Words you will meet in the guides

Coming from another person. In an allogeneic, or donor, transplant, the stem cells come from a relative or an unrelated volunteer whose cells are a close enough match to the patient's.

A protein made by the immune system that sticks to one specific target, such as a germ. Some wrongly target the body's own tissues. Lab-made antibody medicines can target markers such as CD20 or CD38 on some cancer cells.

Coming from the patient's own body. In an autologous transplant, the patient's own stem cells are collected and stored, then given back after high-dose treatment. It does not use a donor.

A type of white blood cell that makes antibodies. B cells are part of the immune system and grow from stem cells in the bone marrow. Some lymphomas and leukemias start in B cells.

Young blood cells that have not finished developing. In leukemia and some related diseases, abnormal blasts build up in the marrow and blood and leave less room for healthy blood cells. Doctors count blasts to help identify the disease.

Young cells that can grow into every type of blood cell: red cells that carry oxygen, white cells that fight infection and platelets that help blood clot. They are found in the bone marrow and the bloodstream.

The soft, spongy tissue in the center of most bones. Red bone marrow holds the blood-forming stem cells that make red blood cells, white blood cells and platelets.

A treatment that takes a patient's own T cells, changes them in a lab so they can find and attack cancer cells, then gives them back through a vein. Standard CAR-T therapy does not use a donor.

Someone with one changed copy of a disease gene who has no symptoms or only mild ones. A carrier can pass the change to a child. A child with a changed copy from each parent usually has the condition.

Having cells with two or more different sets of DNA in one body. After a donor transplant, a person has a mix of their own DNA and DNA from the donor's transplanted cells. Genetic tests can find this mix.

A research study that tests how well a new medical approach works in people. Trials can test new ways to screen for, prevent, diagnose or treat a disease.

Treatment that prepares a patient for a stem cell transplant. It can include chemotherapy, radiation or antibody medicines. It makes room in the marrow for the new cells, helps prevent rejection and can kill cancer cells.

More testing after a registry donor is shortlisted as a possible match. The donor's blood sample confirms their HLA markers and is checked for infections. It helps the care team choose the most suitable donor.

Blood collected from a newborn baby's umbilical cord after birth. It contains many blood-forming stem cells, so donated cord blood can be used for a stem cell transplant.

One donated collection of cord blood. If it holds enough blood-forming stem cells, it is frozen and stored until a patient needs it. It is listed on a registry so patients searching for a match can find it.

White blood cells (lymphocytes) from the same donor, given some time after a donor transplant. They may kill cancer cells that are left. It is used for some cancers, such as chronic myeloid leukemia (CML) that has come back.

When stem cells given in a transplant settle in the bone marrow and start making new white cells, red cells and platelets. It usually happens within 2 to 4 weeks. The cells may come from a donor or the patient.

Treatment that gives a lab-made copy of an enzyme the body lacks. It drips slowly into a vein (infusion) on a set schedule. It can help some organs in certain storage disorders, but standard forms do not reach the brain.

Treatment that adds a new gene or restores the work of a faulty or missing one. For some inherited disorders, the patient's own blood-forming stem cells are changed in a lab and given back. It does not use a donor.

The blood-forming stem cells given to a patient in a transplant. In a donor transplant, the graft comes from the donor's bone marrow or blood, or from donated cord blood.

When donor stem cells never start making enough blood cells after a transplant, or start and then stop. Blood counts stay low or fall. It has many possible causes. An immune attack on the new cells (graft rejection) is one.

A complication of a donor transplant. The donated cells see the patient's healthy tissues as foreign and attack them, especially the skin, liver and gut. It can start soon after transplant or much later and can be life-threatening.

When immune cells from a donor transplant attack the patient's cancer cells. The donor cells may come from bone marrow or blood.

Half-matched. A haploidentical donor's tissue type (HLA) matches about half of the patient's. It may be a parent, child, brother or sister. Care teams may use one when a fully or closely matched donor is not available.

Very strong drug treatment given in large doses, often to kill cancer cells. It also destroys the bone marrow and can cause other serious side effects. A stem cell transplant usually follows to rebuild the marrow.

Markers on most cells that make up a person's tissue type. Doctors test a patient's and donor's HLA to see how well they match. The more markers they share, the better the chance the body accepts the donor's cells.

A lab test that finds a person's tissue type (HLA markers). It starts with a blood draw or a cheek swab. Doctors compare a patient's results with those of relatives, registry donors and cord blood units.

Treatment that lowers the activity of the immune system. It can calm an immune attack on the body, as in aplastic anemia, or help keep the body from rejecting a transplant. It also makes infections harder to fight.

A very small number of cancer cells left in the body during or after treatment. Only very sensitive lab tests find them. Some can spot one cancer cell among a million normal cells. Testing is used mostly in blood cancers.

When blood-forming cells from both the donor and the patient are found after a donor transplant. In blood cancers, it can be a warning sign of relapse. In some non-cancer diseases, a steady mix can still work well.

Strong enough to destroy the bone marrow. Myeloablative chemotherapy is high-dose treatment that kills marrow cells, including cancer cells. A stem cell transplant usually follows to rebuild the marrow.

A group of cancers in which the bone marrow does not make enough healthy blood cells and abnormal cells appear in the blood or marrow. Also called myelodysplastic syndromes (MDS). Sometimes they turn into acute myeloid leukemia.

Having to do with the bone marrow, or with certain blood-forming cells made there. Also called myelogenous. Acute myeloid leukemia (AML) is a fast-growing cancer that starts in these cells.

A type of white blood cell that is one of the first to respond to germs such as bacteria. Low neutrophil levels raise the risk of serious infection.

Tests for serious conditions, often done before a newborn baby leaves the hospital. Some use a few drops of blood from the baby's heel. If a result points to a condition, more tests check for it.

Blood that flows through the body. For transplants, stem cells can be collected from this blood instead of the bone marrow. A medicine first moves stem cells from the marrow into the blood; then a machine collects them.

Tiny pieces of cells in the blood that help form clots to slow or stop bleeding. They are made in the bone marrow. Too few platelets can cause easy bruising and bleeding.

A way to help prevent graft-versus-host disease. The chemotherapy drug cyclophosphamide is given in high doses a few days after the donor cells, often on days 3 and 4. Its use grew with half-matched donors and now includes matched ones.

Lower doses of chemotherapy or radiation given before a donor transplant. They do not wipe out the marrow but calm the immune system enough to accept donor cells. It may be an option for older or less healthy people.

Describes a disease that does not respond to treatment. It may resist treatment from the start, or treatment may stop working along the way.

When a disease comes back after a period of getting better. Relapsed disease has returned after treatment helped for a time.

A decrease in or disappearance of the signs of a disease. In complete remission, no signs can be found, but some disease cells may still be in the body.

A treatment that gives a patient healthy blood-forming stem cells through a vein. The cells travel to the bone marrow and replace faulty marrow or marrow damaged by treatment. They can come from the patient or a donor.

Medicine taken by mouth that slows how much of a fatty substance the body makes, so less builds up. It is used for some adults with Gaucher disease type 1. Enzyme replacement therapy, by contrast, supplies the missing enzyme.

Affecting the whole body. Systemic treatment uses medicines that travel through the blood to reach cells all over the body.

A type of white blood cell that is part of the immune system. T cells grow from stem cells in the bone marrow, help protect the body from infection and may help fight cancer.

Medicines designed to act on specific molecules involved in a disease. In cancer, they target molecules that cancer cells need to survive and spread. Some block signals that tell cancer cells to grow; others help the immune system kill them.

Putting blood, or parts of blood such as red cells or platelets, into a person's bloodstream through a vein. Some people with blood disorders need regular transfusions.