Immune thrombocytopenic purpura and intravenous immunoglobulin

Article Abstract:

Idiopathic thrombocytopenic purpura is a bleeding disorder that results from the increased destruction of platelets, the cell fragments in the blood which initiate blood clotting. The production of platelets in patients with ITP is not affected. ITP is now recognized as an autoimmune disorder, and some clinicians have suggested the disorder now be referred to as immune or autoimmune thrombocytopenic purpura rather than idiopathic. Intravenous immunoglobulin (IVIG) therapy has proved effective in the treatment of ITP, but the mechanisms of action of IVIG are still under investigation. Understanding the physiological mechanisms is important, since it may permit the successful application of IVIG to a broader range of autoimmune disorders. One possible mechanism of action is that the injected immunoglobulins interfere with Fc receptors on phagocytes. Under normal conditions, antibodies cover foreign organisms. Phagocytes have receptors for the Fc portion of antibody molecules; recognizing the Fc portion of the antibodies covering the bacteria, they engulf and consume the offending organism. Under pathological conditions, the same phagocytes may consume the needed platelets. IVIG may interfere with the recognition of the Fc region of antibody molecules and therefore interfere with the phagocytosis of platelets. A second physiological mechanism that may ultimately be found to be important is the alteration of the idiotype-anti-idiotype network. In addition to recognizing antigens, antibodies may serve as antigens themselves. The part of an antibody that is recognized by other antibodies is called the idiotype; the antibodies that recognize the idiotype are called anti-idiotypic. It is thought that the amounts of various antibodies in the body are closely regulated by anti-idiotypic antibodies, and that some autoimmune disorders may arise from an abnormality in this control. Intravenous immunoglobulin contains a wide variety of different antibodies, including many anti-idiotypic antibodies. These antibodies, purified from the blood of many healthy donors, may contain just the anti-idiotypic antibodies necessary to rein in an abnormal antibody response of the patient with thrombocytopenic purpura. (Consumer Summary produced by Reliance Medical Information, Inc.)

Usage, Thrombocytopenic purpura

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Use of intravenous immunoglobulin in various medical conditions: a Japanese experience

Article Abstract:

Intravenous immunoglobulin (IVIG) therapy is finding increasing use in medical treatment. Antibodies, obtained from pooled donor blood, can now be purified to make them suitable for intravenous injection. These antibodies may then be used to supplement the antibodies in the blood of patients with immune deficiencies, as well as to compensate for immune abnormalities in patients with autoimmune diseases. Among the disorders for which IVIG is receiving attention as a possible treatment is Kawasaki disease. Endemic in Japan and familiar in the United States, Kawasaki disease affects infants and children. The young patients suffer fluid accumulation and tissue damage in their hands and feet, inflammation of mucous membranes and skin, and a host of other symptoms. Children with Kawasaki disease may rapidly develop lesions in the coronary arteries serving the heart. From 20 to 40 percent may develop such artery lesions, which can include the formation of aneurysms, blood-filled pathological pockets on a coronary artery. These lesions may contribute to the clotting of blood within the artery and the occlusion of blood flow to the heart. In one study of children with Kawasaki disease, 15 percent of patients receiving both aspirin and IVIG developed coronary artery lesions within 30 days of the onset of Kawasaki symptoms. In contrast, 42 percent of the patients treated with aspirin alone developed coronary artery lesions within the same period. Children treated with IVIG were also more likely to remain free of persistent lesions. Three of 40, or 7.5 percent, of the IVIG-treated children had persistent lesions 30 days after the start of treatment, while 31 percent of the children treated with aspirin only suffered from persistent lesions. (Consumer Summary produced by Reliance Medical Information, Inc.)

Kawasaki disease, Kawasaki syndrome

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Mechanisms of action of intravenous immunoglobulin therapy and potential use in autoimmune connective tissue diseases

Article Abstract:

The use of antibodies prepared from human blood donors in the treatment of disease dates back one century. However, 10 years ago it was found that intravenous immunoglobulins were successful in the treatment of thrombocytopenic purpura, an autoimmune disorder. This finding sparked renewed interest in the possible therapeutic use of immunoglobulins. Other autoimmune disorders such as systemic lupus erythematosus (SLE) may prove amenable to treatment with intravenous immunoglobulins (IVIG). Thus far, however, the only reports of the treatment of SLE with IVIG have been anecdotal, and therefore no firm conclusions can be drawn about this application of IVIG. Nevertheless, several reported cases indicate that some forms of SLE might yield to immunoglobulin therapy. Some patients with cytopenias (reduction in the number of certain blood cells) may be among the better candidates for IVIG, as may patients with inflammation of the blood vessels in the skin. However, patients should be treated cautiously. Patients with SLE may be suffering from impaired kidney function. Indeed, this is one of the serious potential complications of this disorder. Since IVIG may impair kidney function as well, IVIG should be used cautiously in patients with SLE. (Consumer Summary produced by Reliance Medical Information, Inc.)

Systemic lupus erythematosus, Gamma globulins

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