Selective Antibody Deficiency (SAD)
Selective antibody deficiency (SAD) is an immune deficiency disorder and is characterized by an inadequate response to certain types of antigens (foreign substances in the body) but not to others, even though people have normal or near normal levels of antibodies (immunoglobulins). In SAD, the body is unable to produce specific antibodies, resulting in susceptibility to certain kinds of infections, but not others.
Symptoms of SAD
Patients with selective antibody deficiency (SAD) may have symptoms which include recurrent ear infections, sinusitis, bronchitis and pneumonia. Infections in SAD patients are not as severe as in patients who have other types of immune deficiencies such as agammaglobulinemia or Common Variable Immune Deficiency.
An evaluation typically includes measurement of total immunoglobulin type G (IgG), IgG subclasses and antibody titers to specific bacteria such as tetanus, diphtheria, and/or Streptococcus pneumoniae. When the total IgG or subclasses are low, a more profound immunodeficiency is usually present.
Patients with selective antibody deficiency (SAD) who frequently suffer recurrent or chronic infections of the ears, sinuses, bronchi and lungs require antibiotics. Immune globulin replacement therapy is needed for patients who fail to make antibodies against proteins or polysaccharide antigens. Immune globulin is extracted from a large pool of human plasma and contains all the important antibodies present in the normal population. Immune globulin therapy can be administered into the blood stream intravenously (IVIG) or under the skin subcutaneously (SCIG).
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