Allogeneic Stem Cell Transplantation | The Leukemia …

Allogeneic stem cell transplantation involves transferring the stem cells from a healthy person (the donor) to you after high-intensity chemotherapy or radiation.

Allogeneic stem cell transplantation is used to cure some patients who:

Allogeneic stem cell transplantation can be a high-risk procedure. The high-conditioning regimens are meant to severely or completely impair your ability to make stem cells. You may experience side effects during the days you receive high-dose conditioning radiation or chemotherapy. Specifically, high-conditioning therapy's goals are to:

The immune system and the blood system are closely linked and can't be separated from each other. Because of this, allogeneic transplantation means that not only the donor's blood system but also his or her immune system is transferred. As a result, these adverse effects are possible:

The immune reaction, or GVHD, is treated by giving drugs to the patient after the transplant to reduce the ability of the donated immune cells to attack and injure the patient's tissues. See Graft Versus Host Disease.

Allogeneic stem cell transplants for patients who are older or have overall poor health are relatively uncommon. This is because the pretransplant conditioning therapy is generally not well tolerated by such patients, especially those with poorly functioning internal organs. However, reduced intensity allogeneic stem cell transplants may be an appropriate treatment for some older or sicker patients.

One goal of allogeneic stem cell transplant is to get the T lymphocytes in the donor's blood or marrow to take hold (engraft) and grow in the patient's marrow. Sometimes the T lymphocytes attack the cancer cells. When this happens, it's called graft versus tumor (GVT) effect (also called graft versus cancer effect). The attack makes it less likely that the disease will return. The effect is more common in myeloid leukemias than it is in other blood cancers.

Unfortunately, T lymphocytes are the same cells that cause graft versus host disease (GVHD). Because of this serious and sometimes life-threatening side effect, doctors in certain cases want to decrease the number of T lymphocytes to be infused with the stem cells. This procedure, called T-lymphocyte depletion, is currently being studied by researchers. The technique involves treating the stem cells collected for transplant with agents that reduce the number of T lymphocytes.

The aim of T-lymphocyte depletion is to lessen GVHD's incidence and severity. However, it can also cause increased rates of graft rejection, a decreased GVT effect and a slower immune recovery. Doctors must be careful about the number of T lymphocytes removed when using this technique.

Stem cell selection is another technique being studied in clinical trials that can reduce the number of T lymphocytes that a patient receives. Because of specific features on the outer coat of stem cells, doctors can selectively remove stem cells from a cell mixture. This technique results in a rich number of stem cells and fewer other cells, including T lymphocytes.

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