What is Graft vs. Host Disease?

Graft vs. Host Disease (GvHD) is a reaction that develops after an allogeneic bone marrow transplant. An allogeneic transplant is one in which the donor is not the same person as the recipient. It is also possible to have your own bone marrow cells harvested and transplanted back into you, if you are scheduled to have a treatment that will damage them. This is called an autologous bone marrow transplant.

Bone marrow cells are a major component of the immune system. In GvHD, the transplanted cells see the recipient’s body as foreign. The grafted cells then attack their new host. This is how the condition got its name.

GvHD is extremely common after bone marrow transplantation. However, it usually goes away after the transplant has become well established in your body.

There are two forms of graft vs. host disease: acute and chronic.

Acute GvHD

Acute GvHD occurs within weeks of receiving a bone marrow transplant. It is usually the result of the donor’s stem cells and bone marrow not matching the recipient’s. It is important for the human leukocyte antigen (HLA) in both the donor and recipient to match. Otherwise, the donor’s bone marrow views the recipient’s cells as foreign and attacks them. Recipients who receive mismatched bone marrow are at the highest risk of developing this condition. However, GvHD can occur even with proper HLA matching.

Acute GvHD normally affects the skin, liver, and gastrointestinal system.

Chronic GvHD

Chronic GvHD develops over a longer course of time than acute GvHD. Its underlying cause is the same as acute GvHD. However, the reaction is less severe.

People with chronic GvHD may not develop symptoms for several months. Sometimes, symptoms do not show up for several years. Chronic GvHD can affect any area of the body.

GvHD most commonly occurs in patients with leukemia who have undergone a bone marrow transplant.

Leukemia is a form of cancer that begins in the cells of the bone marrow. The bone marrow is the sponge-like area of bone where blood cells are produced. In patients with leukemia, the bone marrow grows uncontrollably. This leads to an influx of white blood cells often with a reactive deficiency of red blood cells. While many treatments exist, Leukemia can be a life-threatening condition.

People with certain forms of leukemia may require a bone marrow transplant when other types of treatment fail. Types of leukemia that are treated with bone marrow transplants include:

  • acute lymphocytic leukemia (ALL)
  • chronic myeloid leukemia (CML)
  • acute myeloid leukemia (AML)

The exact cause of GvHD isn’t always clear. However, researchers agree that several risk factors increase the likelihood of GvHD. The biggest risk factor for GvHD is an HLA mismatch between the recipient and donor. This can cause both chronic and acute GvHD.

Other risk factors for acute GvHD include:

  • age differences between the recipient and donor
  • sex differences between recipient and donor
  • receiving bone marrow from a woman who had been pregnant within the previous year

The primary risk factor for chronic GvHD is having a history of acute GvHD.

When the bone marrow cells from the donor begin to attack the recipient’s cells, symptoms may occur in several of the body’s systems.

Skin symptoms commonly affecting those with acute GvHD include:

  • rash
  • itching
  • dark patches or darkening of the skin

Gastrointestinal symptoms include:

  • nausea
  • vomiting
  • diarrhea
  • abdominal cramping

Liver symptoms include:

  • yellowing of the skin and eyes (jaundice)

Eye symptoms include:

  • dryness
  • irritation
  • itching

If you have recently had a bone marrow transplant and are experiencing any of these issues, contact your doctor.

If you are a bone marrow transplant recipient with symptoms of GvHD, talk to your doctor as soon as possible. During your visit, tell your doctor about all of your symptoms, no matter how minor they may seem.

If your doctor suspects you have GvHD, you will receive a blood test. This test will look for high levels of white blood cells, which usually indicate an infection.

If your test shows a high white blood cell count, you may need a tissue biopsy. The biopsy is usually performed while you are under sedation. It can also be performed with just a local anesthetic. A small piece of tissue will be removed from the area affected by GvHD. It will then be sent to the lab and tested for abnormalities.

In many cases, a urinalysis (urine test) will also be used to detect signs of infection. Urine tests can be used to rule out conditions such as diabetes or bladder infections.

The primary treatment for GvHD is prescription immunosuppressants. These drugs reduce the immune response of the donor cells. They are usually prescribed in the form of intravenous or oral steroids.

Glucorticoids are often used to treat acute GvHD, along with the following medications:

  • antithymocyte globulin
  • denileukin diftitox (Ontak)
  • infliximab

Corticosteroids are often prescribed to treat chronic GvHD, along with the following medications:

  • daclizumab
  • etanercept
  • infliximab

Preemptive treatment with immunosuppressant medications may reduce the risk of GvHD after transplantation. These drugs are usually started before the transplant. Your doctor may recommend that you continue to take them for several months after the transplant is complete.

About a year after your bone marrow transplant, your body may enter a “state of tolerance.” At this point, immunosuppressive medications are less necessary.

At one year, most recipients will have formed new T lymphocytes that match the donor cells. These matching cells keep the donor marrow from attacking the recipient’s cells.

People who do not enter a state of tolerance may need to continue taking immunosuppressants for a longer period of time.