IgA deficiency

Over the last few months I have seen 2 patients newly diagnosed with IgA deficiency. Selective IgA Deficiency is the most common of the immunodeficiency disorders. Some studies site as many as 1:500 people have this disorder. It is primarily the Ig A antibody that is transported to secretions to protect the body’s mucosal surfaces from infection. These mucosal surfaces include the sinopulmonary, genital and gastrointestinal tracts. Secretory IgA can neutralize viruses, bind toxins, agglutinate bacteria, and bind various food antigens. IgA is produced by B-lymphocytes, but in IgA deficiency, the B cells are unable to changed into IgA producing plasma cells. The underlying defect for this lack of differentiation is still unclear.

There are a large number of people with IgA deficiency who are symptom free, but then there are others who come to our attention due to recurrent infections, food allergies , autoimmune disease, and anaphylaxis due to blood transfusions. The kinds of infections that are seen in patients with IgA deficiency include sinusitis, otitis media, pneumonia and parasitic such as Giardia. Other immunodeficiencies may be associated with IgA deficiency such as IgG subclass deficiencies and Common Variable Immunodeficiency.

Evaluation of IgA deficiency first requires a high index of suspicion. Based on your clinical gestalt, the patient who is an outlier with respect to recurrent infections or with autoimmune disease, is a candidate for quantitative immunoglobulins: IgG, IgA, IgM and IgE. (cost about $100) When evaluating a child for IgA deficiency, the blood results need to be compared to age appropriate values. Many children have transient IgA deficiency secondary to immaturity of their immune system. There also acquired forms of IgA deficiency due to the use of certain medications such as penicillamine, sulfasalazine, valproate, hydantoin and captopril. These drugs usually cause a reversible deficiency.

There is no specific treatment for IgA deficiency. Intermittent or continuous prophylactic antibiotics may be helpful for recurrent infections. Some patients may be candidates for Intravenous Immunoglobulin. Patients need to be aware that they may be at risk for reactions with improper blood transfusions. Many immunologists recommend testing for antibodies against IgA and if there are antibodies, the patient should wear a Medi-Alert bracelet. The prognosis is variable for IgA deficient patients. It is important for physicians to continually assess and reevaluate for the development of associated disease.