Immunosupresiva

Further information: Immunosuppressive drug

Administration of immunosuppressive drugs or immunosuppressants is the main method of deliberately induced immunosuppression. In optimal circumstances, immunosuppressive drugs are targeted only at any hyperactive component of the immune system, and in ideal circumstances would not cause any significant immunodeficiency. However, in essence, all immunosuppressive drugs have the potential to cause immunodeficiency. Immunodeficiency may manifest as increased susceptibility to opportunistic infections and decreased cancer immunosurveillance. The term immunotoxin is also sometimes used (incorrectly) to label undesirable immunosuppressants, such as various pollutants. Polychlorinated biphenyls (PCB) and the insecticide DDT are immunosuppressants.^{[citation needed]} Immunosuppressants may be prescribed when a normal immune response is undesirable, such as in autoimmune diseases.
Cortisone was the first immunosuppressant identified, but its wide range of side-effects limited its use. The more specific azathioprine was identified in 1959, but it was the discovery of cyclosporine in 1970 that allowed for significant expansion of kidney transplantation to less well-matched donor-recipient pairs as well as broad application of liver transplantation, lung transplantation, pancreas transplantation, and heart transplantation. After an organ transplantation, the body will nearly always reject the new organ(s) due to differences in human leukocyte antigen haplotypes between the donor and recipient. As a result, the immune system detects the new tissue as "hostile", and attempts to remove it by attacking it with recipient leukocytes, resulting in the death of the tissue. Immunosuppressants are applied as a countermeasure; the side-effect is that the body becomes more vulnerable to infections and malignancy, much like in an advanced HIV infection.
Throughout its history, radiation therapy has been used to decrease the strength of the immune system. Dr. Joseph Murray of Harvard Medical School and chief plastic surgeon at Children's Hospital Boston from 1972-1985 were awarded the Nobel Prize in Physiology or Medicine in 1990 for his work on immunosuppression.