Clinical aspects of indirect immunofluorescence for autoimmune diseases

Abstract

Because the most common term used in conversations considering autoimmunity is autoantibodies, it is well-expected that the indirect immunofluorescence assay, which detects antibodies directed against various antigens, is one of our most impressive techniques for investigating autoimmune diseases (AIDs). Roughly speaking, the current literature corroborates that this immunopathologic investigation means that autoantibodies detection makes a considerable contribution to both diagnostic and prognostic aspects of AIDs in the clinical setting. However, it varies between different AIDs, autoantibodies, ethnicities or detection methodologies. Directly focusing on the indirect immunofluorescence assay, we present evidence to support this multidimensional variation regarding the subject via reviewing briefly the best-investigated autoantibodies in the well-documented AIDs, including vasculitis, inflammatory bowel disease, scleroderma, autoimmune hepatitis, primary biliary cirrhosis, systemic lupus erythematosus and Sjögren’s syndrome.

Keywords:

• autoantibodies
• autoimmune diseases
• indirect immunofluorescence

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Key issues

• The indirect immunofluorescence assay consists of two important steps: first, binding of target antigen to specific primary antibodies in the diluted serum sample, and second, recognizing the antigen–antibody conjugates through fluorescein-labeled antihuman antibodies.

• In autoimmune hepatitis-1 patients, both antinuclear antibody (ANA) and smooth muscle antibodies are characterized by a highly dynamic behavior so that their disappearance has been closely corresponded to improvement of either histological or biopsy findings.

• Both anti-LKM1 and anti-LC1 are now included in the diagnostic criteria of autoimmune hepatitis-2 and capable of being considered as a prognostic factor for evaluation of disease activity and the severity of liver inflammation, and as an index of therapeutic response as well; however, anti-LC1 serves as a more teachable marker than anti-LKM1.

• Antimitochondrial antibodies makes it possible, or at least easier, to differentiate PBC from other disease mainly involving liver and biliary tract, such as jaundice, by performing simply an antimitochondrial antibodies test, albeit if provided liver biopsy findings were consistent, but note that the current literature introduces ANA as a more reliable prognostic factor of primary biliary cirrhosis.

• Anti-Scl-70, anticentromere antibodies and antinucleolar antibody have been accepted as the most specific antibodies for primary systemic sclerosis.

• The immunologic compartment of the systemic lupus erythematosus classification directly involves the results of antibody tests, for example, ANA, anti-dsDNA antibody, anti-Smith (anti-Sm) antibody and antiphospholipid antibody.

• Antineutrophil cytoplasmic antibodies positivity is corroborated to correspond more closely with phenotypic and prognostic rather than diagnostic aspects of associated vasculitide.

• There is a multidimensional variation across studies on the prevalence of autoantibodies and their correlation with clinical aspects of autoimmune diseases, and this variation, at least, contains four main dimensions, for example, detection methodology, disease profile, autoantibody and ethnicity.

• Now, we should search for factors to improve the sensitivity of indirect immunofluorescence in diagnostic medicine and hence its application in therapeutic evaluation of autoimmune diseases.

Notes