IgA deficiency is an IgA level < 10 mg/dL with normal IgG and IgM levels. It is the most common primary immunodeficiency. Many patients are asymptomatic, but some develop recurrent infections and autoimmune disorders. Diagnosis is by measuring serum Ig. Some patients develop common variable immunodeficiency, and some remit spontaneously. Treatment is avoidance of blood products that contain IgA; antibiotics are given as needed. Biology of the Immune System: Human Leukocyte Antigen (HLA) System
) region are common. IgA deficiency also occurs in siblings of children with common variable immunodeficiency (CVID) and evolves into CVID in some patients. Drugs such as Click for Drug Monograph
, Click for Drug Monograph
, colloidal gold and d-Click for Drug Monograph
may lead to IgA deficiency in genetically susceptible patients.
Symptoms, Signs, and Diagnosis
Many patients are asymptomatic; others have recurrent sinopulmonary infections, diarrhea, allergies, or autoimmune disorders (eg, celiac or inflammatory bowel disease, SLE, chronic active hepatitis). Anti-IgA antibodies may develop after exposure to IgA in plasma or to immune globulin; anaphylactic reactions to IV immune globulin (IVIG) and other blood products that contain IgA may occur.
Diagnosis is suspected in patients who have recurrent infections (including giardiasis); anaphylactic transfusion reactions; or a family history of CVID, IgA deficiency, or autoimmune disorders or who are taking drugs that lead to IgA deficiency. Diagnosis is confirmed by a serum IgA level < 10 mg/dL with normal IgG and IgM levels and normal antibody titers in response to vaccine antigens.
Prognosis and Treatment
A few IgA-deficient patients develop CVID over time; others improve spontaneously. Prognosis is worse if an autoimmune disorder develops.
Treatment is avoidance of blood products that contain IgA because even trace amounts can elicit an anti-IgA–mediated anaphylactic reaction. If RBC transfusion is needed, only washed RBCs or frozen blood can be used. Antibiotics are given as needed for bacterial infections of the ears, sinuses, lungs, or GI or GU tract. IVIG is contraindicated because many patients have antibodies to IgA and because IVIG is > 99% IgG, which patients do not need. Patients are advised to wear an identification bracelet to prevent inadvertent plasma or IVIG administration, which could lead to anaphylaxis.