What is Acute Rejection?

Most organ transplants, unless they are from one identical twin to another, are expected to cause acute rejection in the recipient. This stage begins approximately a week after a transplant has occurred, or later, and is the body’s immune response to the foreign tissue. Even when a transplant is a good match, the body still views the new organ as foreign, and the immune system alerts the body to attack it. This is generally manageable with transplant drugs that shut off the immune system attack. With this measure, acute rejection is usually ended, though it can recur and its likelihood of recurrence means it’s absolutely important to pursue regular follow-up visits and report any health concerns to doctors.

Acute rejection sounds very serious to some people, and the term can often be misleading because of its name. Actually, it should be noted that this form of rejection is expected. It would be serious if there were no way to control it, because the body’s ability to attack the transplanted organ would lead to its failure.

Fortunately, this form of rejection is often easily controlled with drugs. Should acute rejection occur again, additional medications could be used. The more serious and usually incurable form of rejection is called chronic, and this creates inflammation that cannot be controlled. Chronic rejection leads to full rejection of the organ; a rejection that is acute is, in contrast, frequently manageable.

The specific action of acute rejection is mostly due to slight mismatches in proteins called human leukocyte antigens (HLA). In some cases, like for bone marrow donation, HLA between a donor and receiver is precisely matched. For most organ donations and transplants, people have minor differentiations in the DNA sequences that produce these proteins. The body recognizes these slight differences, and a particular group of white blood cells called T-lymphocytes or T cells assaults the foreign tissue. Uninhibited T cells break down the tissue of the transplanted organ (lysis) and stop its function.

The T cells cannot understand that their attack of the new organ is life-threatening to the body, so they need to be disabled. Certain medications accomplish this, turning off T cell and other immune system responses so that acute rejection quickly ends or is prevented. These medicines certainly have side effects and make people more vulnerable to viral, fungal, and bacterial infections. Care is needed to balance avoiding rejection with rendering a person unable to fight infection. Tremendous research and refinement continues to go into creating medications that have the lowest burden of side effects and that prevent or cure acute rejection.

It can’t be overstated that people with transplants require regular follow-up care with physicians. Evidence of acute rejection recurring needs to be treated right away so that organ or other tissue function is undamaged. Transplant patients are advised to contact their doctors any time they notice unusual health changes.