Primary Immune System Deficiency Program (Primary Immunodeficiency)

In many of the cases that we treat at the Primary Immune Deficiency Program of The Mount Sinai Hospital, a child or adult who experiences “too many infections” over a short period may be diagnosed with an immune system deficiency. In some cases, the cause is a genetic defect that has been present from birth.

Typically, patients with primary immunodeficiency disorder experience numerous respiratory or systemic infections that a healthy immune system would fight before symptoms develop. In other patients – adults as well as children and infants – weight loss, chronic gastrointestinal infections, and autoimmune disease such as immune thrombocytopenia, hemolytic anemia, vitiligo, or pernicious anemia may signal a disorder of the immune system.

Many people believe that primary immunodeficiency disorder is typically diagnosed only in infants and young children. That’s not accurate. In our experience, we have found that adult patients who may not look ill may have a significant immune system defect that can and should be treated.


The Human Immune System

To understand primary immunodeficiency disorders, it may help to understand how a healthy immune system works. The body is organized by cell units or divisions into an automatically balanced system that keeps us healthy. This system is made up of specialized cells that routinely regulate everyday functions such as body temperature, blood volume, and the ability to fight disease. Any challenge to this delicate balance is usually met by resistance from the system or systems under attack.

In a healthy human being, the body has an inborn defense system against disease called natural immunity. From birth, individual cell groups are poised to fight invaders such as bacteria entering the body. These “immune cells” are known as lymphocytes, or white blood cells (WBCs). Among these WBCs are even more specialized cell groups. Each has its own genetically programmed function, much like the rank of soldiers in an army.

When disease-causing bacteria enter the bloodstream from a cut, for example, these invaders are identified as the enemy and the immune system “army” is put on alert. Immediately, pathogen-destroying foot soldiers called macrophages speed up bloodstream activity to root out these disease carriers. This immediate response to invasion in the form of antibody production is known as the primary immune response.

In those with primary immune disorders, however, this natural defense system breaks down. That’s why many people with primary immune system disorders experience frequent infections.