Immunosuppression
Immunosuppression refers to a state where the immune system's activity is diminished, impairing its ability to combat infections and other threats. This condition can arise naturally due to medical issues or can be intentionally induced through treatments for conditions like autoimmune diseases, organ transplants, or cancers. In clinical contexts, immunosuppression may be necessary to prevent the body from rejecting transplanted tissues or to manage an overactive immune response. While the use of immunosuppressant drugs, such as corticosteroids and other targeted therapies, can provide therapeutic benefits, it also increases vulnerability to infections, known as opportunistic infections, due to a weakened immune defense.
The immune system comprises various components—including lymph nodes, bone marrow, and white blood cells—that work together to identify and eliminate foreign invaders like bacteria and viruses. Immunosuppression can be temporary or chronic, with causes ranging from medical interventions to inherited disorders. Testing is essential to diagnose immunosuppression, guiding medical professionals in determining the underlying issues and appropriate treatments. Understanding immunosuppression is crucial for managing health, particularly for individuals at increased risk of infections or those undergoing specific therapies.
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Immunosuppression
Immunosuppression is a term used to describe an immune system that has reduced activity and is impaired or not able to carry out its usual tasks, such as fighting off infections. In a clinical setting, the term is often used when discussing adverse reactions to a medical condition or the treatments involved. Sometimes, immunosuppression is intentionally induced to ensure that the body does not react badly to a treatment or procedure. Immunosuppressant drugs are used to treat some auto-immune diseases in which the body’s immune system is hyperactive. Individuals who are undergoing immunosuppression treatment or whose immune system has reduced function for other reasons are referred to as immunocompromised. The term immunosuppression has both positive and negative connotations as decreasing the activity of the immune system can be beneficial or harmful depending on the circumstances.
Background
The immune system is a collection of bodily structures and processes that protect the body from illnesses and diseases. A well-functioning immune system is able to identify and attack dangerous foreign invaders called antigens. Antigens can be toxins, bacteria, viruses, cancer cells, foreign blood or tissues, and parasites. The immune system distinguishes these invaders from the body’s healthy cells and tissues, knowing to fight off the dangerous substances while protecting the body’s interiors. When the immune system detects antigens, it releases antibodies, which are substances that destroy the harmful antigens. People are born with an innate immune system consisting of components such as the skin, mucus, and cough reflexes. It also involves the presence of certain innate substances in the body that keep the body healthy. People develop an adaptive immune system as they grow older and their body learns to fight off outside threats.
The major components of the immune system include the lymph nodes, bone marrow, the spleen, white blood cells called lymphocytes and leukocytes, and the thymus. These structures are all part of the lymphatic system. The lymph nodes produce and store infection and disease-fighting cells. They also contain a fluid called lymph that carries these cells to other parts of the body. Sometimes the lymph nodes swell and become sore when an infection is present. The spleen is also a cell-holding structure and helps the body get rid of old or damaged blood cells. The bone marrow produces white blood cells that help immunity. Lymphocytes create antibodies that attack infectious agents. Certain lymphocytes mature within the thymus, which helps release white blood cells when needed. Leukocytes perform a similar function as lymphocytes and are considered an important element of the innate immune system.
Immune diseases range in severity. Some conditions involve an immune deficiency while others involve an overactive immune system. Mild immune diseases include common conditions such as allergies, asthma, and eczema. More severe immune diseases include autoimmune diseases such as lupus or rheumatoid arthritis. Autoimmune diseases are caused by an overactive immune system, which sees the immune system attacking normal, healthy tissue as if it is a dangerous invader. Some immune system disorders can lead to inflammatory diseases and cancer. Immune deficiency conditions such as AIDS or severe combined immunodeficiency (SCID) involve an underperformance of the immune system, which makes people especially susceptible to foreign invaders. Some immune deficiency conditions are the result of deliberate immunosuppression, which is necessary when the immune system becomes overactive. In those patients with inherited immunosuppressive conditions, antibody replacement therapy is sometimes necessary to ensure that the immune system continues to function properly.
Overview
Intentional immunosuppression is most often implemented following an organ or a bone marrow transplant. Immunosuppression is performed to keep an organ or a bone marrow recipient’s body from rejecting the new tissue, which it considers a foreign substance. Immunosuppression is also deliberately induced in individuals with autoimmune diseases such as lupus or Crohn’s disease. Immunosuppression can be intentionally induced via immunosuppressant drugs or through certain procedures such as radiation therapy or surgery.
Immunosuppressant drugs are designed to target the hyperactive aspect of the immune system. Immunosuppressant drugs can lead to immunodeficiency in patients, making them more susceptible to opportunistic infections. It also has the potential to reduce the body’s immune surveillance abilities that help identify toxins such as cancer cells. The most common type of immunosuppressant drug is corticosteroids, which suppress the immune system and the inflammation it causes in the body. Other immunosuppressant drugs include Janus kinase inhibitors, calcineurin inhibitors, mTOR inhibitors, IMDH inhibitors, biologics, and monoclonal antibodies.
Immunosuppression can also be non-deliberate and occur in the body as a result of medical conditions such as chronic infections, neurodegenerative diseases, or cancer. Diseases such as human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS) cause immunosuppression in patients that increases their chances of contracting microbial infections. These patients often die of so-called opportunistic infections, which are infections that are able to develop more efficiently inside the body because of the failed immune response. Immunosuppression can also be congenital in instances where a person is born with a deficiency of certain types of white blood cells, leading to immunodeficiency disorders. Inherited immunosuppression is determined through blood tests that check white blood cell counts and levels of immunoglobulins, or proteins involved in fighting infections. Other tests can also assess a person’s cellular and humoral immunity (antibody production). Testing helps medical professionals diagnose the primary location of immune system malfunction and determine a course of action.
Bibliography
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