Wow VERY information Dr. Kalra MD! Thank you!
Hi, Acute rejection - although this can happen at any time after the transplant, most often it happens during the first several months. This can be treated by giving you higher doses of medication by mouth or by intravenous infusion. You may get this treatment as an outpatient if it is recognized early.
Chronic rejection - this may happen months or years after the transplant. This type of rejection is resistant to treatment with current medications. This will cause your new organ to slowly stop working
Acute rejection usually begins one week after transplantation (as opposed to hyperacute rejection, which is immediate). The risk of acute rejection is highest in the first three months after transplantation. However, acute rejection can also occur months to years after transplantation. A single episode of acute rejection is not a cause for concern if recognised and treated promptly, and rarely leads to organ failure.
Tissues such as the kidney or the liver which are highly vascularized (rich in blood vessels), are often the earliest victims of acute rejection. In fact, episodes of acute rejection occur in around 60-75% of first kidney transplants, and 50 to 60% of liver transplants. Damage to the endothelial lining of blood vessels is an early predictor of irreversible acute transplant rejection.
The reason acute rejection usually begins one week after transplantation is that T-cells are involved in the rejection mechanism. These T-cells must differentiate before rejection begins. The T-cells cause cells in the transplanted tissue to lyse, or produce cytokines that cause necrosis of the transplanted tissue.
http://en.wikipedia.org/wiki/Transplant_rejection
http://www.kidneytransplant.org/patientguide/rejection.html