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Immunosuppression is a reduction of the activation or
efficacy Efficacy is the ability to perform a task to a satisfactory or expected degree. The word comes from the same roots as ''effectiveness'', and it has often been used synonymously, although in pharmacology a distinction is now often made between ...
of the
immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinte ...
. Some portions of the immune system itself have immunosuppressive effects on other parts of the immune system, and immunosuppression may occur as an adverse reaction to treatment of other conditions. In general, deliberately induced immunosuppression is performed to prevent the body from rejecting an
organ transplant Organ transplantation is a medical procedure in which an organ is removed from one body and placed in the body of a recipient, to replace a damaged or missing organ. The donor and recipient may be at the same location, or organs may be transpor ...
. Additionally, it is used for treating
graft-versus-host disease Graft-versus-host disease (GvHD) is a syndrome, characterized by inflammation in different organs. GvHD is commonly associated with bone marrow transplants and stem cell transplants. White blood cells of the donor's immune system which remain ...
after a
bone marrow transplant Hematopoietic stem-cell transplantation (HSCT) is the transplantation of multipotent hematopoietic stem cells, usually derived from bone marrow, peripheral blood, or umbilical cord blood in order to replicate inside of a patient and to produce ...
, or for the treatment of auto-immune diseases such as
systemic lupus erythematosus Lupus, technically known as systemic lupus erythematosus (SLE), is an autoimmune disease in which the body's immune system mistakenly attacks healthy tissue in many parts of the body. Symptoms vary among people and may be mild to severe. Commo ...
,
rheumatoid arthritis Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and hands are inv ...
, Sjögren's syndrome, or
Crohn's disease Crohn's disease is a type of inflammatory bowel disease (IBD) that may affect any segment of the gastrointestinal tract. Symptoms often include abdominal pain, diarrhea (which may be bloody if inflammation is severe), fever, abdominal distensi ...
. This is typically done using medications, but may involve surgery ( splenectomy), plasmapheresis, or radiation. A person who is undergoing immunosuppression, or whose immune system is weak for some other reasons (such as
chemotherapy Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs (chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemother ...
or HIV), is said to be '' immunocompromised''.


Deliberately induced

Administration of immunosuppressive medications or immunosuppressants is the main method for deliberately inducing immunosuppression; in optimal circumstances, immunosuppressive drugs primarily target hyperactive components of the immune system. People in remission from cancer who require immunosuppression are not more likely to experience a recurrence. Throughout its history,
radiation therapy Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Rad ...
has been used to decrease the strength of the immune system. Dr. Joseph Murray of Brigham and Women's Hospital was given the
Nobel Prize in Physiology or Medicine The Nobel Prize in Physiology or Medicine is awarded yearly by the Nobel Assembly at the Karolinska Institute for outstanding discoveries in physiology or medicine. The Nobel Prize is not a single prize, but five separate prizes that, accordi ...
in 1990 for work on immunosuppression. Immunosuppressive drugs have the potential to cause
immunodeficiency Immunodeficiency, also known as immunocompromisation, is a state in which the immune system's ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that a ...
, which can increase susceptibility to
opportunistic infection An opportunistic infection is an infection caused by pathogens (bacteria, fungi, parasites or viruses) that take advantage of an opportunity not normally available. These opportunities can stem from a variety of sources, such as a weakened immun ...
and decrease
cancer immunosurveillance Cancer immunology is an interdisciplinary branch of biology that is concerned with understanding the role of the immune system in the progression and development of cancer; the most well known application is cancer immunotherapy, which utilise ...
. Immunosuppressants may be prescribed when a normal immune response is undesirable, such as in
autoimmune diseases An autoimmune disease is a condition arising from an abnormal immune response to a functioning body part. At least 80 types of autoimmune diseases have been identified, with some evidence suggesting that there may be more than 100 types. Nearly a ...
. Steroids were the first class of immunosuppressant drugs identified, though side-effects of early compounds limited their use. The more specific azathioprine was identified in 1960, but it was the discovery of ciclosporin in 1980 (together with azathioprine) that allowed significant expansion of transplantation to less well-matched donor-recipient pairs as well as broad application to
lung transplantation Lung transplantation, or pulmonary transplantation, is a surgical procedure in which one or both lungs are replaced by lungs from a donor. Donor lungs can be retrieved from a living or deceased donor. A living donor can only donate one lung lobe. ...
, pancreas transplantation, and heart transplantation. After an
organ transplantation Organ transplantation is a medical procedure in which an organ is removed from one body and placed in the body of a recipient, to replace a damaged or missing organ. The donor and recipient may be at the same location, or organs may be transpor ...
, the body will nearly always reject the new organ(s) due to differences in
human leukocyte antigen The human leukocyte antigen (HLA) system or complex is a complex of genes on chromosome 6 in humans which encode cell-surface proteins responsible for the regulation of the immune system. The HLA system is also known as the human version of th ...
between the donor and recipient. As a result, the immune system detects the new tissue as "foreign", and attempts to remove it by attacking it with
white blood cells White blood cells, also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from mult ...
, resulting in the death of the donated tissue. Immunosuppressants are administered in order to help prevent rejection; however, the body becomes more vulnerable to infections and malignancy during the course of such treatment.


Non-deliberate immunosuppression

Non-deliberate immunosuppression can occur in, for example, ataxia–telangiectasia, complement deficiencies, many types of
cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
, and certain chronic infections such as human immunodeficiency virus (HIV). The unwanted effect in non-deliberate immunosuppression is
immunodeficiency Immunodeficiency, also known as immunocompromisation, is a state in which the immune system's ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that a ...
that results in increased susceptibility to
pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a g ...
s, such as bacteria and viruses. Immunodeficiency is also a potential adverse effect of many
immunosuppressant drug Immunosuppressive drugs, also known as immunosuppressive agents, immunosuppressants and antirejection medications, are drugs that inhibit or prevent activity of the immune system. Classification Immunosuppressive drugs can be classified into ...
s, in this sense, the scope of the term ''immunosuppression'' in general includes both beneficial and potential adverse effects of decreasing the function of the immune system.
B cell B cells, also known as B lymphocytes, are a type of white blood cell of the lymphocyte subtype. They function in the humoral immunity component of the adaptive immune system. B cells produce antibody molecules which may be either secreted o ...
deficiency and
T cell A T cell is a type of lymphocyte. T cells are one of the important white blood cells of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell r ...
deficiency are immune impairment that individuals are born with or are acquired, which in turn can lead to immunodeficiency problems. Nezelof syndrome is an example of an immunodeficiency of T-cells.


See also


References


Further reading

* Retrieved 6 May 2017. *


External links


PubMed
{{Medicine, state=collapsed Immune system Immunology Medical treatments it:Immunodepressione