Immunoglobulin deficiency syndromes
Immunoglobulin deficiency syndromes are a group of immunodeficiency disordersin which the patient has reduced number of or lack of antibodies.
Immunoglobulins (Ig) are antibodies. There are five major classes of antibodies: IgG, IgM, IgA, IgD, and IgE.
- IgG is the most abundant of the classes of immunoglobulins. It is the antibody for viruses, bacteria, and antitoxins. It is found in most tissues and plasma.
- IgM is the first antibody present in an immune response.
- IgA is an early antibody for bacteria and viruses. It is found in saliva, tears, and all other mucous secretions.
- IgD's activity is unknown.
- IgE is present in the respiratory secretions. It is an antibody for parasitic diseases, hay fever, and allergic asthma.
All antibodies are made by B-cells. Any disease that harms the development orfunction of these cells will cause a decrease in the amount of antibodies produced. Since antibodies are essential in fighting infectious diseases, people with immunoglobulin deficiency syndromes become ill more often. However, the cellular immune system is still functional, so these patients are more prone to infection caused by organisms usually controlled by antibodies.
There are two types of immunodeficiency diseases: primary and secondary. Secondary disorders occur in normally healthy bodies that are suffering from an underlying disease. Once the disease is treated, the immunodeficiency is reversed. Immunoglobulin deficiency syndromes are primary immunodeficiency diseases, occurring because of defective B lymphocytes or antibodies. They account for 50% of all primary immunodeficiencies, and they are, therefore, the most prevalent type of immunodeficiency disorders.
Immunoglobulin deficiencies are the result of congenital defects affecting the development and function of B lymphocytes (B-cells). There are two main points in the development of B-cells when defects can occur. First, B-cells canfail to develop into antibody-producing cells. Second, B-cells can fail to make a particular type of antibody or fail to switch classes during maturation.Initially, when B-cells start making antibodies for the first time, they make IgM. As they mature and develop memory, they switch to one of the other four classes of antibodies. Failures in switching or failure to make a subclassof antibody leads to immunoglobulin deficiency diseases.
Symptoms are persistent and frequent infections, diarrhea, failureto thrive, and malabsorption (of nutrients).
An immunodeficiency disease is suspected when children become ill frequently,especially from the same organisms. Laboratory tests are performed to verifythe diagnosis. Antibodies can be found in the blood. Depending on the type of immunoglobulin deficiency the laboratory tests will show a decrease or absence of antibodies or specific antibody subclasses.
Immunodeficiency diseases can not be cured. Patients are treated with antibiotics and immune serum. Immune serum is a source of antibodies. Antibiotics are useful for fighting bacteria infections. There are some drugs that are effective against fungi, but very few drugs that are effective against viral diseases.
Bone marrow transplantation can, in most cases, completely correct the immunodefiency.
Patients with immunoglobulin defiency syndromes must practice impeccable health maintenance and care, paying particular attention to optimal dental care,in order to stay in good health.