Peptides Containing Nonnatural Modifications

N-acetylation, carboxamidation, and introduction of peptide bond surrogates are supposed to reduce the susceptibility of peptides to proteases and or generate structures that are more stable in solution and therefore more reactive with antibodies. In some cases, it is enough to introduce an acetyl group at the N-ter-minus end and or a carboxamide group at the C-terminus of the peptide to increase its reactivity with patients' antibodies. For example, it has been observed that peptide 304-324 of...

Anticentromere Antibodies

ACAs that are relevant for scleroderma diagnosis are directed against the centromere-associated proteins (CENP) CENP-A (17 kDa), CENP-B (80 kDa), and CENP-C (140 kDa). CENP-B is the antigen most commonly targeted by ACAs. Autoantibodies directed against other centromeric proteins (e.g., proteins only transiently associated with the centromere) are not included in the diagnostic-category ACAs. The method of choice for detecting ACAs is indirect immunofluorescence (IIF) using monolayers of tumor...

Introduction and Historical Perspective

Systemic lupus erythematosus (SLE) is a multi-systemic autoimmune disease that can involve almost any organ of the human body. The diverse clinical manifestations of SLE are accompanied by a huge number of autoantibodies. The number of antibodies associated with SLE was recently reported to be 116 1 . No other autoimmune disease is similar to SLE with regard to the vast number of autoantibodies linked with it. SLE autoantibodies can react with nuclear, cytoplasmic, and surface cellular antigens...

Immunostimulatory Properties of Dying Cells

There is compelling evidence indicating that both apoptotic and necrotic cells are capable of stimulating immune responses 139-144 . However, signals derived from necrotic cells appear to make these cells more efficient than apopto-tic cells in eliciting immune responses. This concept was initially highlighted by Gallucci et al. 160 , who reported that DCs undergo maturation in vitro and present antigens in a pro-immune manner in vivo upon stimulation by signals from stressed, virally infected,...

Bcell Receptor Editing

After an immature B cell encounters multivalent self-antigen, there may be a one- to two-day delay before it dies by negative selection. During this time the recombinase-activating genes are transcribed, leading to additional light-chain V J DNA rearrangement, and the newly formed light chain replaces the original light chain in the assembled Ig molecules. If this process of receptor editing produces a BCR that is not autoreactive, the cell can proceed in development. Autoantigen-induced...

Ignorance of Lymphocytes to Target Antigen

Many self-reactive B and T cells may exist indefinitely in the peripheral immune system in a naive functional state. For B cells this ignorance condition is due to lack of T-cell help and or access to sufficient antigen T-cell ignorance refers to failure to encounter cognate antigen on professional antigen-presenting cells. With autoreactive lymphocytes recognizing organ- or tissue-specific antigens, ignorance is probably a common way for cells to avoid becoming activated because lymphocytes...

Autoantigen Proteolysis During Apoptosis

In the early 1990s the Rosens and colleagues elegantly demonstrated that specific SLE-associated autoantigens relocalize to surface blebs in cultured cells induced to die by apoptosis upon exposure to UV irradiation 131 . Following this observation, these investigators reported that the nuclear autoantigens PARP and U1-70kDa (70-kDa protein of the U1 ribonucleoprotein particle) were proteolytically cleaved by caspases during apoptosis 132, 133 . These observations led to the hypothesis that...

The Missing Self Hypothesis

Although the early understanding of the role of the MHC in tissue transplantation stemmed from tumor transplantation studies initiated by Snell (1948) (also discussed in Baxter 2000), this model provided far less predictable results than did skin grafting. For example, Furth et al. (1944) reported that while many lymphomas may behave similarly to other transplanted tissues, there were exceptions (Furth et al. 1944) The transplantation pattern of neoplastic cells arising in the same pure stock...

Autoantigen Cleavage During Necrosis

It should be emphasized that the proteolytic modification of intracellular autoantigens is not limited to classical apoptosis or GrB-dependent cytotoxicity. In previous studies we reported the selective cleavage of autoantigens during primary necrosis, secondary necrosis, and caspase-independent cell death with ne-crotic morphology of a variety of cell lines exposed to high levels of mercury, ethanol, hydrogen peroxide, heat, cytotoxic drugs, or apoptotic stimuli in the presence of Z-VAD-fmk...

Autoantibodies in Mixed Connective Tissue Disease

Mixed connective tissue disease (MCTD) or Sharp syndrome combines features of SLE, SSc, and IIM 51 . The sera of these patients contain high titers of antinuclear antibodies (granular fluorescence pattern) directed against U1-RNP. Whether or not the corresponding clinical picture first described by Gordon Sharp in 1971 is really a separate nosological entity remains a subject of debate. Anti-U1-RNP autoantibodies are directed against the U1-snRNP-specific proteins A (34kDa), C (22 kDa), and 68...

ANCAassociated Vasculitides

ANCA-associated vasculitides, which include Wegener's granulomatosis (WG), microscopic polyangiitis (MPA), and Churg-Strauss syndrome (CSS), are characterized by interactions between anti-neutrophil cytoplasm autoantibodies (ANCAs) and neutrophils initiating endothelial and vascular injury. Focal necrotiz-ing lesions are the common vascular pathology of the ANCA-associated disorders. According to the localization and severity of those lesions, a variety of symptoms and signs can be seen. In...

Anti Smooth Muscle Antibodies

Anti-smooth muscle antibodies (anti-SMAs) are directed against cytoskeletal proteins such as actin, troponin, and tropomyosin 20, 21 . They frequently occur in high titers in association with ANAs. However, they are not highly specific for AIH and have been shown to occur in advanced liver diseases of other etiologies as well as in infectious diseases and rheumatic disorders. In the latter cases, titers are often lower than 1 80. In pediatric patients, SMA autoantibodies may be the only marker...

Autoantibodies in Idiopathic Inflammatory Myopathies

The idiopathic inflammatory myopathies (IIMs, autoimmune myositides) comprise a heterogeneous group of rare diseases characterized by skeletal muscle inflammation and a variety of systemic symptoms. The two most common types are dermatomyositis (DM) and polymyositis (PM). The typical features are muscle soreness and increasing muscle weakness that ultimately progresses to muscular atrophy. PM and DM have different pathogenetic bases and histomorpho-logical features DM is characterized by...

Protein Citrullination and Etiopathogenesis of RA

Citrullinated proteins are observed in synovial tissue of RA joints but not in normal joints. Citrulline is expressed intracellularly mainly in the lining and sublining layers or is found in interstitial amorphous deposits of RA synovium 21, 22 . These citrullinated proteins are not filaggrin but were identified as citrullinated forms of the a- and P-chain of fibrin 22 . These results strongly sug gest a possibility that citrullinated fibrins deposited in the RA synovium are the major target of...

Cytotoxic Lymphocyte Granuleinduced Death Pathways

Cytotoxic lymphocytes induce target cell death through several different pathways, including ligation of the Fas receptor on the surface of the target cell, as well as release of proteases (called granzymes) contained in lytic granules within the cytotoxic cell 64 . Transduction of the Fas signal occurs through multiple protein-protein interactions that activate the caspase cascade by inducing processing of caspase-8 and -10 65 . Cytolysis induced via the Fas pathway is thought to be...

Antiproteinase 3 Antibodies PR3ANCAs

Proteinase 3 (PR3) is a multifunctional protein found in the azurophil (primary) granules of neutrophils, in the granules of monocytes, and in the cytoplasm of endothelial cells. Antibodies against PR3 are highly specific for WG. The diagnostic sensitivity of these AABs is dependent on the stage and activity of disease roughly 50 in the inactive initial stage, roughly 60 in active mono- or oligosymptomatic forms (kidney or lung involvement), and virtually 100 in the active generalized phase. A...

Glutamic Acid Decarboxylase

Glutamic acid decarboxylase (GAD) was first detected as an autoantigen in stiff-person syndrome 61 , a neurological disorder characterized by rigidity of the musculature often accompanied by muscle spasms. The syndrome is the result of impairment of inhibitory neuronal systems operating through the neurotransmitter y-amino butyric acid (GABA), and symptoms can be alleviated by drugs that enhance GABA-ergic neurotransmission. It was noted that a proportion of patients with stiff-person syndrome...

Introduction

Immune self-tolerance within the bounds of normal existence (without medical intervention) refers to the failure to develop clinical autoimmune disease while maintaining the capacity to mount robust immune responses to infectious agents. This definition does not mean that a self-tolerant individual is free of autoreactive events, and there is a wealth of evidence that subclinical autoreac-tivities occur in a normally functioning immune system. Autoreactive events may be a reflection of...

Anticalpastatin Antibodies

Calpastatin is an endogenous inhibitor protein of the calcium-dependent cysteine proteinase, calpain. Canadian investigators and authors described independently the presence of autoantibodies to calpastatin in patients with RA and other systemic rheumatic diseases 33, 34 . There have been a number of reports suggesting that calpain may be involved in activating inflammatory processes and pathogenic mechanisms of rheumatic diseases. These studies propose that (1) calpain is increased in synovial...

The Immunologists Dirty Little Secret

At the time the clonal selection theory was proposed, there were two main lines of evidence suggesting that it had significant problems. The first was the issue of adjuvants. Burnet attributed the action of adjuvants to their ability to provide the prolonged maintenance of a depot of antigen or ensure that antigenic determinants are being made accessible at a more or less steady rate for a prolonged period of time (Burnet 1959). He did not seem to fully appreciate the synergistic effects of...

Characteristics Heterogeneity and Subsets of Systemic Sclerosis

Systemic sclerosis (SSc), also called scleroderma, is a generalized autoimmune disorder characterized by vascular damage and fibrosis within the skin and visceral organs, notably the gut, lung, heart, kidney, joints, and muscles. With regard to the extent of skin and internal organ involvement, the pace of disease progression and, consequently, the prognosis, patients with SSc present a high degree of variability. According to the preliminary ACR criteria for the classification of SSc, the...

Relationship of Islet Autoantibodies to Tcell Responses in Type 1 Diabetes

The analysis of islet autoantibodies provides a means by which individuals may be identified at early stages of pancreatic autoimmunity and gives an indication of the risk of development of type 1 diabetes. T cells are likely to be more directly related to diabetes development than are antibodies, but it is unclear to what extent autoantibody secretion reflects a pathogenic T-cell response. Measures of disease-related T-cell responses in diabetes and an understanding of the relationships of...

Comparison of Common Techniques

Indirect immunofluorescence IIF is the most common technique to measure autoantibodies in clinical labs today because it is the technique used in the most common test, screening for antinuclear antibodies ANAs 1 . The substrates used for IIF are primarily tissue culture cells or cryostat organ sections from rodents or primates that are fixed onto glass slides. The substrate is overlaid with a dilution of the test serum, incubated, rinsed, and overlaid with a fluorescein FITC -conjugated...

Racial Ethnic Variations in Frequency Epitope Recognition and Clinical Relevance of Diseaserelated Autoantibodies

Many studies have shown differences in the clinical as well as autoimmunologic presentation of systemic autoimmune diseases by race or ethnicity. This could be explained in part by different distributions of major histocompatibility complex MHC class II alleles as well as polymorphisms of genes coding for immunoglobulins, immune mediators, and regulators or genes coding for the appropriate autoantigen s itself. The distribution of many of the SLE-, SSc-, and myositis-related AABs differs among...

AntiSa Antibodies

Anti-Sa antibodies have been reported as RA-specific autoantibodies that recognized an unknown 50-kDa doublet protein in human spleen and placenta extracts. Anti-Sa antibodies are detected by immunoblotting in 31-43 of RA patients with very high specificity gt 98 26-28 . The target Sa antigen was later identified as a citrullinated vimentin 29 . Therefore, anti-Sa antibodies are reactive with citrullinated proteins as well as APF, AKA, anti-filaggrin, and anti-CCP antibodies. 12.5...

Antitopoisomerase I Antibodies

The so-called anti-topoisomerase I anti-scl-70 antibodies target DNA topoisome-rase I, which is found in the nucleoplasm and nucleolus and catalyzes the cleavage and rebinding of single-stranded DNA during the relaxation phase of supercoiled DNA. Although the name Scl-70 antibody is still used, the scientifically more correct name is anti-topoisomerase I antibody ATA . IIF using HEp-2 cells usually reveals fine granular to homogeneous staining of the nucleoplasm with or without depending on the...

TSBAbs with TBII Activity

The TBII activity present in the sera of patients with GD is most likely due to TSAbs, and they primarily bind to epitopes in the N-terminus of TSHR as demonstrated by using LH CGR-TSHR chimeras. In contrast, the TBII activity found in the sera of patients with HT or PM most likely represents TSBAb activity, and they predominantly bind to epitopes in the C-terminus of the TSHR ECD. This indicates that the TSBAb activity, however, does not always correlate with the TBII activity and vice versa....

Antibodies to Nucleosomes Chromatin

Antibodies to nucleosomes have had a comeback in the last few years. This has to do with both the clinical utility of these antibodies in the diagnosis of SLE and drug-induced lupus DIL and new evidence suggesting that nucleosomes may be major candidate autoimmunogens in lupus. Since it is generally accepted that anti-nucleosome antibodies cause the LE cell phenomenon, they were actually among the first autoantibodies discovered. Of note, autoantibodies against individual components of...

Assays for TSHR Autoantibodies

Passive transfer of immunoglobulins from GD patients to experimental animals caused increased thyroid hormone production 39 . The discovery that autoantibodies were the cause of Graves' disease began the quest to detect, quantify, and characterize these antibodies. Two main assays are used to detect and characterize anti-TSHR autoantibodies. One measures the inhibition of TSH binding TBII to the TSHR, while the other measures the stimulatory activity TSAb of the antibody through cAMP production...

Burnets Selfmarker Hypothesis

Burnet published two editions of his monograph The Production of Antibodies Burnet et al. 1941 Burnet and Fenner 1949 . Both were concise but comprehensive summaries of the current findings pertaining to the character and regu lation of immune responses and included attempts to draft general principles to explain these data. Two major changes in approach were made between the two editions. The first was that Burnets original monograph built on the molecular biochemical understandings of...

Anti Clq Antibodies

C1q 460 kDa , a highly conserved protein, is part of the first component of the complement system. The biological function of C1q is to bind immune complexes via its six globular domains and of a variety of other non-immune activators of the complement system, including CRP, DNA, fibronectin, fibrinogen, and lipopolysaccharides, by its collagen-like region CLR . In immune complexes, C1q is normally bound to Fc regions of IgG in order to fulfill the activation function of C1q within the...

AntiRoSSA and AntiLaSSB

Autoantibodies to the Ro SSA and La SSB antigens were first reported in 1961 in sera from patients with Sjogren's syndrome and in 1969 in SLE patients 92, 93 . Two precipitin reactions in SLE sera were designated Ro and La based on the names of the patients in whom they were first identified 93 . The anti-Ro and anti-La precipitins were shown later to be identical to the anti-SSA and anti-SSB precipitins, respectively, reported in sera from patients suffering from Sjogren's syndrome 94 . Both...

IA2 ICA512 and Phogrin IA2j

Following the identification of GAD as a major 64-kDa protein target for antibodies in type 1 diabetes, other evidence demonstrated the existence of distinct proteins of very similar molecular weight that are also recognized by antibodies associated with the disease 81 . Antibodies to these proteins may even be more closely linked to diabetes development than those to GAD itself. The proteins have been identified as two related proteins of the protein-tyrosine phosphatase family, termed IA-2 or...

Ccp

Luminex Bead Regions

Fig. 8.4 Illustration of ANA profiles in people with rheumatic diseases. The Y-axis shows the percentage of people who are positive for a given autoantibody, while the X-axis is divided into various rheumatic diseases. For example, many people with SLE have numerous antibodies 60 have anti-DNA, 70 have anti-chromatin, 25 have anti-Sm, etc. Some other diseases have less diversity of autoantibodies. Anti-RNP is almost the only autoantibody seen in patients with MCTD. Antibodies to SS-A Ro and...

The PEPscan Technique

To perform a fast concurrent synthesis of peptides for epitope-mapping studies, Geysen et al. 29 introduced a method of linear peptide epitope scanning that can be used for the synthesis of hundreds of peptides on polyethylene pins and direct testing of their antigenic activity without removing them from the support see Section 9.3.2.1 . The initial method used radiation-grafted polyethylene pins arranged in an 8 x 12 matrix with the format and the spacing of a microti-ter plate, which allowed...