Common Variable Immunodeficiency - An Overview

Introduction:

Common variable immunodeficiency (CVID) is a condition that causes impairment of the immune system. It is one of the most commonly diagnosed primary immunodeficiencies. People with CVID have a weaker immune system than normal people. Although this disorder commonly affects adults, it can also occur in children. People with CVID are most susceptible to bacterial and viral infections. Common variable immunodeficiency can be either inherited or developed during a person’s lifetime.

What Is Common Variable Immunodeficiency (CVID)?

Common variable immunodeficiency is an immune deficiency disorder characterized by low antibody levels that fight infections in the body. Due to insufficient protective antibody levels, people with CVID are prone to recurrent infections. Infections of the sinuses, lungs, and ears are common in CVID. Recurrent infections of the lungs, like pneumonia, can often lead to chronic lung disease. People with CVID also have a high risk of developing autoimmune disorders, blood disorders, cancer, and digestive disorders.

What Are the Causes of Common Variable Immunodeficiency (CVID)?

In the majority of the cases, the cause of CVID is unknown. In about ten percent of the cases, genetic involvement has been identified. Researchers believe that CVID is caused due to the combined effect of both genetic and environmental factors. The causative environmental factors are unclear. But the genetic factors are believed to be a defect in the genes that are responsible for the development and functioning of the immune system cells called B cells. B cells are specific white blood cells that help the body fight against infections. When B cells mature, they make proteins called immunoglobulins (IgG) or antibodies. The defective genes cause the body to produce low levels of immunoglobulins. With low levels of IgG (Immunoglobulin G), it becomes hard for the body to fight against infections. Defects in at least 13 genes have been linked with CVID.

What Are the Symptoms of Common Variable Immunodeficiency (CVID)?

The symptoms of CVID can vary from person to person. The commonly seen signs and symptoms in people with CVID are as follows:

• Breathing difficulties.

• Ear infections.

• Sinusitis.

• Pneumonia.

• Bronchitis.

• Lymph node enlargement in the neck.

• Cough.

• Green or yellow sputum.

• Abdominal pain.

• Bloating.

• Nausea.

• Vomiting.

• Weight loss.

• Diarrhea.

• Painful inflammation of the joints like elbows, ankles, knees, and wrists.

• Hemolytic anemia.

How to Diagnose Common Variable Immunodeficiency (CVID)?

The ways to diagnose common variable immunodeficiency are as follows:

• The doctor takes a detailed family medical history of the persons who show unusual reactions to vaccines or have signs of an immune disorder. The doctor collects information about the infection history and digestive symptoms of the person.

• Both adults and children with a history of bacterial infections involving sinuses, bronchi, lungs, and ears should be suspected of CVID.

• Blood tests are done to evaluate the functioning of the immune system. The characteristic finding includes low serum immunoglobulin levels. IgG is low in most patients, whereas some patients have low IgM (Immunoglobulin M) and IgA (Immunoglobulin A).

• The doctor may give a vaccine for some other condition to check for the body’s response to immunization. This is done to determine the lack of functional antibodies. This is done by calculating the serum antibody levels against vaccine antigens like measles, tetanus, diphtheria, rubella, or mumps. CVID patients usually have very low antibody levels against these vaccines.

• In order to measure the antibody function, immunization is done using killed vaccines. Before starting the treatment, this test is usually done to decide whether immunoglobulin replacement therapy will benefit the patient.

What Are the Treatment Options for Common Variable Immunodeficiency (CVID)?

After diagnosing common variable immunodeficiency, the following treatment options are advised:

• Immunoglobulin Replacement Therapy (IRT):Patients should undergo immunoglobulin (IgG) replacement therapy to prevent infections. Before starting the therapy, the level of damage occurred to the lungs or other organs is assessed. This therapy should be carried out consistently throughout the life of the patient. This therapy replaces insufficient immunoglobulins with antibodies taken from the blood of healthy donors. The extracted immunoglobulin consists of IgG and all other important antibodies. This treatment is done either intravenously or through an injection below the skin.

• Medications:

  • Antibiotics are prescribed to treat the frequent infections caused by CVID.

  • Patients with chronic lung disease or chronic sinusitis often need long-term treatment with broad-spectrum antibiotics.

  • In some patients, antibiotics combined with immunoglobulin replacement therapy are advised as it shows effective results. Antibiotics combined with IRT can prevent the development of chronic lung disease.

  • Patients who have chronic infections like mycoplasma are given antibiotics specified for those organisms.

  • Cyclosporin A has shown effective results in people with CVID.

  • Patients with gastrointestinal infections like inflammatory bowel disease are treated with medications that are normally prescribed for non-immunodeficient patients. Patients who develop tumors or granulomas are also treated the same way as a normal immune person. However, patients with CVID would be less responsive to therapies compared to immune patients.

  • Corticosteroid therapy is advised for controlling autoimmune disease.

• Pulmonary Hygiene Regimen: Patients who develop bronchiectasis should undergo a pulmonary hygiene regimen daily. This involves chest physiotherapy and postural drainage to mobilize the secretions of both bronchi and the lungs. This would clear the airway secretions and make it easier for the patients to cough up. As patients with common variable immunodeficiency are prone to develop respiratory infections, they should undergo regular checkups, including lung function tests.

What Are the Complications of Common Variable Immunodeficiency (CVID)?

People with CVID are at high risk of developing certain complications. They are as follows:

• Bronchiectasis: It is the permanent damage that occurs to the lungs due to recurrent infections.

• Granulomas: A cluster of tissues seen as an area of inflammation in the lungs, skin, or other organs.

• Autoimmune Disorders: It is a condition in which the immune system mistakenly harms its own healthy cells or organs. People with CVID may develop autoimmune hemolytic anemia or immune thrombocytopenia.

• Cancers: People with CVID are at high risk of developing cancers of the gastrointestinal system, like stomach cancer, and of the lymphatic system, like lymphoma.

Conclusion:

As CVID is a condition with a genetic origin, it cannot be prevented. But with the right treatment, people with CVID can lead a normal life. When left untreated, CVID can lead to serious complications like lung damage or cancer. Hence it is important to consult a doctor if a person develops repeated or frequent infections or other CVID symptoms.