Autoantibodies as predictors of disease

Autoimmune diseasesActivation of the immune response is a major feature of many disease processes.Immune responses can be protective, as in infectious diseases, or destructive, as in autoimmune inflammatory diseases, or both.The immune response usually involves activation of both T and B cells, the latter producing antibodies that can be detected in the sera and can be used to guide the clinical management of certain diseases.Here, we focus on autoantibodies as predictive markers of disease.While the practical value of autoantibodies has been realized in some clinical conditions, it remains underutilized in the majority of diseases.Recognizing the clinical potential of autoantibodies and identifying appropriate populations to screen for such autoantibodies, we argue, could have rich practical rewards. Autoantibodies as markers of disease activity and severityAntibodies may reflect the presence, nature, and intensity of the immune response.Since in autoimmune diseases the immune response is itself part of the disease process, it is possible to use autoantibodies as markers of disease activity.Autoantibodies can be detected in diseases with a long prodrome during which there are no clinical symptoms.In some of these diseases autoantibodies can predict both the likelihood of clinical disease and the rate of progression to disease, that is, the disease activity.In organ-specific autoimmune diseases such as type 1 diabetes and thyroiditis, autoantibodies can be detected in peripheral blood years before the destruction of hormone-secreting cells leads to overt clinical symptoms.Hence, many such autoimmune diseases are long-term and chronic in nature (1, 2).A variety of studies have now shown a direct relationship between the titer of the autoantibodies and the severity of the disease (1-3). Autoantibodies as markers to define and classify diseaseIn patients with established disease, autoantibodies can help define the nature of the disease and provide mark-ers to classify the disease.For example, type 1 diabetes, thyroiditis, and adrenalitis are classified as autoimmune or not autoimmune, based on the presence or absence of disease-associated antibodies.Similarly, there are several causes of atrophic gastritis and of vitamin B12 deficiency, but the combination of the two, in association with autoantibodies to parietal cells or intrinsic factor, indicates that the cause is autoimmune gastritis, also called pernicious anemia (PA) (4).