ABSTRACT
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Autoimmunity is defi ned as the immune response to antigens of the host itself. This autoimmune response can be demonstrated by the presence of circulating autoantibodies or T lymphocytes reactive with host antigens. A great deal of basic research has been dedicated to unraveling the mechanisms responsible for the body’s ability
to distinguish its own molecules from foreign molecules (see Chapter 1). Nevertheless, exceptions to the rules of governing self-/non-self-discrimination are well known. Most autoimmune responses do not result in disease, but when a harmful response occurs, the pathological consequence of the autoimmune response is called autoimmune disease. These disorders can affect virtually any site in the body so that their clinical presentation varies widely. In at least 80 diseases, autoimmunity is now recognized as an important cause or contributor. The immunologic diagnosis of autoimmune disease relies mainly on the demonstration of autoantibodies in the patient’s serum. This chapter describes the general approach to diagnosis, emphasizing both the uses and abuses of most widely used test procedures.
