Recurrent Infections and the Immune System
The human immune system is a complex network of cells and proteins which act together to fight infections caused by bacteria, viruses, and parasites. They include:
• T-cells (white blood cells important in regulating the immune system and in helping fight viral infections).
• B-cells (cells that make specific proteins called antibodies or immunoglobulins to protect us from bacteria that cause ear infections, pneumonia, etc.)
• Phagocytes (cells that ingest foreign bodies and bacteria to kill them).
• Complement (proteins that help kill bacteria that may cause infection).
Children with immune system deficiencies either have few antibodies or the ones they have don’t function properly. They often have recurrent ear and/or sinus infections and may have had several bouts of bronchitis or pneumonia, infections that are certainly serious but rarely life-threatening. They may have had one or more sets of ear tubes, a tonsillectomy and adenoidectomy, and possibly even sinus surgery. Often the child is well while on antibiotics, but gets sick a few days after discontinuing the antibiotics. Children between 18 months and 5 years are most likely to suffer from recurrent infections.
Children are born with all three antibodies (IGG, IGA, and IGM). Because our immune system can’t make the most important antibody, IGG, in sufficient quantity until about six months, the baby is protected by IGG antibodies passed on by its mother before birth. If the baby’s own immune system doesn’t mature at the right time, the child may start a cycle of infections. This is often called “Transient Hypogammaglobulinemia of Infancy,” transient because the child will outgrow it, usually by age two or three, and Hypogammaglobulinemia because the IGG levels are low.
A doctor who suspects immune system problems may schedule several blood tests, possibly a complete blood count as well as tests that measure the number of antibodies present and tests to determine how well they function. The functional tests may include a tetanus titer, drawn to see if the child has responded normally to DPT immunizations. Another test measures the child’s response to a vaccine called Pneumovax, which is often used to protect the elderly against pneumonia. The vaccine itself is very safe. Side effects, such as local swelling or low-grade fevers, are uncommon. Blood drawn before the vaccine is given is compared to blood drawn a month later. Normal immunoglobulin levels in a child who doesn’t respond appropriately to the vaccinations suggests that the immune system isn’t functioning properly.
Once a child is diagnosed with an Antibody Deficiency Syndrome, the first line of therapy is to clear up any existing infections, usually with antibiotics taken as long as four to six weeks. Once the child is free of infection, one strategy is to treat with a preventative antibiotic. These antibiotics, often taken as a lower dose than the initial treatment dose, are generally taken once a day to help prevent further infections from developing but there is often a concern that resistance to the antibiotic could develop. The antibiotics reduce the frequency of infections for about 75% of the children who take them.
The 25% of children who continue with recurrent infections are often treated with intravenous immunoglobulin (IVIG). IVIG is a preparation of Immunoglobulin G (IGG) antibodies that replace the antibodies which are not present or not working properly. IVIG is given by infusion into a vein. The infusion is generally well tolerated and takes approximately 2 to 4 hours. IVIG is usually given during the fall and winter months when infections are most common, and may be stopped during the summer. Some children, however, may require the IVIG year round.
Most of these conditions are self-limited. When children outgrow the immune deficiency, as they usually do, the preventative antibiotic or IVIG can be discontinued.
Common Variable Immunodeficiency (CVID)
What Is It?
Common variable immunodeficiency is characterized by unusual infections and low levels of serum immunoglobulins. The particular type of antibody deficiency (IGG alone, both IGG and IGA, or IGG, IGA and IGM together) can vary from patient to patient. Not only does the disorder range from severe to mild, but it can also develop at any time, during infancy and childhood, during or after puberty, or even during the third or fourth decades of life. Tests may not only show markedly decreased antibodies, but also impaired antibody responses. They can help your doctor decide if you can benefit from immunoglobulin infusions (IVIG).
The cause is largely unknown. We know that it isn’t caused by a single defect: the B-lymphocytes may be either absent or reduced, the helper T-lymphocytes may be deficient or the suppressor T-lymphocytes may be excessive. Unlike X-linked agammaglobulinemia, common variable immunodeficiency is not inherited in a single, well-defined pattern. More than one member of some families may be affected, while there is no link in others. Both males and females can develop the disease.
Your first symptoms are likely to be recurrent bacterial infections involving the ears, sinuses, nose, bronchi and lungs. If your infections are severe enough and recur often enough, you can permanently damage the bronchial tree. One of the dangers here is bronchiectasis, a chronic disease that inflames the breathing tubes, eventually widening and scarring them. A morning cough that produces yellow or green sputum may point to bronchiectasis. Bacteria (Hemophilus influenza, pneumococci and staphylococci) that are wide-spread in the general population may cause pneumonia.
Not only do patients with CVID have a depressed antibody response and low levels of antibody in their blood (hypogammaglobulinemia), but the antibodies that they produce may also attack some of their own tissues. These autoantibodies may attack and destroy red blood cells, white blood cells or platelets, and may cause other disorders as well. Gastrointestinal complaints, such as abdominal pain, bloating, nausea, vomiting, diarrhea and weight loss are quite common. Digestive problems can result in malabsorption of fats and certain sugars or from infection with Giardia lamblia, a small parasite. Giardia can be found in a stool sample or biopsy. Eliminating the parasites with medication may take care of your digestive symptoms.
Unless you have already developed complications, you are unlikely to have any physical abnormalities. Lymphoid tissue such as tonsils and lymph glands may be small or barely identifiable. Some patients can have an enlarged spleen and lymph nodes. If chronic lung disease has developed, patients may have an underdeveloped chest and decreased vital capacity, i.e. the maximum amount of air you can take into the lung voluntarily.
Common variable immunodeficiency may be suspected in children and adults who have a history of recurrent infections involving ears, sinuses, bronchi and lungs. The diagnosis is confirmed by finding a low level of serum immunoglobulins, usually including IGG, IGA and IGM. The latter two immunoglobulin classes may be completely absent in some patients or near normal in others. Patients who have received complete immunizations against polio, measles, diphtheria and tetanus will have very low or absent antibody levels to these microorganisms
The purpose of treatment is prevention. Your doctor will try to control recurrent lung infections and the accompanying damage to lung tissue. Immunoglobulin infusions (IVIG) almost always help. IV IG is a blood product made from pooled plasma from many donors. There is no risk of HIV infections. Precautions have been taken to reduce the risk of Hepatitis.
If you have chronic sinusitis or chronic lung disease, you may need long-term treatment with broad spectrum antibiotics. If you already have bronchiectasis, you may need physical therapy and daily postural drainage to remove secretions and pus from your lungs and bronchi.
IVIG and antibiotics have greatly improved the outlook of patients with common variable immunodeficiency. Our aim is to keep you from getting infections and to prevent chronic lung disease. To some extent the outlook depends on how much damage to your lungs and other organs has already occurred, and how successfully IVIG can prevent future infections.
Selective IGA Deficiency
The body defends itself from infection with antibodies (immunoglobulins). An antibody known as IGA protects the mucous membranes (the mouth and nose, the lungs, the throat, the gastrointestinal tract, the eyes and the genitalia).
Selective IGA deficiency is the total absence or severe deficiency of IGA. B-lymphocytes are present there but are unable to change into the IGA-producing plasma cells. Because all the other antibodies are normal or near-normal, the condition is called selective IGA deficiency. The causes are still unknown, and may vary from patient to patient.
IGA deficiency is the most common of the immunodeficiency diseases: studies indicate that as many as one in every five hundred people has the condition. Many of them are relatively healthy and free of symptoms. Because they aren’t sick enough to go to the doctor, their IGA deficiency is unrecognized.
Although we still don’t understand why some people with IGA deficiency have almost no illnesses while others are sick, some studies suggest that some patients with IGA deficiency may be missing a fraction of another antibody (IGG) subclass. This may explain why some patients with IGA deficiency are more susceptible to infection than others.
Many who have IGA deficiency also have allergies and recurrent infections. Because your mucous membranes are virtually unprotected, you are likely to have a history of ear infections, sinusitis and pneumonia. And because these infections are persistent, you may have to remain on antibiotics longer than usual. If your blood contains no IGA, the body recognizes IGA as a foreign protein, which can cause a massive allergic reaction if you receive a blood transfusion that contains IGA. If you have Selective IGA Deficiency, it’s important to recognize the potential risk in a blood transfusion. You should use IGA deficient blood products and wear a medic alert bracelet to let others know in an emergency that you have special needs.
IGA deficiency is usually first suspected because of either chronic or severe recurrent infections, allergies, autoimmune diseases, or chronic diarrhea. If your doctors suspect IGA deficiency, they will probably schedule a complete blood count and immunoglobulins levels. Other tests may be indicated if autoimmune disease is suspected.
Unfortunately, it isn’t possible to replace IGA in IGA-deficient patients; the available gamma globulin simply doesn’t contain enough IGA. Even if it were available, there is no way that IGA administered by infusion into the vein can find its way to the mucous membranes where it is needed. Doctors treat the illness associated with IGA deficiency instead of the condition itself. If you have chronic or recurrent infections, antibiotics are the treatment of choice. If possible, they direct the antibiotic at the specific organism causing you infection; generally broad spectrum antibiotics are used to cover the bacteria that typically cause the infection. You may need long-term therapy with antibiotics if you have chronic sinusitis or chronic bronchitis. Physicians treat allergies associated with IGA deficiency with the same treatments they use for allergies in general, although they may have to pursue them more aggressively.
Although selective IGA efficiency is one of the milder forms of immune deficiency, it can result in a severe disease in some people. It is difficult to predict the long term outcome in a given patient-the prognosis depends on the prognosis of the associated disease. It’s vital for your doctor to continually assess and reevaluate your health. In some children, IGA deficiency eventually can resolve, with normal levels developing later in childhood. The most important aspect of therapy in IGA deficiency, as it is in all immunodeficiency diseases, is close communication with your physician. Problems need to be treated as soon as they arise.
Adapted from the Immune Deficiency Foundation Family Handbook
If you need more information, please feel free to contact us at:
The Atlanta Allergy & Asthma Clinic
1965 North Park Place, NW, Atlanta, Georgia 30339.