Manual of Biological Markers of Disease including Sections C

Manual of Biological Markers of Disease Supplement 2, June 1996

INSTRUCTIONS FOR SUPPLEMENT 2: Preliminary pages Replace: page III/ Title page - page IV / Copyright page (addition ISBN) Add after Table of Contents Section A: New table of Contents Section B Table of Contents Section C Section B Add after Chapter B1.4: Chapter B1.5 Section C Add after Chapter B1.8 Insert tab page Section C Introduction to Section C Chapters C1-C8

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MANUAL OF BIOLOGICAL MARKERS OF DISEASE Edited by

W.J.VAN VENROOIJ University of Nijmegen The Netherlands

R.N. MAINI The Mathilda and Terence Kennedy Institute of Rheumatology London, UK

KLUWER ACADEMIC PUBLISHERS NEW YORK / BOSTON / DORDRECHT / LONDON / MOSCOW

eBook ISBN: Print ISBN:

0-306-46852-2 0-792-33808-1

©2002 Kluwer Academic Publishers New York, Boston, Dordrecht, London, Moscow Print ©1996 Kluwer Academic Publishers Dordrecht All rights reserved No part of this eBook may be reproduced or transmitted in any form or by any means, electronic, mechanical, recording, or otherwise, without written consent from the Publisher Created in the United States of America Visit Kluwer Online at: and Kluwer's eBookstore at:

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Contents

Section C: Clinical Significance of Autoantibodies Introduction 1.

Autoantibodies in Rheumatoid Arthritis: 1.1 Rheumatoïd factor 1.2 Antiperinuclear factor and anti-keratin antibodies 1.3 Anti-RA33 antibodies 1.4 Anti-collagen antibodies

2.

J.S. Smolen

Autoantibodies in SLE 2.1 Autoantibodies to double-stranded DNA 2.2 Autoantibodies to histones, Sm and ubiquitins 2.3 Autoantibodies to Ku and related antigens 2.4 Autoantibodies to PCNA 2.5 Autoantibodies to phospholipids

3.

The Editors

A.J.G. Swaak & R.J.T. Smeenk R.M. Bernstein W.H. Reeves, M. Satoh & J J. Langdon Y. Takasaki & E.M. Tan V. Morris & C. Mackworth-Young

Autoantibodies in SLE-overlap syndromes: 3.1 Autoantibodies to UlsnRNP

F.H.J. van den Hoogen & L.B.A. van de Putte

4.

Autoantibodies in Sjögren’s syndrome: A.G. Tzioufas & H.M. Moutsopoulos Anti-Ro/SSA and anti-La/SSB antibodies

5.

Autoantibodies in Scleroderma: 5.1 Anti-centromere antibodies N. F. Rothfield 5.2 Anti-DNA topoisomerase I antibodies 5.3 Anti-RNA polymerase antibodies 5.4 Anti-nucleolar and other autoantibodies

6.

Autoantibodies in Myositis: 6.1 Transfer RNA synthetases

7.

Autoantibodies in Vasculitis: 7.1 Anti-neutrophil cytoplasmic antibody

8.

I. N. Targoff & P.H. Plotz

C.G.M. Kallenberg

Autoantibodies in other diseases: 8.1 Anti-mitochondrial antibody in primary biliary cirrhosis 8.2 Autoantibodies to the coiled body and other nuclear bodies

I.R.Mackay & M. E. Gershwin

L. E. C. Andrade

Introduction to Section C This, the final section of the Manual, is in a sense the raison d’etre for the existence of the entire Manual. In a series of chapters by clinical specialists it examines the significance of autoantibodies which occur ubiquitously in the sera of patients with rheumatic disease. It has been argued that the value of measuring autoantibodies in clinical practice is predicated by the underlying assumption that the presence of a specific autoantibody equals a distinct disease or syndrome. The extent to which this is true or false is critically examined in this section. We have chosen the major immunologically-mediated disorders as the basis of chapter headings in this section. Within each chapter will be found a personal statement by an expert on the frequency of occurrence and the diagnostic specificity of specific autoantibodies. The emphasis is on a practical approach to how the information may be used in a clinical setting. As Editors, we have sought to impose a template of questions which the authors must address. In some instances this has worked splendidly, but in other chapters, sometimes the know-how/data were not sufficient to adhere to this formula, reflecting the diversity of personal opinions and interpretation. However, we are delighted with the overall result and expect that at the very least, this section will provide a mine of useful, up-to-date information. It will also provide a state-of-the-art approach to the use of laboratory tests as an integral part of clinical evaluation of patients with arthritic disorders and multi-system rheumatic diseases. It will become apparent to the reader and user of this Manual that the apparently simple concept enunciated above is subject to a number of conditions. Not only is there a constellation of autoantigens but there is also a heterogeneity of autoantibodies occurring in a serum sample. For example, a serum may contain an autoantibody of many types of isotypes of immunoglobulin and, as a rule, multiple binding specificities to a welldefined macromolecule and its several epitopes (covered in Section B of the Manual). The sensitivity of detection (a positive test) is determined by the amount, the quality, and the characteristics of the method chosen, be it immunofluorescent microscopy, immunodiffusion, counter-immunoelectrophoresis, ELISA, Western blotting, or immunoprecipitation (covered in Section A of the Manual). More importantly. tricks of the trade in laboratory methods, sharpened by exchange of information on the quality and accuracy of results, help to develop a consensus view of the clinical usefulness of the test. This collective wisdom is especially developed by cooperation at an international level and has led to reference standards being agreed, under the aegis of the World Health Organization, the

International League Against Rheumatism, and the International Union of Immunological Societies. In Europe it has found its focal point in annual workshops which we help to convene. These are based on analysis of clinical samples and have evidently led to a raising of standards in detecting autoantibodies for research and application in clinical practice, by involving opinion formers in these areas. Many of these leaders in the various fields have contributed to one or another part of this Manual. Finally, we again want to thank all contributors to this and other sections. Their labour of love can at last be viewed in the context of the whole Manual. It completes the task we had set ourselves two years ago. We believe all our joint endeavours have resulted in the production of a unique compendium of papers. Our original intension was to produce the three sections as a loose-leaf single Manual, which could be updated in parts. Updates to Section B have already started to be incorporated into the Manual this year, and will continue in the forthcoming years for the rest of the Manual, as originally envisaged. However, it has become evident that putting all three parts together is costly and the resulting Manual may be accessible only to a more restricted readership than we wished. For this reason each section may also be published in due course as a freestanding, more economical, paperback. We are in discussion with the publishers about the possibility of making both formats available; the loose-leaf, mainly as a reference manual held by departmental and institutional libraries, and the single sections, to be more widely used by a nonoverlapping readership as personal copies. R.N. MAINI AND WALTHER VAN VENROOIJ LONDON AND NIJMEGEN JANUARY 1996

Autoantibody Manual C1.1, 1–18. 1996 © 1996 Kluwer Academic Publishers. Printed in The Netherlands.

Autoantibodies in rheumatoid arthritis JOSEF S. SMOLEN Klin. Abteilung für Rheumatologie, Univ.-Klinik für Innerr Medizin III AKH, 1090 Wien, Austria

1. Introduction

Rheumatoid arthritis (RA) is the most frequent chronic inflammatory joint disease. Its prevalence is approximately 1% of populations in the western world. RA is a systemic autoimmune disease characterized primarily by polyarticular, symmetric synovitis. It commonly has a relentlessly progressive course, although exacerbations can often interchange with periods of improvement. Rarely, spontaneous remission may occur. RA joint inflammation leads to cartilage degradation, bone erosions and subsequently to extensive joint destruction and functional impairment which can often result in a bed-ridden state. In addition to joint disease, extrarticular disease is seen in up to 40% of the patients; this can be mild (e.g. rheumatoid nodules) or severe (e.g. vasculitis of internal organs) and includes Felty’s syndrome, in which severe RA is associated with splenomegaly and neutropenia. The diagnosis of RA is based primarily on clinical grounds, however the revised criteria for the classification of RA [1] as formulated by the American Rheumatism Associations (today: American College of Rheumatology. ACR) also include a laboratory measure and one determined by joint imaging. These criteria have a specificity and sensitivity of around 90% in distinguishing RA from other disorders. The pathogenesis of RA is still not fully elucidated. There is increasing evidence that activation of cell-mediated immune reactions with extensive involvement of cells belonging to the macrophage and fibroblast lineages lead to massive secretion of cytokines and consequently of metalloproteinases, these are responsible for the unique, destructive and ‘malignant’ properties of synovial membrane and ‘pannus’ [2]. Moreover, RA is linked to HLA-DR4 or, better, to a sequence in the third hypervariable region of most HLA-DR4 (and DRI) 1ß chains [3], further supporting the concept of the significant involvement of the immune system in RA pathogenesis. The etiology of RA is unknown, however RA is regarded an autoimmune disease on the basis of no extrinsic agent being implicated to date as well as of extensive humoral and cellular immunologic reactions to autoantigens. The clinical aspects of the anti-autoantigen responses to be discussed here will mainly deal with those autoantigens which have been described in the AMAN-C1.1/1

previous sections, i.e. rheumatoid factor(s), anti-perinuclear factor and antikeratin Antibodies, anti-RA33, and anti-collagen antibodies. However, it is clear that not all of these tests are available in all laboratories – more sophisticated assays being performed in institutions which are interested in (basic) sciences and not necessarily in routine laboratories. Moreover, central laboratories may not have the same interest in some tests as departmental laboratories. Finally, laboratories with large sample numbers may have different equipment (and techniques) available than small laboratories and vice versa.

2. Historical aspects

Together with other disorders, Klemperer regarded RA as one of the ‘collagen diseases’ or ‘connective tissue diseases’ on grounds of the presence of ‘fibrinoid’ degeneration with some histochemical characteristics resembling collagen in the connective tissue(s) of joints and nodules in the absence of known inciting agents [4]. Waaler [5] discovered the first autoantibody ever described in RA. These antiglobulins, which were named rheumatoid factor (RF) according to the disease. RFs clearly have differential diagnostic value and are even used to describe major subsets of RA (‘seropositive’ vs ‘seronegative’) or by their invariable absence, a major group of non-rheumatoid inflammatory spinal and joint diseases (‘seronegative spondylarthropathies’). However, an involvement in the pathogenesis of RA is unproven, although according to some authors there may be evidence supporting IP’s on the basis of several indirect indications (see later). At a time when the differences between the multiple subtypes of collagen had not yet been recognized and characterized, Carl Steffen demonstrated the presence of anti-collagen antibodies in patients with RA and put forward the hypothesis that autoimmunity to collagen may be a clue in the pathogenesis of RA [6]. This hypothesis proved to be of lasting importance, since humoral and cellular autoimmune responses to collagen can not only be shown in man 17-91, but also in adjuvant arthritis [10], and animal experiments using collagen type II have resulted in a model of chronic, erosive joint inflammation [ 11]. Steffen speculated that anticollagen-collagen immune complexes, on the basis of their sessile nature in vivo in tissue, could even stimulate rheumatoid factor production. However, it is not clear whether the anti-collagen immune response in RA is a primary one or secondary to the extensive tissue degradation observed in the disease. At about the same time as anti-collagen antibodies were described, the anti-perinuclear factor was detected [12]. Three decades later its antigenic component has come close to characterization [13]. It correlates well with anti-keratin antibodies which were described several years later [14] and whose target antigen is currently unknown and is unlikely to be AMAN-C1 .1/2

cytokeratin but appears to be filaggrin (see section B1.5) (see respective chapter). Both types of autoantibodies have some diagnostic value, but their pathogenetic implications are unknown. Anti-RA33 antibodies have been detected in search for RA-specific antinuclear antibody responses [ 15]. The antigen is a heterogeneous nuclear (hn) RNP (16 and Chapter B1.3). Among the many antibodies to nuclear antigens, including those to Epstein-Barr-Virus related antigens (e.g. EBNA) and histones, it is the most RA-specific one on grounds of its low frequency in healthy and EBV-infected individuals and its prevalence in different rheumatic diseases (see below). None of these autoantibodies is entirely RA-specific and thus none is pathognomonic for RA. In many patients they can occur before disease onset [17]. With the exception of APF and AKA which occur together there is no association between these autoantibodies, and therefore they are complementary in their diagnostic value [13]. Moreover, it is of importance to state here that, although these various autoantibodies can occur also in other inflammatory rheumatic diseases and, for example, RF is a particularly ‘promiscuous’ autoantibody, autoantibodies typical of other rheumatic disorders are never or only rarely observed in RA (other than in the context of a clearly identifiable overlap between RA and another disease).

3. Indications for requesting a test

As stated above. diagnosis of RA is based primarily on clinical grounds and the ACR criteria mentioned contain a laboratory test as only one of seven criteria, four of which must be positive [1]. However, once RA is classifiable according to the ACR criteria, we (i) are commonly already dealing with a clinically diagnosable disease, but (ii) are as yet unable to predict the future fate of the disease in an individual patient, particularly if dealing with patients early in their disease course. In very early stages RA may not be unequivocally recognizable (e.g. asymmetric, monoarticular, oligoarticular, lack of hand joint involvement, lack of erosions despite many months duration). Thus, the use of laboratory tests is of particular importance in such early stages. This is considered especially important because early therapy with disease modifying agents (DMARDs) is almost mandatory today, knowing that the fastest progression of joint destruction occurs in the first few years of the disease [19]. Thus, a main indication for requesting one of the tests commonly positive in RA is differential diagnosis, particularly in early disease stages. It is important to note that, aside from other connective tissue diseases (which are accompanied by characteristic autoantibodies) or a diagnosis of virally induced polyarthritis or reactive arthritis are part of the differential diagnosis of early RA. Reactive arthritis, however, is classified as a ‘seronegative’ arthritis, which indicates that these patients are (virtually always!) AMAN-C1.1/3

negative for rheumatoid factor. In fact, they are also negative for APF, AKA and anti-RA33 (1 5, 17, 18). Therefore, not only positive test results, but also negative ones may be diagnostically helpful, since the vast majority (70–80%) of RA patients are positive for at least one of the above tests even in the early stage [17, 18, 20–22) and a negative test, therefore, speaks against RA. Interestingly, whereas the prevalence of RF is lower in early than in established disease (about 50% in early disease, reaching up to 80% at some time during the course of RA) (20, 21, 23, 24), APF, AKA and anti-RA33 occur in similar frequencies both in early as well as in established disease and are present also in RF-negative RA (14–18, 22); thus these newer autoantibodies increase the sensitivity and specificity of laboratory tests for the diagnosis of RA particularly in its early stages [18, 22]. However, the prevalence of some of these autoantibodies may vary between different ethnic populations [25] and their diagnostic value requires evaluation in its context. Anti-collagen antibodies (ACA) have not been studied extensively in early RA patients. It should also be mentioned, that high titer RF is associated with HLA-DR4 according to some authors [26], whereas other autoantibodies have not yet been clearly shown to be immunogenetically linked.

4. The autoantibodies

4.1 Rheumatoid factor 4.1.1 Assays Among other methods (see chapter B1. 1), RF can be measured by a variety of agglutination techniques. The preferred test for large scale clinical use in many hospitals is nephelometry [27, 28]. Nephelometry is a semi-automated method based upon the principle of increasing light scatter intensity in the nephelometer with increasing agglutination, usually of soluble immune complexes. If the antigen-antibody reaction does not permit the formation of large immune complexes, polystyrene (Latex) particle agglutination intensify the reaction. In nephelometry, polystyrene particles coated with human IgG are used for RF determination. This agglutination depends on the RF content of the serum sample (similar to conventional Latex agglutination tests). The signal of scattered light is proportional to the concentration. The RF level is determined by comparison to standards of known RF concentration. This test is probably the best standardised one today, allows expression of results in IU easily and thus good comparability between different centers. Moreover, rheumatoid factor values obtained by nephelometry agree well with conventional Latex fixation tests [28a]. A test result >40 IU/ml is regarded unequivocally positive in our laboratory on the basis of analyses of control sera (unpublished observations). In larger clinical AMAN-C1.1/4

laboratories in central Europe, nephelometry has more or less replaced other agglutination techniques, including the latex test originally described by Singer and Plotz (29) and, today, is the preferred assay for serial routine clinical use on the basis of its simplicity, accuracy, reproducibility, availability and cost. For smaller series of tests, some laboratories use the latex agglutination test (on a slide) as a screening method, since it is simple and fast to perform. If positive, it can then be followed by the classic Waaler-Rose test (see below). As an alternative to nephelometry and latex agglutination, red cell (RBC) agglutination can be regarded as another assay of choice, e.g. by using human Rh positive RBC coated with anti-Rh serum [30, 31] or according to the classic Waaler-Rose method by coating sheep RBC with rabbit antisheep RBC serum [5, 32]. A positive Rose-Waaler test is more specific for RA than the tests using human IgG, including the latex and similar tests, since anti-allotypic antibodies elicited during pregnancy or by transfusion do not react with rabbit IgG [31, 33]; however, to prevent false positive reactions due to heterophilic antibodies, test sera have to be preabsorbed with sheep RBC for the Wader-Rose test. The result is regarded positive beyond a titer of 1:32, a cutoff point clearly above the results obtained in >95%, of healthy control sera. Some laboratories use a latex tests for screening and then follow with a classic Waaler-Rose test. All these tests usually detect RF of the IgM class (IgM-RF). The sensitivity of the mentioned RF tests is in the order of 50–80% (depending upon disease duration. disease manifestations and test employed, see above). The specificity, when compared to healthy controls, exceeds 95%, but when compared to other connective tissue or chronic infectious diseases is significantly lower. Another very important issue is that of standardisation. In order to optimize a test system it is mandatory to use both clearly positive as well as negative controls and to distinguish as correctly as possible between positive and negative in sera containing concentrations of autoantibodies. here RF. at the border between positive and negative. For this purpose, the WHO Standardisation Committee has provided an international reference preparation of rheumatoid arthritis serum which. by definition, contained 100 international units (IU) per ml (33a). The use of this serum has significantly improved performance of and comparability between laboratories (33b) and is now widely established. 4.1.2 Prevalence Rheumatoid factor production can be induced by either antigenic stimulation (e.g. IgG of immune-complexes) or by polyclonal activation [34, 35]. Therefore RF may have important physiologic functions [35]. The term ‘rheumatoid factor’ was coined for the first time [36] several years after its initial detection in RA [5]. RF can occur in 3% of the general AM AN-C1.1/5

population and about 10–15% of healthy elderly (>60 years of age) individuals (20, 37, 38, Table 1). The prevalence of RF in healthy individuals may differ with ethnic background [39]. Although present in up to 80% of RA-patients, RF can also commonly occur in other rheumatologic and nonrheumatic disorders [20, 38,40–53, Table 1). In lymphoproliferative diseases, but occasionally also in RA and in Sjögren’s syndrome, RF can be monoclonal or oligoclonal[53]. 4.1.3 Clinical and immunogenetic associations As always with laboratory tests, πp clinical context and evaluations of patients is of extreme importance for their interpretation. Given the fact that several diseases, such as SLE, Sjögren’s syndrome, polymyositis, viral infections, etc can be accompanied by a symmetric polyarthritis, it is Table 1. Prevalence of RF (by latex agglutination) in different diseases Disease

Approximate prevalence

RA

80%

Sjögren’s syndrome Mixed eryoglobulinemia Systemic lupus erythematosus Mixed connective tissue disease Polymyositis Systemic sclerosis Juvenile chronic arthritis

70%) 70% 30% 25% 20%) 20%) 15%

Subacute bacterial endocarditis Infectious hepatitis EBV, CMV infections Leprosy Tuberculosis Trypanosomiasis Syphilis Sarcoidosis

40% 25% 20% 25% 15%) 15% 10% 10%

Waldenström’s macroglobulinemia Liver cirrhosis Pulmonary interstitial disease

30% 25% 25%

Healthy controls Elderly (>70 years)

80% of RF-positive patients (reaching up to 100% with B1*0401homozygosity), but only