Immunodeficiency disorders interfere with the functioning of the immune system. As a result, the body is less able to fight off attacks, such as those from bacteria, viruses, and fungi.
A person with this type of disorder is more likely to experience frequent infections affecting the gastrointestinal tract, sinuses, ears, and lungs, as well as other more serious and potentially life-threatening illnesses.
There is significant variation among immunodeficiency disorders. Primary immunodeficiency disorders are genetic and passed through generations. Researchers have identified more than 300 of these genetic disorders.
The immune system fights infection in two ways: T cells work to destroy the infectious agent directly, while B cells produce antibodies to eradicate it.
Each method involves a variety of cells that are all made in a person's bone marrow. B cells mature in the marrow, and T cells mature in the thymus, a gland that sits behind the breast bone.
Mature cells then move to the spleen and lymph nodes, where they wait for the signal to fight infection.
These cells also move to locations where they can detect and fight infectious agents as they enter the body. These areas include the:
Other areas have special tissue that contains these cells, including the:
- Peyer's patches, which are parts of the small intestine
All immunodeficiency disorders result from a problem with one or more components of the immune system.
Although scientists once considered these disorders to be rather rare, better diagnostic tools and understanding suggest that they may be more widespread. The Immune Deficiency Foundation report that as many as 1 in every 1,200–2,000 people could have a primary immunodeficiency disorder.
Common variable immune deficiency is the immunodeficiency disorder that occurs most frequently, and roughly 1 in every 25,000 people have it.
The two main types of immunodeficiency disorder are: primary and secondary.
Within these categories there are distinctions. Among primary immunodeficiency disorders, there are:
- antibody deficiencies, involving low levels of a single type of antibody
- combined immunodeficiencies, involving low levels of more than one type of antibody
- combined immunodeficiencies with syndromes, such as eczema
- severe combined immunodeficiencies, involving both innate and adaptive immunity malfunction
- phagocytic defects, affecting the ability of certain white blood cells to ingest and destroy an infective agent
- complement deficiencies, involving low levels of proteins in the complement system, which plays an important role in fighting infections
- cellular immune deficiency or innate immunity disorders, which hinder a person's ability to directly fight infections without antibodies
- immune dysregulation, a term for genetic disorders that affect the entire immune system, causing multiple systems to malfunction
Secondary immunodeficiency disorders have similar core symptoms to primary disorders. The ways that these conditions progress depends on the circumstances that led to their development.
For example, a person who has immunodeficiency because they were receiving chemotherapy will have different symptoms and require different treatment from a person with an immunodeficiency that results from HIV.
Primary immunodeficiency disorders have direct links to genetics, so one of the most significant risk factors is having a family member with this type of condition.
The Immune Deficiency Foundation report that diagnosing an immunodeficiency disease typically takes 9–15 years.
The lag between initial symptoms and effective treatment leads to permanent damage in 37 percent of people with this type of condition.
More rapid diagnosis and treatment could reduce this figure, so experts urge individuals with frequent, serious, long-lasting, or unusual infections to speak to a doctor.
Because secondary immunodeficiency disorders have a wide range of causes, they also have a broad range of risk factors, including:
- IV drug use
- unsafe sexual practices
- limited access to nutrition
- poor overall physical condition
- the number of medications used
Age is also a risk factor, with premature infants and older adults more likely to have secondary immune deficiencies.
It is important to note that immunodeficiency disorders can also be risk factors for other health issues. A person with this type of disorder may be more likely to develop an autoimmune disease or certain cancers, for example.
Because there is such variety among immunodeficiency disorders, their symptoms can also vary significantly.
However, the most basic symptom of a primary or secondary immunodeficiency disorder is a tendency to get recurrent infections that are serious, difficult to treat, and do not go away as expected.
Below are other general issues that can indicate an immunodeficiency disorder:
- weight loss
- slow growth, in children
- swollen glands
- a low platelet count
- swollen joints
- frequent abscesses
- skin rashes
- food allergies
- gum problems
The symptoms of an immunodeficiency disorder have direct links to the affected parts of the immune system.
For example, when this type of disorder affects the B cells, which make antibodies, recurring bacterial infections can be a common problem. But when the disorder impairs parts of the immune system involving both the B and T cells, a wide variety of organisms, including fungi, bacteria, and viruses, can easily cause infection.
Specific immunodeficiency disorders have certain associations. For example:
- Antibody deficiencies have links to frequent infections, particularly from bacteria.
- Phagocytic defects can lead to slow wound healing and clusters of immune cells called granulomas.
- Some forms of complement deficiencies can result in liver infections, while individuals with other forms may be prone to autoimmune diseases.
- Immune dysregulation may increase the risk of developing an autoimmune disease.
Primary immunodeficiency disorders result from genetic mutations.
In some cases, scientists have not been able to identify the pathway that these mutations follow. This is true for common variable immune deficiency, as an example.
Secondary immunodeficiency disorders develop in response to experiences, such as infections or treatments.
Some of the causes include:
- infections, such as with HIV, the Epstein-Barr virus, or the cytomegalovirus
- surgery, involving the removal of the spleen, stem cell transplants, or anesthesia, for example
- poor nutrition, possibly due to deficiencies in zinc or other vitamins or minerals
- severe burns
- treatment with immunosuppressant drugs
- antiepileptic medications
For people with primary immunodeficiency disorders, preventing infection is very important, as they have a higher overall risk. Experts urge these individuals to:
- Be vigilant about hygiene in all respects, especially hand-washing.
- Adopt a healthful lifestyle, involving a nutritious diet, adequate exercise, and plenty of rest.
- Limit contact with people who are sick.
- Take advantage of vaccines and immunizations when appropriate.
- See healthcare providers for regular checkups and evaluations.
- Safeguard mental and spiritual health.
Physicians use medications to treat the infections that result from reduced immune system function and to address the underlying disorder.
People with low T cell counts, for example, frequently receive treatment for opportunistic infections before they even get them, while people with low levels of the immunoglobulin G antibody may receive monthly shots to maintain their levels.
It is possible to prevent some secondary immunodeficiency disorders. For example, a person can try to avoid contracting HIV by using a condom and not sharing needles.
In other situations, such as when receiving chemotherapy, taking steps to avoid an immunodeficiency disorder could pose a greater threat to the person's overall health.
Bone marrow transplants can improve immune system function in people with some primary immunodeficiency disorders that are severe and affecting the overall quality of life. Researchers are also exploring the potential of gene therapy.