Immunosuppression involves an act that reduces the activation or
efficacyof the immune system. Some portions of the immune system itself have immuno-suppressive effects on other parts of the immune system, and immunosuppression may occur as an adverse reaction to treatment of other conditions. Deliberately induced immunosuppression is generally done to prevent the body from rejecting an organ transplant, treating graft-versus-host diseaseafter a bone marrow transplant, or for the treatment of auto-immune diseases such as rheumatoid arthritisor Crohn's disease. This is typically done using drugs, but may involve surgery (splenectomy), plasmapharesis, or radiation.
A person who is undergoing immunosuppression, or whose immune system is weak for other reasons (for example,
chemotherapyand HIVpatients) is said to be "immunocompromised". When an organ is transplanted, the immune system of the recipient will most likely recognize it as foreign tissue and attack it. The destruction of the organ will, if untreated, end in the death of the recipient.
In the past,
radiation therapywas used to decrease the strength of the immune system, but now immunosuppressant drugs are used to inhibit the reaction of the immune system. The downside is that with such a deactivated immune system, the body is very vulnerable to opportunistic infections, even those usually considered harmless. Also, prolonged use of immunosuppressants increases the risk of cancer. Cortisonewas the first immunosuppressant identified, but its wide range of side effects limited its use. The more specific azathioprinewas identified in 1959, but it was the discovery of cyclosporine in 1970 that allowed for significant expansion of kidney transplantationto less well-matched donor-recipient pairs as well as broad application of liver transplantation, lung transplantation, pancreas transplantation, and heart transplantation.
Joseph Murrayof Harvard Medical Schooland chief plastic surgeon at Children's Hospital Bostonfrom 1972-1985 was awarded the Nobel Prize in Physiology or Medicinein 1990 for his work on immunosuppression. Dr. Murray and his team are credited with first successful human kidney transplant at Peter Bent Brigham Hospital, Boston on 23 December 1954.
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