Antinuclear Antibodies: Marker of Diagnosis and Evolution in Autoimmune Diseases

Lucia M. Sur, PhD; Emanuela Floca, PhD; Daniel G. Sur, PhD; Marius C. Colceriu, BSc; Gabriel Samasca, MD; Genel Sur, MD, PhD

Disclosures

Lab Med. 2018;49(3):e62-e73. 

In This Article

Abstract and Introduction

Abstract

Antinuclear antibodies (ANAs) are autoantibodies that attack self-proteins within cell nucleus structures; their presence in serum may indicate an autoimmune disease. Also, positive ANA test results have been obtained in chronic infectious diseases, cancers, medication-related adverse events, and even healthy individuals. As a result, a correct interpretation of the presence of ANAs is needed.

Identification of ANAs subtypes is an important part of clinical immunology. The presence of ANAs in patient blood specimens is detected using a cell-line substrate from human laryngeal carcinoma (HEp-2 cells). On this substrate, ANAs will bind specific antigens, which will lead to a suggestive fluorescent emission. The fluorescence patterns visualized under the fluorescence microscope can be correlated with certain subtypes of ANA and certain autoimmune diseases.

Depending on the subtype of ANA present in the serum and the targeted antigen, several staining patterns are reported, namely, nuclear patterns, nucleolar patterns, cell cycle patterns, or cytoplasmatic patterns. Identification of a certain pattern can lead to diagnosis of a certain autoimmune disease.

Introduction

Antibodies are proteins produced by lymphocytes B and play a key role in the activity of the immune system. These proteins have the capacity to recognize foreign antigens, or proteins from external structures such as viruses, bacteria, or other germs. In this way, antibodies are a way for the body to defend itself from infectious organisms. After recognizing the antigens, antibodies start to recruit specialized cells and proteins, which will lead to activation of the inflammation cascade—the response of the organism to defend itself.[1,2]

In some pathological conditions, some of these antibodies produced by the human body attack proteins from self-structures. These are called autoantibodies and they mistakenly identify normal structures as being foreign and dangerous. This abnormal immunological response leads to a type of systemic inflammation that leads the organism to fight against itself. Most human bodies contain autoantibodies but in low titers, which represents a normal state of health. In cases of high autoantibody titers, an autoimmune disease can be suspected. Antinuclear antibodies (ANAs) are autoantibodies that attack self-proteins within cell nucleus structures.[1–3]

A positive test result for ANAs may indicate the presence of a systemic autoimmune disease, such as systemic lupus erythematosus (SLE), drug-induced lupus, scleroderma (SS), Sjögren syndrome (SjS), mixed connective tissue disease (MCTD), polymyositis (PM)/dermatomyositis, rheumatoid arthritis (RA), oligoarticular juvenile chronic arthritis, polyarteritis nodosum, or an organ-specific autoimmune disease such as Grave disease, Hashimoto thyroiditis, autoimmune hepatitis, primary biliary cirrhosis (PBC), inflammatory bowel disease, or idiopathic pulmonary fibrosis.

ANAs also have been detected in chronic infectious diseases, including viral infections (parvovirus, hepatitis C), tuberculosis, parasitic infections (schistosomiasis), and bacterial endocarditis. Other factors that yield ANA-positive test results include cancers, markers of the future development of autoimmune disease, certain medications, and having relatives with an autoimmune disease. Also, some healthy persons test positive for ANA: 2% of healthy young women can have a positive test result.[1–3]

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