Immunoglobulin G Deficiency

November 12, 2012

Immunoglobulin G Deficiency

Immunoglobulin G is the most abundant class of antibody in the body and is found in plasma as well as in external secretions. It reacts with antigens on the surface of pathogens such as bacteria and neutralizes them.

Overview

Immunoglobulin G plays an important role in your immune system’s defense against bacteria, viruses and fungi. It protects the tissues in the body by neutralizing bacterial toxins and enhancing phagocytosis of the pathogens. IgG is further divided into four subclasses: IgG1, IgG2, IgG3 and IgG4. The deficiency of IgG can be divided into two categories as well. Selective immunoglobulin G deficiency is characterized by low levels of IgG with normal levels of other immunoglobulin classes. The second category involves deficiency of all the immunoglobulin classes.

Adults and children over the age of 2 years may suffer from IgG deficiency with a prevalence rate of 1 case per 10,000 persons. Most experts believe that mutations to the genes responsible for the production of the antibody cause IgG deficiency. Smoking and aging may increase the risk of this condition. The disease can also occur if the body mistakenly produces antibodies to destroy its own IgG.

Symptoms

Recurrent infections of the same organ or with the same pathogen often indicate immunoglobulin G deficiency. Most individuals with IgG deficiency have a family history of such conditions. Patients are prone to dental or oral diseases as well as respiratory tract infections. They often experience low-grade fever, middle ear infections, headache and cough. IgG2 deficiency increases your risk of Hemophilus influenzae type b and Streptococcus pneumoniae infections. IgG3 deficiency, on the other hand, is associated with infections caused by pathogens such as Moraxella catarrhalis. IgG4 deficiency occurs in 10 to14 percent of the general population. However, the clinical significance of this deficiency is unknown, although some cases of recurrent respiratory tract infections have been reported.

Diagnosis

If you suffer from recurrent infections, your doctor may order lab tests to detect the immunoglobulin G levels in your blood. Most laboratories will draw a blood sample from your arm and perform an enzyme-linked immunosorbent essay, or ELISA, to detect the antibodies. The tetanus/diphtheria antibodies are evaluated to determine the IgG1 levels while meningococcal or pneumococcal antigen levels are used to identify IgG2 and IgG3 levels. Your body may, however, have optimum total IgG and IgG subclass levels and still fail to produce the antibody against a specific pathogen. Pulmonary function tests and bacterial cultures may also be useful in case of respiratory tract infections.

Treatment

The first step in the management of immunoglobulin G deficiency is to treat the infection with antibiotics. Intravenous immunoglobulin G replacement therapy may help elevate IgG levels. The replacement therapy may, however, lead to side effects such as headache, fever, chills and mild nausea. Vaccination against the specific bacteria may also help your immune system to generate the required antibodies. Severe cases may require endoscopic surgery to remove the infections.

Most patients can expect relief from infections after the treatment. Regular monitoring may be required for a short period to see the impact of the replacement therapy.

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