The ENA Screen is a chemiluminescent immunoassay (CLIA), for use on IDS automated analyzers. It is used for the qualitative screening of IgG antibodies directed against SS-A/Ro (60 kDa and 52 kDa), SS-B/La, Sm, U1-snRNP (70 kDa, A and C), Scl-70, and Jo-1 antigens human samples of serum or plasma (EDTA).
Antibodies against extractable nuclear antigens (ENA) represent a large family of non-organ- and non-species-specific autoantibodies. Their detection is of great importance in laboratory diagnosis of systemic rheumatic autoimmune diseases.(1,2,3,4)
From the laboratory point of view, systemic autoimmune diseases are characterized by the presence of anti-nuclear antibodies (ANAs). ANA is the first autoantibody test ordered for patients with suspected systemic autoimmune disorders.
Significantly high-titer positivity for ANAs should be further investigated via testing for anti-ENA and anti-dsDNA antibodies.
It is worthwhile remembering that:
- SS-A and SS-B autoantibody positivity is a diagnostic criterion for Sjögren’s Syndrome and SLE, (7)
- dsDNA and Sm autoantibody positivity is a diagnostic criterion for SLE,(8)
- Jo-1 autoantibody positivity is a diagnostic criterion for dermatomyositis/polymyositis, (9,10)
- Centromere B or topoisomerase (Scl-70) autoantibody positivity is a classification and diagnostic criterion for systemic sclerosis,(11,12)
- RNP autoantibody positivity is a diagnostic criterion for mixed connective tissue disease (MCTD). (13)
- CA von Mühlen, EM Tan. Autoantibodies in the diagnosis of systemic rheumatic diseases. Sem Arthr Rheum 1995; 24: 323-58.
- RL Humbel. Auto-immunité, auto-anticorps et maladie. In : Humbel RL, ed. Autoanticorps et maladies autoimmunes. Paris, France : Edition Scientifiques Elsevier; 1997: 17-20.
- PN Hollingsworth, SC Pummer, RL Dawkins. Antinuclear antibodies. In: Peter JB, Shoenfeld Y, eds. Autoantibodies. Amsterdam, The Netherlands : Elsevier Science BV; 1996: 74-90.
- CA Slater, RB Davis, RH Shmerling. Antinuclear antibodies testing. A study of clinical utility. Arch Int Med 1996; 156: 1421-5.
- RL Humbel. Detection of antinuclear antibodies by immunofluorescence. In : van Venrooij, Maini RN eds. Manual of Biological Markers of Disease. Dordrecht, The Netherlands : Kluwer; 1993: A2:1-16.
- National Committee for clinical Laboratory Standardization. Quality assurance for the indirect immunofluorescence test for autoantibodies to nuclear antigen ( IF-ANA ). Approved Guideline. Wayne, PA: NCCLS I/LA2-A, vol. 16(11); 1996.
- C Vitali , S Bombardieri , R Jonsson, H Moutsopoulos , E Alexander, S Carsons, T Daniels, P Fox, R Fox, S Kqassan, S Pillemer, N Tadal, and M Weisman. Classification criteria for Sjögren’s syndrome : a revised version of the European criteria proposed by the American-European Consensus Group. Ann Rheum Dis. 2002 June; 61 (6): 554-558.
- M Petri. Review of Classification Criteria for Systemic Lupus Erythematosus. Rheumatic Disease Clinics of North America; volume 31, issue 2, May 2005, Pages 245-254. Systemic Lupus Erythematosus.
- FW Miller, LG Rider, PH Plotz, DA Isenberg and CV Odds. Diagnostic criteria for polymyositis and dermatomyositis. The Lancet, Volume 362, Issue 9397, 22 November 2003, page 1763.
- K Tanimoto, K Nakano, S Kano, S Mori, H Ueki, H Nishitani, et al. Classification criteria for polymyositis and dermatomyositis. J Rheumatology 1995; 22: 668-74.
- EC Leroy, C Black, R Fleishmajer, S Jablonska, T Krieg, TA Medsger, et al. Scleroderma (systemic sclerosis) : classification, subsets, and pathogenesis. J Rheumatol 1996; 23: 2055-62.
- JG Walker, J Pope, M Bron, S LeClercq, M Hudson, S Taillefer, SM Edworthy, O Nadashkevich and MJ Fritzler. The development of systemic sclerosis classification criteria. Clinical Rheumatology 2007; 26, 9, 1401-1409.
- JM Amigues, A Cantagrel, M Abbal, B Mazieres. Comparative study of 4 diagnosis criteria sets for mixed connective tissue diseases in patients with anti-RNP antibodies. J Rheumatol 1996; 23: 2055-2062.