Common variable immunodeficiency
Description, Causes and Risk Factors:
Alternative Name: Acquired hypogammaglobulinemia, adult onset hypogammaglobulinemia.
CVID is a group of rare genetic (primary) immunodeficiency disorders in which abnormalities in immune cell development (maturation) result in a decreased ability to appropriately produce antibodies in response to invading microorganisms, toxins, or other foreign substances. The symptoms of Common variable immunodeficiency usually become apparent during the second to the fourth decade of life.
These disorders are caused by intrinsic or genetic defects in the immune system. Therefore, individuals who have primary immune deficiencies are born with the disorder.
The disorder is characterized by a lack of antibody producing B-cells or plasma cells, low levels of most or all types of immunoglobulin, and recurrent bacterial infections.
While the exact incidence of Common variable immunodeficiency is unknown, researchers estimate that about one out of 50,000 individuals develop the disorder.
Although decreased serum levels of immunoglobulin G (IgG) and immunoglobulin A (IgA) are characteristic of the disorder, about 50% of CVID patients also have decreased immunoglobulin M (IgM) levels. In addition, about half of CVID patients experience some T-lymphocyte dysfunction.
It is thought that Common variable immunodeficiency may result from a combination of genetic defects or from different disease genes (heterogenous). In many cases, there is no clear pattern of inheritance. However, in successive generations of some affected families (kindreds), there is evidence that CVID may be inherited as an autosomal recessive genetic trait. In addition, a rare acquired form of the disorder has been described in the medical literature. No clear pattern of inheritance has been observed. In most cases, there is no family history of immunodeficiency. However, when more than one family member is diagnosed with Common variable immunodeficiency, researchers believe it is the result of autosomal recessive inheritance.
In some cases, individuals with CVID have an increased tendency to develop certain diseases characterized by abnormal tissue growths (neoplasms) that may be benign or malignant. In addition, some individuals with CVID may have an unusual susceptibility to certain autoimmune diseases. These disorders occur when the body's natural defenses against invading microorganisms mistakenly attack healthy tissue. The range and severity of symptoms and findings associated with CVID may vary from case to case.
In general, the expected survival rate for male and female patients is 92% and 94%, respectively. Factors associated with fatality include low levels of IgG, poor T-cell responses to antigens, and a low percentage of B cells. Deaths related to Common variable immunodeficiency are usually the result of lymphoma. Other potential causes of death include right-sided heart failure secondary to chronic lung infection, liver failure, and malnutrition (resulting from gastrointestinal tract disease).
The first signs of the deficiency are recurrent bacterial infections, which may occur as early as infancy or as late as the fourth decade of life. Common symptoms include recurrent infections of the ears, bronchi, sinuses, and lungs. Bronchiectasis
(widening and scarring of the bronchial tubes) infections of the bronchi are severe. Patients with bronchiectasis may have a regular morning cough that produces yellow or green sputum. Many Common variable immunodeficiency patients have an enlarged spleen and lymph nodes. Other patients may develop painful inflammation of the knees, ankle, elbows, or wrist joints. Gastrointestinal symptoms may include abdominal pain, bloating, nausea, vomiting, diarrhea, or weight loss. Some patients develop autoantibodies, which are antibodies that mistakenly attack the body's tissues. Autoantibodies
can destroy one or more types of body tissues, cause abnormal organ growth, or impair organ function. Autoantibodies commonly affect blood components (like red blood cells, connective tissues, and blood vessels), endocrine glands (like the thyroid or pancreas), as well as muscles, joints, and the skin.
A nephelometry blood test may be performed to diagnose CVID. The disorder is diagnosed after significantly decreased IgG and IgA levels are observed in the patient's blood. Some patients may also have decreased IgM levels. During the procedure, a sample of blood is taken from the patient. Anti-immunoglobulins are added to the blood sample. A medical instrument then measures the movement of particles in a substance that is caused by the interaction between immunoglobulins and anti-immunoglobulins. The test quickly and accurately measures the amount of IgM, IgG, and IgA in the patient's blood. Healthy individuals have 100-400 milligrams of IgA per deciliter of blood, 560-1,800 milligrams of IgG per deciliter of blood, and 45-250 milligrams of IgM per deciliter blood.
While there is currently no cure for Common variable immunodeficiency, various treatments may help relieve symptoms and resolve infections associated with the disease. IVIG (intravenous immunoglobulin) therapy is used most often to treat CVID patients.
Immunoglobulin may be administered intravenously (injected into the vein) or subcutaneously (injected below the skin). Solutions of 3-12% intravenous immunoglobulin (IVIG) have been used on a regular basis to maintain a trough level of 400-500 milligrams/deciliter in adults. A dose of 400-600 milligrams/deciliter every two to four weeks is usually required. In patients with structural lung damage, a trough level of 700-800 milligrams/deciliter is generally required.
The most common side effects of IVIG include backache, nausea, vomiting, chills, low-grade fever, myalgia (general feeling of discomfort), and fatigue. Adverse effects usually occur within 30 minutes of the infusion and typically last for several hours. Slowing the rate of infusion or interrupting the infusion for a few minutes can help prevent side effects. Adverse effects can be treated with antipyretics, diphenhydramine, or corticosteroids. Although anaphylactic reactions to immunoglobulin concentrates are rare, patients who have IgA deficiency have an increased risk for these effects. Long-term intravenous access is not recommended because it can increase the risk of infection.
Patients with chronic sinusitis or lung disease may need long term treatment with broad spectrum antibiotics such as ampicillin (Principen®), tetracycline (Helidac Therapy®, Sumycin®, or Sumycin® Syrup), cephalexin (Biocef®, Keflex®, Keftab®, Panixine®, or Zartan®), trimethoprim/sulfmethoxazole (Bactrim® or Septra®), or ciprofloxacin (Cipro®).
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.