3Celiac disease (CD) is an autoimmune disorder induced by gluten intake in genetically susceptible individuals. It is characterized by the presence of serum antibodies to endomysium, reticulin, gliadin, and tissue transglutaminase. The incidence of CD in various autoimmune disorders is increased 10-to 30-fold in comparison to the general population, although in many cases CD is clinically asymptomatic or silent. The identification of such cases with CD is important since it may help in the control of type I diabetes or endocrine functions in general, as well as in the prevention of long-term complications of CD, such as lymphoma. It is believed that CD may predispose an individual to other autoimmune disorders such as type I diabetes, autoimmune thyroid, and other endocrine diseases and that gluten may be a possible trigger. The onset of type I diabetes at an early age in patients with CD, compared to non-CD, and the prevention or delay in onset of diabetes by gluten-free diet in genetically predisposed individuals substantiates this antigen trigger hypothesis. Early identification of CD patients in highly susceptible population may result in the treatment of subclinical CD and improved control of associated disorders.Autoimmunity as a concept evolved from the beginning of this century, when Ehrlich and Morgenroth (26) introduced the phenomenon of "horror autotoxicus," i.e., fear of selfpoisoning. Subsequently, many diseases were recognized with etiology arising from the abnormal reaction of the immune system to self antigens. These observations laid the foundation for establishing postulates that are characteristic of an autoimmune disease (4, 7). Since then, several hypotheses have been put forward regarding the mechanisms of autoimmunity (22,76,84,110,118).In general, autoimmune disorders can be classified as either organ specific or non-organ specific. In organ-specific autoimmune diseases, the autoantibodies are specifically directed against antigens localized in a particular organ and are often detected in circulation. Examples of organ-specific autoimmunity include Hashimoto's thyroiditis, type I diabetes, and myasthenia gravis.In contrast, the non-organ-specific autoimmune disorders are characterized by the presence of autoantibodies directed against ubiquitous antigens (not specific to a particular organ). This results in the involvement of several organs and is often characterized by the presence of specific circulating immune complexes. Non-organ-specific autoimmunity includes diseases such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and scleroderma.Epidemiologic studies have shown that genetic factors are involved in host susceptibility to autoimmune disease. For example, the concordance rate of a particular autoimmune diseases is much higher in monozygotic twins in comparison to fraternal twins (17). Moreover, this incidence is much higher in organ-specific autoimmune disorders in comparison to nonorgan-specific disorders. Thus, in Grave's thyrotoxicosis, Hashimoto's disease, a...
