Over the last few months, Dr. Weiss has seen two patients that are newly diagnosed with IgA deficiency. Selective IgA deficiency is the most common of the immunodeficiency disorders. Some studies find that as many as one in 500 people have this disorder.
It is primarily the IgA 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, and agglutinate bacteria, as well as bind various food antigens.
IgA is produced by B-lymphocytes, but in IgA deficiency, the B cells are unable to change 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; however, 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.
A recent issue in JAMA (Jan. 7, 1998 Vol 279, No.1) highlighted the inclusion of immunodeficiency in the differential diagnosis of recurrent infections in both adults and children. Many physicians are vigilant for immunodeficiency in childhood due to the more common presentation during this time.
This article notes that consideration needs to be employed for adults as well due to some of the immunodeficiencies presenting in later years. This includes diseases such as Common Variable Immunodeficiency, IgA deficiency, and complement deficiency.