Sunday, March 27, 2016

Using "Incompatible" Kidneys for Transplant

Every year, hundreds of patients who need a new kidney die before a donated kidney (either from a living person or a cadaver) can be found for them. The basic problem is that the donated kidney has to be a good immunological match for the recipient (the patient) or his/her immune system will attack the donated kidney, ultimately causing it to be rejected. But before we blame the immune system for this problem, remember that the immune system protects us from infectious diseases precisely because it attacks foreign tissues and cells, such as bacteria.

Knowing how the immune system works, scientists think they may have found a way to circumvent the system so that any kidney could be used in any recipient. It would mean that a husband could donate to his wife, for example, or any friend could donate to a friend in need. This would be a huge advance, because the chance of a good immunological match between two unrelated individuals is around one in 100,000 or more.

In the procedure, called "desensitization", the patient's antibodies are filtered out of the blood. (They're replaced by an infusion of other antibodies to provide some temporary protection from infection.) After the kidney transplant, the patient's immune system slowly replenishes the patient's own antibodies, but for some reason these new antibodies are not as likely to attack the foreign (donated) kidney.

  According to a recent summary study, the 8-year survival rate of desensitized patients who received an incompatible kidney was 76%. That compares favorably to the 44% survival rate of a matched group of control patients who simply remained on the transplant list.

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