Immune-Mediated Disease
المؤلف:
Mary Louise Turgeon
المصدر:
Immunology & Serology in Laboratory Medicine
الجزء والصفحة:
5th E, P71-72
2025-07-02
517
The immune system is normally efficient in eliminating foreign antigens. The nature of the antigen or the genetic makeup of the host, however, can cause alterations of the immune response that can be injurious and lead to immune-mediated disease (Table 1). In these disorders, the immune response is normal but the reactivity is heightened, prolonged, or inappropriate.
Table1. Immune-Mediated Disease
A major concern is allergic reactions, characterized by an immediate response on exposure to an offending antigen and the release of mediators (e.g., histamine, leukotrienes, prostaglandins) capable of initiating signs and symptoms (see Chapter 26). Although allergic reactions are associated with IgE, not all allergic reactions are IgE-mediated. Complement activation by immune complexes or through the alternative complement path way has been shown to release complement C3a and C5a ana phylatoxins, which are capable of producing similar reactions.
Autoimmune disease is thought to be caused by antibody or T cell sensitization with autologous self-antigens. Postulated mechanisms of this process include the following:
• Altered antigen or neoantigen. These antigens may be created by chemical, physical, or biologic processes. Hemolytic anemia caused by a drug interaction is an example of this process occurring in RBCs.
• Shared or cross-reactive antigens. Evidence has suggested that poststreptococcal disease occurs through this mechanism.
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