein participates in the complex via a protein-protein interaction(6).
Anti SS-A/Ro autoantibodies are class IgG polyclonal antibodies that recognise conformational epitopes on the 60 kDa molecule and, to a lesser degree, on the 52 kDa molecule. Half of the anti-SS-A/Ro sera contain direct antibodies against the two components, the remaining half has autoantibodies directed against only one of the two antigens.
Anti-SS-A/Ro 60 kDa antigens are prevalently found in individuals suffering from Sjiogren Syndrome (SS) and in those with systemic lupus erythematosus (SLE)(7). Anti-SS-A/Ro 52 kDa antigens too are commonly found in individuals suffering from SS and from SLE, but unlike the anti-SS-A/Ro 60 kDa antigens, they are also found in patients suffering from systemic sclerosis (8) and with polymyositis and dermatomyositis (8,9). Moreover, anti-SS-A/Ro 52 kDa have been found, but less frequently, in patients suffering from biliary cirrhosis(10) and those suffering with type 1 autoimmune hepatitis(11).
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- E Ben-Chetrit, EKL Chan, KF Sullivan, EM Tan. A 52-kD protein is a novel component of the SS-A/Ro antigenic particle. J Exp Med 1988;167:1560-71.
- E Ben-Chetrit, R Fox, EM Tan. Dissociation of immune responses to the SS-A(Ro) 52-kD and 60-kD polypeptides in systemic lupus erythematosus and Sjögren’s syndrome. Arthr Rheum 1990; 33: 349-55.
- Frank MB, McCubbin V, Trieu E,Wu Y, Isenber DA, Targoff In. The association of anti-Ro 52 autoantibodies with myositis and scleroderma autoantibodies. J Autoimmun 12: 137-142, 1999.
- Rutjes SA, Vree WT Egberts, Jongen P, Van Den Hoogen F, Pruijn GJ, Van Venrooij WJ. Anti-Ro 52 antibodies frequently co-occur with anti-Jo-1 antibodies in sera from patients with idiopathic myopathy. Clin Exp Immunol 109: 32-40, 1997
- Granito A, Muratori P, Muratori L et al. Antibodies to SS-A/Ro 52kDa and centromere in autoimmune liver disease: a clue to diagnosis and prognosis of primary biliary cirrhosis. Aliment Pharmacol. Ther 26(6), 831-838 ( 2007 ).
- Montano-Loza AJ, Shums Z, Norman GL, Czaja AJ. Prognostic implications of antibodies to Ro/SS-A and soluble liver antigen in type 1 autoimmune hepatitis. Liver International 32 ( 1): 85-92 ( 2012 )