Types of PI
Primary immunodeficiency (PI) diseases are characterized in many different ways, including:
- Low antibody levels
- Defects in antibodies
- Defects in the cells and proteins of the immune system (for example, T cells, B cells, neutrophils, or the complement system)
These defects make people susceptible to recurrent infections, and other complications that may require different therapies. The most common primary immunodeficiency types result in an inability to make a very important type of protein called antibodies or immunoglobulins, which help the body fight off infections from bacteria or viruses. In addition to increased susceptibility to infection, people with PI may also have autoimmune diseases in which the immune system attacks their own cells or tissues.