Immunodeficiency disorders interfere with the healthy function of the immune system. As a result, the body is less able to fight off attacks by bacteria, viruses, or fungi.
Immunodeficiency disorders can cause frequent infections in the gastrointestinal tract, sinuses, ears, or lungs. They can also lead to more serious and potentially life threatening conditions.
There are many immunodeficiency disorders, and they affect the body in different ways. Primary immunodeficiency disorders are genetic. This means that they can pass from parents to children through generations. Researchers have identified more than 400 of these genetic disorders.
People can also get secondary immunodeficiency disorders due to an illness, an infection, or malnutrition. Certain treatments — such as chemotherapy, immune modulator therapy, or surgery — can also be a cause.
This article discusses the causes, risk factors, examples, and symptoms of different types of immunodeficiency disorders.
The immune system helps people fight pathogens that invade their bodies. Two parts make up the immune system: innate and adaptive immunities.
Innate immunity is the first line of defense against infections that can enter the body through the skin and mucous membranes. These barrier tissues and their immune cells stop infections from spreading deeper into the body.
The cells of the innate immune system also activate a more specific and long lived immune response called adaptive immunity. Certain types of white blood cells encompass, ingest, and kill bacteria or viruses as part of the first line of defense.
Adaptive immunity consists of T cells that can attack the infectious agent directly or provide help to B cells that produce pathogen antibodies to help eradicate the cause of an infection.
The bone marrow makes the cells necessary for the immune system to do its job. B cells mature in the marrow, and T cells mature in the thymus, which is 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 can move to and stay in locations to better detect and fight infectious agents entering the body. These areas include the:
eyes
nose
mouth
intestines
Other areas have special tissue that contains these cells, including the:
The complement system is also a major part of the immune system. It can activate more than 30 different kinds of special proteins. When these proteins encounter a pathogen, they can help immune cells launch a response.
People who have an immunodeficiency disorder have a problem with one or more of the components of their immune system.
Scientists once considered these disorders to be rare. However, better diagnostic tools and understanding show that they may be more widespread. In fact, as many as 1 in every 1,200–2,000 people could have a primary immunodeficiency disorder.
The immunodeficiency disorder that occurs most frequently is common variable immune deficiency. About 1 in every 25,000 people have it.
The two main types of immunodeficiency disorders are primary and secondary. Within these categories, there are distinctions.
Among primary immunodeficiency disorders, there are:
antibody deficiencies that create low levels of a single type of antibody class
combined immunodeficiencies that create low levels of more than one antibody class
combined immunodeficiencies with conditions such as eczema
severe combined immunodeficiencies that involve both innate and adaptive immune system malfunctions
phagocytic defects that prevent white blood cells from ingesting and destroying a pathogen
complement deficiencies that involve low levels of proteins in the complement system
cellular immune deficiency or innate immunity disorders that prevent people from fighting infections without antibodies
an immune dysregulation that causes several immune systems to malfunction
Secondary immunodeficiency disorders have similar core symptoms to primary disorders. How these conditions progress depends on the circumstances that led to their development.
For example, one person may have an immunodeficiency that resulted from chemotherapy. Another person may have an immunodeficiency that resulted from HIV. These people may have different symptoms and require different treatment.
Diagnosing an immunodeficiency disorder has typically taken 9–15 years. The delay between initial symptom onset and receiving effective treatment leads to permanent damage in 37% of affected people.
However, more rapid diagnosis and treatment can reduce this figure. Experts urge individuals with frequent, serious, long lasting, or unusual infections to speak with a doctor. It is also important to find out if any relatives have had problems with infections and share this information with the doctor.
Primary immunodeficiency disorders result from genetic mutations. Scientists have not identified all the genetic pathways that these mutations follow. This is true for common variable immune deficiency, for example.
Secondary immunodeficiency disorders develop in response to environmental factors. They have a wide range of causes and a broad range of risk factors, including:
Immunodeficiency disorders can also be risk factors for other health issues. A person with an immunodeficiency disorder may be more likely to develop autoimmune conditions or certain cancers, for example.
The variations in immunodeficiency disorders mean that the symptoms can vary significantly. The most basic symptom is a tendency for recurring infections. These infections may be serious, be difficult to treat, and last longer than expected.
Below are some other general issues that can indicate an immunodeficiency disorder:
The symptoms of an immunodeficiency disorder have direct links to the affected part of the immune system. When the disorder affects the B cells, for example, a person may get recurring bacterial infections. On the other hand, when the disorder affects both the B and T cells, a person may get infections from fungi, bacteria, or viruses.
Specific immunodeficiency disorders have certain associations. For example:
Antibody deficiencies have links to frequent infections 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. Individuals with other forms may be prone to autoimmune conditions.
Immune dysregulation may increase the risk of developing an autoimmune condition or cancer.
People with primary immunodeficiency disorders need to be extra careful to avoid getting an infection. Experts urge these individuals to:
Be vigilant about hygiene in all respects, especially hand-washing.
Follow a healthy lifestyle consisting of a balanced diet, regular exercise, and plenty of rest.
Limit contact with people who are sick.
Take advantage of vaccines and immunizations when appropriate.
Contact a doctor for regular checkups and evaluations.
Safeguard one’s mental health.
Doctors can use medications to treat infections that result from reduced immune system function. People with low T cell counts, for example, can frequently receive treatment before they even get an infection. On the other hand, people with low levels of the immunoglobulin G antibody may receive monthly shots to maintain their levels.
In the case of chemotherapy treatment for cancer, a person may not be able to avoid the immunodeficiency that results. In this situation, there are treatment options for low white blood cells, for example.
Bone marrow transplants can improve immune system function in people with some primary immunodeficiency disorders, but potential complications are significant. Researchers are now exploring gene therapy for several of these disorders.
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