Total absence or severe deficiency of immunoglobulin (Ig) A, also known as Janeway Type 3 dysgammaglobulinemia, is the most common primary immunoglobulin deficiency, appearing in as many as 1 in 400 to 1,000 people. IgA — the major immunoglobulin in human saliva, nasal and bronchial fluids, and intestinal secretions — guards against bacterial and viral reinfections. Consequently, IgA deficiency leads to chronic sinopulmonary infections, allergies, chronic diarrhea, GI diseases, and other disorders. The prognosis is good for patients who receive correct treatment, especially if they have no associated disorders.
IgA deficiency seems to be linked to autosomal dominant or recessive inheritance. The disorder has familial trends and occurs frequently in immediate relatives of individuals with common variable immunodeficiency. The presence of normal numbers of peripheral blood lymphocytes carrying IgA receptors and of normal amounts of other immunoglobulins suggests that B cells may not be secreting IgA, as they haven’t matured into IgA-producing plasma cells. Congenital intrauterine infection with rubella, toxoplasmosis, or cytomegalovirus can result in selective IgA deficiency. Treatment for seizures with phenytoin and hydantoin, as well as Wilson disease (an inherited disorder treated with penicillamine), can result in temporarily acquired selective IgA deficiency. When the medications are stopped, the IgA level returns to normal. Some drugs such as anticonvulsants may cause transient IgA deficiency.
Some IgA-deficient patients have no symptoms, possibly because they have extra amounts of low-molecular-weight IgM. This immunoglobulin takes over IgA function and helps maintain immunologic defenses. Among patients who develop symptoms, chronic sinopulmonary infection is the most common. Other effects are respiratory allergy, often triggered by infection; GI tract diseases, such as celiac disease, ulcerative colitis, and regional enteritis; autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus, immunohemolytic anemia, and chronic hepatitis; and malignant tumors, such as squamous cell carcinoma of the lungs, reticulum cell sarcoma, and thymoma.
Age of onset varies. Some IgA-deficient children with recurrent respiratory disease and middle ear inflammation may begin to synthesize IgA spontaneously as recurrent infections subside and their condition improves.
Serum immunoelectrophoresis and quantitative immunologic analyses of patients with IgA-deficiency show serum IgA levels below 7 mg/dl. Although IgA is usually absent from secretions in patients with IgA-deficiency, levels may be normal in rare cases. IgE is normal, whereas IgM may be normal or elevated in serum and secretions. Normally absent low-molecular-weight IgM may be present.
Tests may also indicate autoantibodies and antibodies against IgG (rheumatoid factor), IgM, and bovine milk. Cell-mediated immunity and secretory piece (the glycopeptide that transports IgA) are usually normal, and most circulating B cells appear normal.
Selective IgA deficiency has no known cure. Treatment aims to control symptoms of associated diseases, such as respiratory and GI infections, and is generally the same as for a patient with normal IgA.
If transfusion with blood products is necessary, minimize the risk of adverse reaction by using washed red blood cells or avoid the reaction completely by crossmatching the patient’s blood with that of an IgA-deficient donor.
Because this is a lifelong disorder, teach the patient to prevent infection, to recognize its early signs, and to seek treatment promptly.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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Title: Professional Guide to Diseases (Eighth Edition)
Authors: Springhouse
Publisher: Lippincott Williams & Wilkins
Copyright: 2005
ISBN: 1-58255-370-X
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