Review Antinuclear Antibodies: Marker of Diagnosis and Evolution in Autoimmune Diseases Laboratory Medicine 49:3:e62-e73 DOI: 10.1093/labmed/lmy016 ABSTRACT Antinuclear antibodies (ANAs) are autoantibodies that attack selfproteins 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, medicationrelated 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 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 Abbreviations ANAs, antinuclear antibodies; SLE, systemic lupus erythematosus; SS, scleroderma; SjS, Sjögren syndrome; MCTD, mixed connective tissue disease; PM, polymyositis; RA, rheumatoid arthritis; PBC, primary biliary cirrhosis; ENAs, extractable nuclear antigens; dsDNA, double-stranded DNA; Sm, Smith antigen; CTDs, connective tissue diseases; IFA, indirect immunofluorescence assay; ELISA, enzyme-linked immunosorbent assay; PML, promyelocytic leukemia protein; SS-CREST, calcinosis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia; snoRNP, small nucleolar ribonucleoprotein; NORs, nucleolar organizing regions; RNAP I, RNA polymerase I. The Oncology Institute, “Prof. Dr. Ion Chiricuță”,2University of Medicine and Pharmacy “Iuliu Hațieganu”3Emergency Clinical Hospital for Children, Cluj-Napoca—Pediatrics II Department,4Emergency Clinical Hospital for Children, Cluj-Napoca—Pediatrics I Department, and 5Regional Institute of Gastroenterology and Hepatology “Octavian Fodor” Cluj-Napoca, ClujNapoca, Romania 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. Keywords: ANA, immunofluorescence, HEp-2, pattern, autoimmunity, marker 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 1 *To whom correspondence should be addressed. surgenel@yahoo.com e62 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 © American Society for Clinical Pathology 2018. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com Downloaded from https://academic.oup.com/labmed/article-abstract/49/3/e62/5032495 by guest on 21 March 2020 Lucia M. Sur, PhD,2,4 Emanuela Floca, PhD,2,5 Daniel G. Sur, PhD,1,2 Marius C. Colceriu, BSc,2 Gabriel Samasca, MD,3 Genel Sur, MD, PhD2,3,* Review such as Grave disease, Hashimoto thyroiditis, autoimmune hepatitis, primary biliary cirrhosis (PBC), inflammatory bowel disease, or idiopathic pulmonary fibrosis. Types of ANA The many known subtypes of ANA can be grouped in 2 main categories, namely, autoantibodies against DNA and histones, and autoantibodies against extractable nuclear antigens (ENAs). The first group includes antibodies against dsDNA (double-stranded DNA) and against histones. Antibodies against dsDNA in high titers are considered to confirm SLE diagnosis. Antibodies against histones indicate drug-induced SLE. The second group includes antibodies against Smith antigen (Sm), wich are specific for SLE, anti– SS-A/Ro, and anti–SS-B/La (these 2 types are specific for Sjögren syndrome, subacute cutaneous SLE, and neonatal lupus syndrome), anticentromere (considered specific for limited cutaneous SS), Jo-1 (considered specific for PM), anti–U3-RNP, and Scl-70 (these final 2 are considered specific for SS). In recent years, more antigens attacked by ANA, such as topoisomerase-I, centromere protein B, and RNA-polymerase I-III, have been described in the literature.4-7 Even if most of them are disease specific, a statistically significant overlap still exists. Tests for ANA Detection Screening tests are used for detection of ANAs in patient serum. The presence of ANAs in blood represents an important criterion for the diagnosis of connective tissue diseases (CTDs). Also, identifying ANA subtypes may be useful in determining a specific CTD. Despite that there are many tests available for detection of ANAs, the ones most commonly used in daily www.labmedicine.com The ELISA test is based on the interaction between antibodies existing in the blood specimen, a preprepared antigen, and special antibodies that are able to stick to the previous 2 components of the final complex, which leads to a color change in the final solution that is proportional to the quantity of ANAs. The results can be positive, equivocal, or negative, based on the determination of the optical density value of the solution.4,8,10,11 IFA is the standard ANA testing method because it is easy to perform, inexpensive, and has high specificity and sensitivity. The presence of ANAs in patient blood specimens is detected using a cell-line substrate from human laryngeal carcinoma (HEp-2 cells). Microscope slides are coated with a monolayer of Hep-2 cells because those cells are a sensitive substrate for ANAs. Those cells confer the following advantages: they are the most sensitive substrate used at the moment, they offer the possibility to identify many patterns, they have better specificity than other methods due to their human origin, they have large nuclei so more details can be seen, all nuclei can be seen, antigens that are produced only in cell division can be more easily identified due to high cell-division rates, and the distribution of antigens is uniform. These slides are incubated with blood specimens, and if the antibodies are present, they will bind to the nuclear antigens. The antigen-antibody complex can be visualized as a distinct pattern in fluorescence microscopy, after adding a fluorescent-labeled antibody that is able to adhere to the complex. The amount of ANAs in the serum specimen is established by determination of antibody titers. ANA titer is determined by diluting the specimens in a buffered solution. Screening tests for ANAs use 1:40 and 1:160 dilutions. If the pattern can be seen in both dilutions, the specimen will continue to be diluted until staining can no longer be seen. The end dilution corresponds to the antibody titer. It is generally considered that a titer of 1:160 is significant for the diagnosis of CTDs. The fluorescence patterns visualized under fluorescence microscope can be correlated with certain autoimmune diseases.2,4,8,11-14 Hep-2 Nuclear Patterns These staining patterns appear as a result of the adhesion of autoantibodies to certain nuclear antigens. Although ANAs are specific to nuclear antigens, in some cases, cytoplasmic patterns correlated with autoantibodies against Lab Medicine 2018;49;e62–e73 DOI: 10.1093/labmed/lmy016 e63 Downloaded from https://academic.oup.com/labmed/article-abstract/49/3/e62/5032495 by guest on 21 March 2020 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 practice are the indirect immunofluorescence assay (IFA) and enzyme-linked immunosorbent assay (ELISA).4,8,9 Review Smooth nuclear membrane pattern in serum of patient with polymyositis. cytoplasmic antigens can also be visualized. Sometimes, a mixed pattern can be observed. Cases in which mitosis-associated patterns may be observed are less common. Smooth nuclear membrane pattern This pattern is characterized by an intense linear fluorescence represented by the nuclear membrane and a less-intense homogeneous fluorescent appearance of the nucleus. In anaphase and metaphase, the chromatin plate result is negative, and greater fluorescent intensity can be seen at the contact between cells. In this pattern, the nucleoli cannot be seen. A fine membranous fluorescence surrounds newly formed nuclei in telophase. The antigens associated with this pattern are lamins A, B1, B2, and C, as well as lamin-associated proteins such as LAP 1A and LAP 2. This pattern has been observed in SLE (Image 1), SS, chronic active hepatitis, seronegative arthritis, and chronic fatigue syndrome.14-16 Punctate nuclear membrane pattern In this pattern, also known as nuclear membrane pores, the nuclear membrane presents granular staining in interphase cells. In anaphase and metaphase, no chromosomal staining can be visualized. The contact surfaces of adjacent e64 Lab Medicine 2018;49;e62–e73 DOI: 10.1093/labmed/lmy016 nuclear membranes emit more powerful fluorescent signals. Frequently, this aspect is associated with mitochondrial antibodies. This pattern can be observed in polymyositis (Image 2) and PBC. In patients with PBC, if testing for anti-Gp210 antibodies yields a positive result, the disease is more aggressive. The most frequent antigen is Gp210, which is a glycoprotein of 210 kDa from nuclear pore complexes. These pores play an important role in substances movement between the cytoplasm and the nucleus. Another antigen identified in this pattern is nucleoporin p62.14,17-19 Homogeneous nuclear pattern Uniform staining across all nucleoplasm is seen in this pattern. The intensity of fluorescence depends on the titer of antibodies in the serum. Sometimes, the nuclear rim can be visualized as a more intense fluorescent emission of the nucleus inner edge. In mitotic cells, chromatin mass is often more intensely stained. Nucleolar staining may yield a positive or negative result and, in some cases, a peripheal nucleolar emission can be observed. Autoantibodies are directed against antigens from dsDNA, histones, or nucleosomes. Although anti-Ku antibodies are more commonly associated with a speckled pattern, in some cases, they are able to show a homogeneous aspect. This www.labmedicine.com Downloaded from https://academic.oup.com/labmed/article-abstract/49/3/e62/5032495 by guest on 21 March 2020 Image 1 Review Punctate nuclear membrane pattern in serum of patient with polymyositis. Image 3 Homogeneous nuclear pattern in serum of patient with systemic lupus erythematosus. pattern is common in SLE (Image 3), RA, lupus induced by hydralazine and procainamide, juvenile chronic arthritis, and SS.14,20-22 Nuclear matrix/large speckled pattern A network of large speckles with a sponge-like aspect characterizes this pattern. Chromatin is not stained in mitotic cells (anaphase, telophase, or metaphase). Nucleoli can be stained or unstained. The nuclear matrix represents a www.labmedicine.com structure made from insoluble proteins resistant to RNAase, DNAase, and high salt treatment. In this pattern, the antigens are heterogeneous ribonuclear proteins. In patients with SLE (Image 4), MCTD, and RA, the autoantigens are represented by hnRNP-A1, hnRNP-A2, hnRNP-B1, and hnRNP-B2. In SS, autoantigens hnRNP-C1, hnRNP-C2, and hnRNP-I have been detected. Usually, nuclear matrix pattern is reported in MCTD but it may also occur in RA, SS, and SLE.14,23,24 Lab Medicine 2018;49;e62–e73 DOI: 10.1093/labmed/lmy016 e65 Downloaded from https://academic.oup.com/labmed/article-abstract/49/3/e62/5032495 by guest on 21 March 2020 Image 2 Review Nuclear matrix/large speckled pattern in serum of patient with systemic lupus erythematosus. Coarse speckled This pattern is characterized by the presence of dense, intermediate-sized speckles and large speckles. The nucleoli are unstained. Cells in mitosis are without staining of the chromatin mass. The antigens identified in this pattern are ribonucleoproteins Sm (U2, U4, U5, U6) and U1RNP. Sm autoantibodies and U1-snRNP (small nuclear ribonucleoprotein) are markers for SLE and MCTD. U2-RNPs are presented in SS-PM overlap, MCTD, SLE, psoriasis (Image 5), and Raynaud phenomenon. In SS and SjS, researchers have identified U4-snRNP and U6-snRNP autoantibodies.14,25,26 Fine speckled Also known as fine granular, this pattern is characterized by fine, tiny speckles emission of interphase nuclei, with a uniform distribution. Nucleoli are mainly unstained; however, in cases of positive anti–SS-B or anti-Ku, some nucleoli may be visualized. Chromatin is not observed in mitotic cells. e66 Lab Medicine 2018;49;e62–e73 DOI: 10.1093/labmed/lmy016 Antigens identified in this pattern are nuclear proteins such as SSA, SSB, Ku, Ki, RNA polymerases II and III, and Mi-2. The diseases associated with this pattern are SLE, SjS, myositis, MCTD, and SS. As many as one-fourth of patients with dermatomyositis (Image 6) present autoantibodies against Mi-2.14,27-29 Dense fine speckled In interphase, characteristic for this pattern are speckles of various size, distribution, and brightness (Image 7). Nucleoli present no staining. Another highly characteristic aspect is the presence of some denser and looser areas of speckles. Mitotic cells present intense speckled fluorescence of the chromosomes. Associated antigens may be LEDGF-p75 (lens epithelium–derived growth factor 75). The exclusive presence of LEDGF-p75 antibodies in the specimen may be useful to identify patients who have no rheumatologic disease, even if the IFA test result is positive.14,30 www.labmedicine.com Downloaded from https://academic.oup.com/labmed/article-abstract/49/3/e62/5032495 by guest on 21 March 2020 Image 4 Review Downloaded from https://academic.oup.com/labmed/article-abstract/49/3/e62/5032495 by guest on 21 March 2020 Image 5 Coarse speckled pattern in serum of patient with psoriasis. Image 6 Fine speckled pattern in serum of patient with dermatomyositis. www.labmedicine.com Lab Medicine 2018;49;e62–e73 DOI: 10.1093/labmed/lmy016 e67 Review Dense fine speckled pattern in interphase in patient serum. Few nuclear dots pattern Centromere pattern An average of 2 (1–6) discrete dots are visualized in interphase. Frequently, these dots are presented near the nucleolus and are known as coiled bodies or Cajal bodies. Those dots represent a distinct pattern from the multiple nuclear dots pattern, despite being found in similar clinical conditions. Antigens identified in this fluorescent aspect are proteins (80 kDa) designated p80-coilin. Particles are associated with fibrillarin and are presumed to have a role in snRNP maturation and transport. Clinical associations: chronic active hepatitis, PBC and, in rare occasions, collagen vascular diseases (Image 8).14,31,32 In interphase, discrete coarse speckles (40–60/cell) spread over the entire nucleus are observed. A block of closely associated speckles is found in the chromatin mass of mitotic cells. Antigens targeted by autoantibodies found in the centromere pattern include CENP-A, -B, -C, -D, -E, -G, and -H. This pattern can be present in limited cutaneous SS-CREST (calcinosis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia; Image 10), PBC and, in rare instances, SjS.35,36 Multiple nuclear dots This pattern is similar to the few-nuclear-dots pattern, but the number of dots is variable, namely, from 6 to 20 per cell (an average of 10/cell). Also, the dots are of variable size. In mitotic cells, the emission is visualized in the cell periphery. More than 30% of patients with PBC are associated with this pattern. Other pathological conditions associated are SjS (Image 9) and, in rare occasions, SLE. Autoantibodies are directed against nuclear multiprotein complexes that include promyelocytic leukemia protein (PML), Sp-100 protein, and NDP53.33,34 e68 Lab Medicine 2018;49;e62–e73 DOI: 10.1093/labmed/lmy016 Hep-2 Nucleolar Patterns Nucleolar homogeneous This pattern involves diffuse, homogeneous fluorescence of the entire nucleolus, with weak, fine granular staining of the nucleoplasm. In mitotic cells, chromatin mass is unstained; however, diffuse cytoplasmic emission is seen. PM-Scl 75 and PM-Scl 100 represent antigens associated with this pattern and are found in patients with myositis-scleroderma overlap syndrome (25%–50% of patients). Another antigen identified is Rpp25, which is a part of the Th/To complex and is associated with SS (Image 11), (4%–10% of patients with limited cutaneous form). Rpp25 have also been reported in SLE, RA, and polymyositis.14,35,37,38 www.labmedicine.com Downloaded from https://academic.oup.com/labmed/article-abstract/49/3/e62/5032495 by guest on 21 March 2020 Image 7 Review Downloaded from https://academic.oup.com/labmed/article-abstract/49/3/e62/5032495 by guest on 21 March 2020 Image 8 Few-nuclear-dots pattern in serum of patient with collagen vascular disease. Image 9 Multiple-nuclear-dots pattern in serum of patient with Sjögren syndrome. www.labmedicine.com Lab Medicine 2018;49;e62–e73 DOI: 10.1093/labmed/lmy016 e69 Review Centromere pattern in serum of patient with limited cutaneous SS-CREST (calcinosis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia). Image 11 Nucleolar homogeneous pattern in serum of patient with scleroderma. e70 Lab Medicine 2018;49;e62–e73 DOI: 10.1093/labmed/lmy016 www.labmedicine.com Downloaded from https://academic.oup.com/labmed/article-abstract/49/3/e62/5032495 by guest on 21 March 2020 Image 10 Review Downloaded from https://academic.oup.com/labmed/article-abstract/49/3/e62/5032495 by guest on 21 March 2020 Image 12 Nucleolar clumpiness in serum of patient with scleroderma. Image 13 Nucleolar speckled/punctated pattern in serum of patient with systemic lupus erythematosus. www.labmedicine.com Lab Medicine 2018;49;e62–e73 DOI: 10.1093/labmed/lmy016 e71 Review Nucleolar clumpiness Nucleolar speckled/punctated Distinct grains with dense distribution are visualized in the nucleoli and are frequently associated with fine speckled nucleoplasmic emission. In metaphase cells, bright spots corresponding to nucleolar organizing regions (NORs) are usually seen within the chromatin body. Regarding antigens (RNAP I/NOR), RNAP I (RNA polymerase I) complex is located inside the nucleoli, and RNAP II and III are located in the nucleoplasm. Due to certain common polypeptides, a cross-reaction between RNAP I, II, and III may by possible. The nucleolar speckled pattern has high specificity for SS (4%–20%), which is often associated with kidney and heart involvement. Other clinical associations are SLE (Image 13), MCTD, and RA.35,41,42 As many as 100 autoantibodies are incriminated in the determination of overt 35 IFA patterns. In addition to nuclear and nucleolar patterns, cytoplasmic patterns have also been described. In several cases, these patterns are mixed due to similar antigenic structures.14 Positive results of ANA testing must be interpreted only in a clinical context because of the possibility of a positive test result in a healthy person, especially in elderly people or in pathological conditions other than autoimmune diseases. In the future it will be important to develop IF methods, to improve the accuracy of discrimination between healthy people who test ANA positive and patients with autoimmune disease LM. References 1. Antinuclear Antibodies (ANA). American College of Rheumatology website. https://www.rheumatology.org/I-Am-A/Patient-Caregiver/DiseasesConditions/Antinuclear-Antibodies-ANA. Accessed April 28, 2018. 2. Medical definition of antinuclear antibody. MedicineNet website. https:// www.medicinenet.com/script/main/art.asp?articlekey=6709. Accessed April 28, 2018. 3. Patient education: Antinuclear antibodies (ANA) (Beyond the Basics). Uptodate website. https://www.uptodate.com/contents/antinuclearantibodies-ana-beyond-the-basics. Accessed April 28, 2018. 4. Kumar Y, Bhatia A, Minz RW. Antinuclear antibodies and their detection methods in diagnosis of connective tissue diseases: a journey revisited. Diagn Pathol. 2009;4:1. 5. Kavanaugh A, Tomar R, Reveille J, Solomon DH, Homburger HA. Guidelines for clinical use of the antinuclear antibody test and tests for specific autoantibodies to nuclear antigens. American College of Pathologists. Arch Pathol Lab Med. 2000;124(1):71–81. 6. Fishbein E, Alarcon-Segovia D, Vega JM. Antibodies to histones in systemic lupus erythematosus. Clin Exp Immunol. 1979;36(1):145–150. Conclusions IFA is the standard ANA testing method because it is easy to perform, inexpensive, and offers high specificity and sensitivity. Also, it has the advantage that the patterns visualized under fluorescence microscope using this method can be correlated with certain autoimmune diseases. These patterns are a result of the adhesion of ANAs to nuclear antigenic structures—this is why they may be associated with certain autoantibodies and certain clinical conditions. Although the IFA presents no organ specificity, it is an important step in the investigation and diagnosis of e72 Lab Medicine 2018;49;e62–e73 DOI: 10.1093/labmed/lmy016 7. Tan EM, Kunkel HG. Characteristics of a soluble nuclear antigen precipitating with sera of patients with systemic lupus erythematosus. J Immunol. 1966;96(3):464–471. 8. Antinuclear Antibody. Medscape website. https://emedicine.medscape. com/article/2086616-overview#a4. Accessed April 28, 2018. 9. Granito A, Muratori P, Quarneti C, Pappas G, Cicola R, Muratori L. Antinuclear antibodies as ancillary markers in primary biliary cirrhosis. Expert Rev Mol Diagn. 2012;12(1):65–74. 10. González-Buitrago JM, González C. Present and future of the autoimmunity laboratory. Clin Chim Acta. 2006;365(1-2):50–57. 11. Emlen W, O’Neill L. Clinical significance of antinuclear antibodies: comparison of detection with immunofluorescence and enzyme-linked immunosorbent assays. Arthritis Rheum. 1997;40(9):1612–1618. 12. Lightfoote MM, Chirmule N, Homburger HA, et al. Quality Assurance of Laboratory Tests for Autoantibodies to Nuclear Antigens: (1) Indirect Fluorescence Assay for Microscopy and (2) Microtiter Enzyme Immunoassay Methods. Approved Guideline–Second Edition. Wayne, PA: Clinical and Laboratory Standards Institute. 2006;26:13. www.labmedicine.com Downloaded from https://academic.oup.com/labmed/article-abstract/49/3/e62/5032495 by guest on 21 March 2020 Clustered granules are observed in the nucleoli. Nucleoplasm is not stained; however, coiled bodies may be seen as nuclear dots. In mitotic cells, chromatin mass is stained. This pattern has a high specificity (5% of patients) for SS (Image 12) and may be detected in pulmonary hypertension. It has been also associated with hepatocellular carcinoma. The identified antigen is fibrillarin, which is a component of snoRNP (small nucleolar ribonucleoprotein) that includes U3snoRNP.39,40 autoimmune diseases. ANAs can also be considered markers of evolution and prognosis, which is why the possibility of correlation between IF patterns and certain autoantibodies conveys a major advantage in clinical evaluation. For example, it has been observed that patients with juvenile idiopathic arthritis who test ANA positive present similar disease characteristics and more frequently develop iridocyclitis, compared with those who test ANA negative. Review 15. AC-11 – Smooth nuclear envelope. International Consensus on ANA Patterns (ICAP) website. https://www.anapatterns.org/view_pattern. php?pattern=11. Accessed April 28, 2018. 30. AC-2 – Nuclear dense fine speckled. International Consensus on ANA Patterns (ICAP) website. https://www.anapatterns.org/view_pattern. php?pattern=2. Accessed April 28, 2018. 16. Konstantinov K, Foisner R, Byrd D, et al. Integral membrane proteins associated with the nuclear lamina are novel autoimmune antigens of the nuclear envelope. Clin Immunol Immunopathol. 1995;74(1):89–99. 31. Fujimoto M, Kikuchi K, Tamaki T, et al. Distribution of anti-p80-coilin autoantibody in collagen disease and various skin diseases. Br J Dermatol. 1997;137(6):916–920. 17. AC-12 – Punctuate nuclear envelope. International Consensus on ANA Patterns (ICAP) website. https://www.anapatterns.org/view_pattern. php?pattern=12. Accessed April 28, 2018. 32. Ogg SC, Lamond AI. Cajal bodies and coilin–moving towards function. J Cell Biol. 2002;159(1):17–21. 18. Dagenais A, Bibor-Hardy V, Senécal JL. A novel autoantibody causing a peripheral fluorescent antinuclear antibody pattern is specific for nuclear pore complexes. Arthritis Rheum. 1988;31(10):1322–1327. 19. Nesher G, Margalit R, Ashkenazi YJ. Anti-nuclear envelope antibodies: clinical associations. Semin Arthritis Rheum. 2001;30(5):313–320. 20. Holborow EJ, Weir DM, Johnson GD. A serum factor in lupus erythematosus with affinity for tissue nuclei. Br Med J. 1957;2(5047):732–734. 21. van Venrooij W, Maini R. Manual of Biological Markers of Disease. Dordrecht: Springer Netherlands; 1996. 22. Isenberg D, Smeenk R. Clinical laboratory assays for measuring antidsDNA antibodies. Where are we now? Lupus. 2002;11(12):797–800. 23. Salden MH, Van Eekelen CA, Habets WJ, Vierwinden G, Van de Putte LB, Van Venrooy WJ. Anti-nuclear matrix antibodies in mixed connective tissue disease. Eur J Immunol. 1982;12(9):783–786. 24. Staněk D, Vencovský J, Kafková J, Raška I. Heterogenous nuclear RNP C1 and C2 core proteins are targets for an autoantibody found in the serum of a patient with systemic sclerosis and psoriatic arthritis. Arthritis Rheum. 1997;40(12):2172–2177. 25. Beck J. Variations in the morphological patterns of “autoimmune” nuclear fluorescence. Lancet. 1961;277(7188):1203–1205. 26. Craft J, Mimori T, Olsen TL, Hardin JA. The U2 small nuclear ribonucleoprotein particle as an autoantigen. Analysis with sera from patients with overlap syndromes. J Clin Invest. 1988;81(6):1716–1724. 27. AC-4 – Nuclear fine speckled. International Consensus on ANA Patterns (ICAP) website. https://www.anapatterns.org/view_pattern. php?pattern=4. Accessed April 28, 2018. 28. Wang J, Satoh M, Kabir F, et al. Increased prevalence of autoantibodies to Ku antigen in African American versus white patients with systemic lupus erythematosus. Arthritis Rheum. 2001;44(10):2367–2370. www.labmedicine.com 33. Zuber M, Heyden TS, Lajous-Petter AM. A human autoantibody recognizing nuclear matrix-associated nuclear protein localized in dot structures. Biol Cell. 1995;85(1):77–86. 34. Sternsdorf T, Guldner HH, Szostecki C, Grötzinger T, Will H. Two nuclear dot-associated proteins, PML and SplOO, are often co-autoimmunogenic in patients with primary biliary cirrhosis. Scand J Immunol. 1995;42(2):257–268. 35. Buchner C, Bryant C, Eslami A, Lakos G. Anti-nuclear antibody screening using HEp-2 cells. J Vis Exp. 2014;88:e51211. 36. AC-3 – Centromere. International Consensus on ANA Patterns (ICAP) website. https://www.anapatterns.org/view_pattern.php?pattern=3. Accessed April 28, 2018. 37. Raijmakers R, Renz M, Wiemann C, et al. PM-Scl-75 is the main autoantigen in patients with the polymyositis/scleroderma overlap syndrome. Arthritis Rheum. 2004;50(2):565–569. 38. Reichlin M, Maddison PJ, Targoff I, et al. Antibodies to a nuclear/ nucleolar antigen in patients with polymyositis overlap syndromes. J Clin Immunol. 1984;4(1):40–44. 39. Yang JM, Hildebrandt B, Luderschmidt C, Pollard KM. Human scleroderma sera contain autoantibodies to protein components specific to the U3 small nucleolar RNP complex. Arthritis Rheum. 2003;48(1):210–217. 40. Ochs RL, Lischwe MA, Spohn WH, Busch H. Fibrillarin: a new protein of the nucleolus identified by autoimmune sera. Biol Cell. 1985;54(2):123–133. 41. Whitehead CM, Winkfein RJ, Fritzler MJ, Rattner JB. ASE-1: a novel protein of the fibrillar centres of the nucleolus and nucleolus organizer region of mitotic chromosomes. Chromosoma. 1997;106(8):493–502. 42. Imai H, Fritzler MJ, Neri R, Bombardieri S, Tan EM, Chan EK. Immunocytochemical characterization of human NOR-90 (upstream binding factor) and associated antigens reactive with autoimmune sera. Two MR forms of NOR-90/hUBF autoantigens. Mol Biol Rep. 1994;19(2):115–124. Lab Medicine 2018;49;e62–e73 DOI: 10.1093/labmed/lmy016 e73 Downloaded from https://academic.oup.com/labmed/article-abstract/49/3/e62/5032495 by guest on 21 March 2020 14. Bradwell A, Hughes R. Atlas of HEp-2 Patterns. Birmingham, England: Binding Site; 2007. 29. Mimori T, Akizuki M, Yamagata H, Inada S, Yoshida S, Homma M. Characterization of a high molecular weight acidic nuclear protein recognized by autoantibodies in sera from patients with polymyositisscleroderma overlap. J Clin Invest. 1981;68(3):611–620. 13. Greidinger EL, Hoffman RW. Antinuclear antibody testing: methods, indications, and interpretation. Lab Med. 2003;34:113–118.