Non-infectious complications of PIDs


The human immune system has many overlapping layers of defences. These include a diverse collection of cells, proteins, tissues and organs. Normally these all interact in a complex and intricately balanced way to maintain health and fight off infection. However, the genetic abnormalities that cause primary immune deficiency disorders (PIDs) can, in certain circumstances, upset this delicate balance. When this happens, parts of the immune system can become overactive, poorly regulated or directed, which can lead to development of complications (see below) such as inflammation, allergy, autoimmune disease or, rarely, cancer.

So, having a PID does not just cause an increased risk of infections; it can result in other health problems. These include where a person’s immune system:

  • Starts attacking the body’s own cells and tissues. Disorders where this happens are known as autoimmune diseases. One example of this is the abnormal production by the body of antibodies that can attack and kill red blood cells. This would cause a person to have anaemia.
  • Reacts to normally harmless substances that surround us every day. These are called allergies but can also be referred to as hypersensitivities. A common allergy that many people have heard of is an allergy to pollen. This causes hay fever.
  • Produces unusual forms of inflammation by forming organised clumps or nodules of immune cells in tissues or organs of the body. This is known as granulomatous disease. The nodules may cause discomfort and pain, and/or interfere with the working of the body’s organs and tissues.
  • Is poorly regulated or directed and does not deal effectively with specific kinds of triggers which can, in some circumstances, lead to development of a range of cancers.

In summary, disease and tissue damage in PIDs can happen as a result of infections, an unbalanced immune system or a combination of both. The sections below take you through these different complications of PIDs and how they are diagnosed and treated.

This page was reviewed by the Medical Advisory Panel, April 2018.