The majority of patients with primary immunodeficiency have a defect in their ability to make sufficient quantities of specific antibodies. This lack of specific antibodies is due to the lack of B lymphocytes, defects in B-lymphocyte function, or inability of B lymphocytes to interact with T lymphocytes. Patients born with only antibody deficiency usually appear normal at birth due to maternal antibodies that crossed the placenta. They usually start developing more infections at around six months of age when maternal antibodies have been depleted, and they cannot make their own antibodies. Treatment may include prophylactic antibodies until diagnosis is confirmed or infusion of immunoglobulin, either by intravenous route or subcutaneously. When patients have antibody deficiency plus defects in T lymphocytes, the disease is usually more severe and will be further discussed in other articles.

Key Concepts:

• The most severe form of antibody deficiency, Bruton's, requires regular infusions of IVIG starting in infancy.
  
• Common variable immunodeficiency (CVID) is often associated with autoimmune disease as well as malignancies.
  
• Less severe forms of B-cell deficiency may be managed with prophylactic antibiotics.
  
• Severe combined immunodeficiency (SCID) requires stem cell transplantation for treatment.
  
• Early diagnosis is essential in preventing long-term disability or early death