**1. Introduction**

Autoantibodies are groups of antibodies that are directed against body's own antigen. These autoantibodies are generated against different types of antigens in various autoimmune diseases. Clinical symptoms of systemic autoimmune diseases are characterized by the involvement of various organs in addition to the production of non-organ specific autoantibodies. These autoantibodies in autoimmune diseases are associated with a specific clinical symptom within a spectrum [1]. Most of the autoantibodies have diagnostic and prognostic importance with respect to their associated disease and all of these are not involve in the pathogenesis of these diseases. Most autoantibodies are mainly used as biological markers for certain disease but they do not actually reflect the pathophysiological process underwent during the course of the disease, **however, many autoantibodies also have a pathogenetic roles such as antinuclear antibodies and anti-tTG antibodies in celiac disease**. For example, autoimmune hepatitis is a chronic disease which is characterized by various clinical, histological as well as immunological characteristics including production of circulating autoantibodies and high serum concentration of gamma globulin [2]. These autoantibodies are very important for the correct diagnosis and classification of autoimmune liver disease [3] and they are not related with the pathogenesis of autoimmune hepatitis. However, some of the systemic autoimmune disease relating these autoantibodies in the sense that their levels are changes during the course of the disease. These include anti-double stranded DNA antibodies in systemic lupus erythematosus (SLE) and anti-neutrophil cytoplasmic autoantibodies in the vasculitis [4]. Other types of antibodies like anti-nucleosome and anti-CIq autoantibodies can function as both markers of the disease activity as well as pathogenic autoantibodies in SLE [5, 6].

The history of the autoantibodies goes back to 1940s, when two types of antibodies (antinuclear antibodies; ANA and rheumatoid factors; RF) were discovered as the serum factors that bind to nuclear antigen IgG, respectively [7, 8]. ANA and RF considered being a diagnostic

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

feature of SLE but their role in disease pathogenesis remains elusive. In the last two decades, the effects of autoimmune diseases have been gown up to such an extent that it can explains both points of views, as clinically and diagnostically. The pathogenic mechanisms of these autoimmune diseases help to contribute to the discovery of new autoantibodies and new area of research, based on diagnostic and prognostic value, have been developed. Determination of these autoantibodies in the diagnosis of autoimmune disease is important because they are sometime showing nonspecific, unclear character and even shared by different autoimmune diseases [9]. For most of the autoimmune diseases, classification criteria include the determination of autoantibody that helps in final diagnosis. They are important not only for diagnostic perspective but also for prognostic value. Some of these autoimmune have been associated with the clinical manifestation of the disease, therefore estimation of these autoantibodies pattern in the patients might helpful to detect severity of the disease that can be useful for the need of correct therapy [10].

autoantibodies plays not only in key pathogenic role in some diseases including SLE and Graves' disease but also found in some disease in which they play minor pathogenic role and can act as important biomarker [17, 18]. Cytokines, in addition to the production of autoantibodies, play important role in the generation of autoimmune response (especially pro-inflammatory cytokines: except multiple sclerosis), they are produced in response to the viral invasion and are deeply involved in various autoimmune process. Under normal condition, anti-cytokine antibodies response have been develop in healthy normal individual that is consider to be normal physiological process to control various immune response. These responses are for limited time initially, and then the concentration of these autoantibodies increases, reaching a threshold and then coming up to its normal concentration after few weeks. This process also occurs in some pathological conditions including autoimmunity and autoantibodies develop as a result of these processes might be used as prognostic marker

Introductory Chapter: Autoantibodies and Their Types http://dx.doi.org/10.5772/intechopen.77328 5

Autoantibodies against various types of cytokines have been described not only in normal individuals but also in patients with different infectious and immuno-inflammatory disease [20]. These include interferon (α, β, and γ), interleukin (α, 2, 4, 6, 8 and 10), nerve growth factor, chemokine (α and β), leukemia inhibitory factor, granulocyte-macrophage colonystimulating factor, and tumor necrosis factor (α and β) and receptor, which are found to be in normal individuals and patients with various disorders. In autoimmune disease, these autoantibodies can function as prognostic biomarkers that may even show negative (autoantibodies against IL-18 and IL-1α in RA) or positive (autoantibodies to IL-6 in systemic sclerosis) results [21]. The autoantibodies against cytokines found to be pathogenic that makes autoimmune patients more susceptible to other diseases. There are various autoimmune diseases including rheumatoid arthritis, multiple sclerosis, systemic sclerosis, SLE, autoimmune polyendocrine syndrome type 1, in which neutralizing autoantibodies against cytokines have been described. The affinity of anti-cytokine autoantibodies may depend on the function of cytokine during various immune responses. For example, pro-inflammatory cytokines such as interleukin-1α, -6, -8, TNF-α and GM-CSF, have more frequently autoantibodies, whereas anti-inflammatory cytokines like interleukin-10 and TGF-β, have autoantibodies that were reported rarely [22–24]. However, most of these studies does not provide sufficient evidences for the functional effects of these autoantibodies, which might helpful to describe their role in various autoimmune diseases and capitalize them for future therapies. There are few proinflammatory cytokines that play important role in joint aggression in rheumatoid arthritis [25, 26]. Autoantibodies against IL-1alpha can be worked as an important prognostic marker for early detection of RA [27] and several parameters of RA disease activity and severity was found to be significantly lower in those patients who have high levels of anti-IL-1α autoantibodies in comparison to those who have low levels of these autoantibodies. Autoantibodies

for monitoring the disease [19].

**2.1. Anti-cytokine autoantibodies**

**2. Different types of autoantibodies**

Several autoimmune diseases show chronic conditions that develop over the period of years and are characterized by the production of autoantibodies that actually present much before the actual onset of the disease. These autoantibodies are called as predictive autoantibodies that are present (or appear) in the blood much before systemic pathological conditions arise during the course of the disease. Detection of specific autoantibodies is the most important clinical and experimental evidence to predict any autoantibodies as biomarker for that autoimmune disease [11]. The levels and variety of autoantibodies may vary according to the disease that may function as predictive biomarker. While the experimental importance of autoantibodies has been well recognized in many clinical conditions, its clinical utilization remains to be short for most of the diseases [12]. Autoimmune diseases are caused by various autoimmune responses, generated during the course of the disease. The generations of immune responses are characterized by the appearance of the autoantibodies in the serum, therefore recognition of a particular autoantibody showed the path to recognize an autoimmune disease. Initially, the clinical symptoms of the disease are not emerges in full flash although these autoantibodies may arises much before these symptoms and actual onset of the disease. So, the symptoms are not visible, so the physician did not think to test these autoantibodies initially [13]. Therefore, test for these autoantibodies could be done in prescreening on various groups of population to identify the individuals who are susceptible for the development of the disease at an early stages and treatment should be given to prevent the actual occurrence of the disease. Multiple tests have been given for these patients for different autoimmune diseases, and recommendations are given to done multiple test for the patient who are having autoimmune disease [14]. However, disease related autoantibodies cannot develop simultaneously, although they are present much before the actual disease onset, and many of these autoantibodies are antigen specific, so using a panel of different autoantibodies set, might helpful to increase the sensitivity and prediction of the test [15].

Autoimmunity arises due to the failure of the immune system to be self-tolerance, which is mediated through the involvement of T and B cells [16]. Most of the autoimmune disease involves T cell, which play an important role in dysregulation and autoimmune aggression and during this process large amount of autoantibodies are also produced. These autoantibodies plays not only in key pathogenic role in some diseases including SLE and Graves' disease but also found in some disease in which they play minor pathogenic role and can act as important biomarker [17, 18]. Cytokines, in addition to the production of autoantibodies, play important role in the generation of autoimmune response (especially pro-inflammatory cytokines: except multiple sclerosis), they are produced in response to the viral invasion and are deeply involved in various autoimmune process. Under normal condition, anti-cytokine antibodies response have been develop in healthy normal individual that is consider to be normal physiological process to control various immune response. These responses are for limited time initially, and then the concentration of these autoantibodies increases, reaching a threshold and then coming up to its normal concentration after few weeks. This process also occurs in some pathological conditions including autoimmunity and autoantibodies develop as a result of these processes might be used as prognostic marker for monitoring the disease [19].
