Cardiovascular Disorders
المؤلف:
Mary Louise Turgeon
المصدر:
Immunology & Serology in Laboratory Medicine
الجزء والصفحة:
5th E, P386-387
2025-09-17
205
The primary immunologic diseases of the blood vessels are termed vasculitis; those of the heart are termed carditis.
Vasculitis
Deposition of circulating immune complexes is considered directly or indirectly responsible for many forms of vasculitis. The inflammatory lesions of blood vessels produce variable injury or necrosis of the blood vessel wall. This may result in narrowing, occlusion, or thrombosis of the lumen or aneurysm formation or rupture. Vasculitis occurs as a primary disease process or as a secondary manifestation of another disease (e.g., RA).
Vasculitis is characterized by inflammation within blood vessels, which often results in a compromise of the vessel lumen with ischemia. Ischemia causes the major manifestations of the vasculitic syndromes and determines the prognosis. Any size and type of blood vessel may be involved. Therefore, the vasculitic syndromes are a heterogeneous group of diseases (Box 1).
Box1. Classification of Vasculitic Syndromes
Antibodies specific to endothelial cells also contribute to immune vasculopathy. Antiendothelial antibodies are autoantibodies directed against antigens in the cytoplasmic membrane of endothelial cells.
Carditis
The heart shares a susceptibility to immune-mediated injury with other organs. Numerous cardiac diseases are characterized by the presence of inflammatory cells within the myocardium resulting from immune sensitization to endogenous or exogenous cardiac antigens. The consequent reaction of cardiac myocytes to immune injury can range from reversible modulation of their electrical and mechanical capabilities to cell death. Carditis can be caused by a variety of conditions, including acute rheumatic fever, Lyme disease, and cardiac transplant rejection.
Myocardial contractility can be impaired by cell-mediated injury or the local release of cytokines. The study of immune cardiac disease has entered a period of rapid expansion. Primary idiopathic myocarditis is an autoimmune disease characterized by infiltration of the heart by macrophages and lymphocytes. Studies involving the mechanisms whereby immune cells and factors localize in the myocardium, modulate myocyte function, and remodel myocardial architecture are under way.
A diagnosis of acute rheumatic fever requires differentiation from other immunologic and infectious diseases. The immunologic basis for rheumatic heart disease has long been suspected. Patients with rheumatic heart disease exhibit antimyocardial antibodies that bind in vitro to foci in the myocardium and heart valves. These antibodies may be responsible for the deposition of immunoglobulin and complement components found in the same area of rheumatic heart disease tissues at autopsy.
Antimyocardial antibodies appear to be strongly cross reactive with streptococcal antigens, but they are not toxic to heart tissue unless the latter is damaged previously by some other cause. Because antimyocardial antibodies are often found in patients with a recent myocardial infarction or streptococcal infection without cardiac sequelae, detection of these antibodies has not been a particularly useful differential diagnostic test for cardiac injury. The presence of myocardial antibodies, however, is diagnostic of Dressler’s syndrome (cardiac injury) or rheumatic fever.
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