Primary Immunodeficiency (PI) : Treatments, Part 3

by National Institute of Health

(Page 7 of 13)

Boys with XLA are also susceptible to viruses that are normally neutralized by antibodies during their spread in the bloodstream. These include common viruses that cause diarrhea as well as viruses that cause liver disease (hepatitis) and polio. (An XLA child who receives oral polio vaccine risks paralysis.)

Laboratory tests show extremely low levels of B cells, especially the mature B cells capable of secreting immunoglobulins. Overall immunoglobulin levels in the blood are low, and specific antibodies - for instance, to any vaccines the child has received - are missing. Tissues rich in B cells such as tonsils and lymph nodes may be undersized or scanty.

Although XLA cannot be cured, it can be controlled with immunoglobulin therapy. Large doses of immune globulins, taken regularly for life, will prevent most infections. For the most part, these children will be able to live relatively normal and active lives.

Common Variable Immunodeficiency (CVID) is the name given to a group of disorders characterized by low levels of gammaglobulins and too few IgA antibodies. People with CVID may have normal numbers of B cells, but their B cells don't function properly. Their T cells also show a variety of defects.

This disease - also known as hypogammaglobulinemia (hypo = low, gammaglobulin = antibodies, emia = in the blood) - can occur in children, but it is more common in people in their twenties or thirties. It affects both men and women. Most patients have no family history of CVID, but they may have relatives with Selective IgA Deficiency.

Like most antibody deficiencies, CVID causes frequent bacterial infections, typically involving the ears, sinuses, and airways. Many CVID patients experience several bouts of pneumonia and some develop infections in joints, bones, and skin.

About a quarter of the people with CVID develop immune system illnesses, including anemia and rheumatoid arthritis. They also have an increased risk of cancer.

Disorders of the digestive tract are common. In addition to diarrhea caused by Giardia parasites, people with CVID are prone to inflammatory bowel diseases such as ulcerative colitis, or even colon cancer. Many have an enlarged spleen and swollen lymph glands, and some develop lymph system cancer (lymphoma).

Tests helpful in diagnosing CVID include measures of IgG and IgA levels in the blood and measures of antibody responses to immunizations.

Although antibiotics will help to control infections, the cornerstone of treatment is gammaglobulin therapy. Gammaglobulins will raise antibody levels and fend off infections, allowing many persons with CVID to enjoy a normal lifestyle.

Hyper-IgM Syndrome youngsters often have high levels of IgM, the early-response antibody. However, they have no IgA, the class of antibody found in body fluids such as saliva, mucus, and tears, and they have very low levels of IgG, the common immunoglobulin in the blood. They also may have very low levels of the infection-fighting white blood cells called neutrophils.

The underlying problem in one form of Hyper-IgM involves T cells. In the X-linked form of Hyper-IgM Syndrome, the faulty gene fails to encode a molecule that normally permits T cells to communicate with B cells. B cells making IgM fail to get a signal from T cells, telling them to switch to making IgA and IgG.

Sometime before their first birthday, children with Hyper-IgM Syndrome begin to contract bacterial infections - ear infections, sinus infections, pneumonia, and tonsillitis. Many develop sores inside their mouths. In addition, they are susceptible to opportunistic infections, especially Pneumocystis pneumonia.

Another aspect of Hyper-IgM Syndrome is autoimmune disease. Autoimmune attacks on red blood cells lead to anemia, while autoimmune destruction of infection-fighting neutrophils further increases the risk of infection.

Many youngsters with Hyper-IgM Syndrome respond well to treatment, become symptom-free and resume normal growth. The cornerstone of treatment is regular IVIG, which not only supplies missing IgG antibodies, but also prompts a drop in IgM antibodies.

Selective IgA Deficiency is characterized by a deficiency of immunoglobulins in body secretions and the mucous membranes lining the airways and digestive tract. IgA normally stands guard at the body entrances, intercepting bacteria, viruses, toxins, and certain food components.

IgA Deficiency is the most common of the PIs. Studies of blood samples from blood bank donors show that IgA Deficiency occurs in as many as 1 of every 333 Americans with a Caucasian background.

Although this makes IgA Deficiency more common than all other immunodeficiencies combined, most people never know they have it. They remain healthy, with no more than the usual number of infections. Others suffer through more than their share of infections without ever knowing why.

When IgA Deficiency is diagnosed, it is usually because of an increase in the number of ear, sinus, and lung infections that are slow to respond to standard antibiotics. Treatment consists mainly of antibiotics, for specific infections and to prevent infections from becoming chronic.

About the Author

NIH is the nation's medical research agency - making important medical discoveries that improve health and save lives. The National Institutes of Health (NIH), a part of the U.S. Department of Health and Human Services, is the primary Federal agency for conducting and supporting medical research.