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Term Glossary

Select a letter from the menu to see a list of terms that begin with that letter.

A| B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

A

Absolute Neutrophil Count: A measure of the actual
number of mature neutrophils present in the blood per unit
volume.

Allergen: A substance that causes an allergic reaction.

Anemia: Any condition in which there are too few red
blood cells in the bloodstream, resulting in insufficient
oxygen to tissues and organs.

Antigen: Protein present on the surface of cells that can
stimulate an immune reaction.

Aplastic: Involving the absence or defective development
of a tissue or organ.

Acquired: Any condition that is not genetic (inherited) or
congenital (present at birth); usually caused by
environmental factors and/or physical conditions.

Autologous: Involving the patient serving as his/her own
donor, especially in transfusions and bone marrow
transplants.

B

Band: An immature neutrophil.

Basophil: A type of white blood cell that plays a role in
allergic reactions.

Blast Cells: Immature cells that mature into the three
types of blood cells.

Bone Marrow: Soft tissue occupying the inner cavities of
bones responsible for blood cell production.

Bone Marrow Aspiration: A medical process in which a
small amount of bone marrow is extracted through a needle
inserted into the back of the hip.

Bone Marrow Biopsy: A medical process in which an intact
piece of marrow is removed for study

C

Cellularity: The quantity, quality, or condition of cells
present in the bone marrow.

Cytokines: Hormone-like proteins secreted by many
different cell types to regulate cell proliferation and
function.

Cytomegalovirus: A widespread opportunistic virus that
can cause disease in an immunosuppressed person

Cytopenia: A deficiency of cells in the blood.

Cytotoxic: Destructive to cells.

D

Differentiate: To become distinct or specialized; acquire
a different characteristic or function than the original.

E

Engraftment: When bone marrow infused during a bone
marrow transplant is accepted by the patient's body and
begins producing blood cells.

Enzyme: A protein that acts as a catalyst to induce
chemical changes in other substances.

Eosinophil: A type of white blood cell that kills parasites
and plays a role in allergic reactions.

Erythrocyte: A mature red blood cell.

F

FAB criteria: Criteria for classifying leukemia and
myelodysplastic syndromes developed and agreed upon by
a group of French, American and British scientists.

Febrile: Involving an elevated body temperature; feverish.

G

Granulocyte: Any one of these three types of white blood
cells: neutrophils, eosinophils, and basophils; so called
because they have granules that contain enzymes to help
fight infection.

H

Hematocrit: The percentage of a volume of blood
occupied by red blood cells.

Hematologist: A doctor who specializes in the study of
blood and blood-producing organs

Hematopoiesis: The process of blood cell production.

Hemochromatosis: An excess of iron deposits in the
body, also known as iron overload.

Hemoglobin: The red blood cell protein-iron compound
responsible for transporting oxygen from the lungs to the
cells, and carbon dioxide from the cells to the lungs.

Hereditary: Refers to any condition passed via genes
from parent to child

Hyperplastic: Involving an increased number of cells.

Hypersensitivity: An abnormal sensitivity to a stimulus.

Hypoplastic: Involving a decreased number of cells.

I

Idiopathic: Refers to any condition with no known cause.

Immunosuppressive: Being capable of inhibiting immune
responses.

Iron Chelator: A substance that binds iron and then
eliminates it from the body in the urine and stool.

L

Leukocyte: White blood cells, important in defending
against infection and clearing the body of harmful material
(see also granulocytes, monocytes and lymphocytes).

Lymph: A clear, transparent filtrate of plasma that is
collected from tissues throughout the body and eventually
flows to the lymphatic system.

Lymph Node: see Lymphatic System

Lymphatic System: The tissues and organs (including
the bone marrow, spleen, thymus and lymph nodes) that
produce and store cells that fight infection and the network
of vessels that carry lymph.

Lymphocyte: A type of white blood cell that directs the
body's immune response; divided into two forms, B cells
and T cells.

M

Megakaryocyte: A large cell in the bone marrow from
which platelets are formed.

Monocyte: A type of white blood cell that plays a role in
immune and inflammatory responses

Morphology: The study of the structure and form of an
organism or one of its parts

N

Neutropenia: A deficiency of neutrophils in the blood.

Neutrophil: The most numerous of the white blood cells,
important for helping the body fight infections (see also
bands and stabs).

P

Packed RBCs: A concentrated blood product in which
plasma has been removed from the blood to make
transfusions easier and faster (also called PRBCs).

Pancytopenia: A deficiency of all types of blood cells.

Petechiae: Pinpoint hemorrhagic spots in the skin.

Pathophysiology: Functional changes in the body that
are associated with or result from disease or injury.

Petechiae: Small red or purplish spots on the skin or a
mucous membrane, caused by very small hemorrhages

Phagocytosis: The process by which white blood cells
(specifically neutrophils) engulf and destroy
microorganisms or cells.

Plasma: The fluid (noncellular) portion of circulating blood.

Platelet: The smallest blood cell, essential for blood
clotting. Also called thrombocyte.

PMN: A mature neutrophil.

Poly: A mature neutrophil.

Proliferation: Growth by reproduction of similar cells.

R

Reticulocyte: An immature red blood cell normally
restricted to the bone marrow and present in the
bloodstream only in very low numbers.

Reticulocytosis: A condition in which there is an increase
in the number of circulating reticulocytes.

S

Seg: A mature neutrophil.

Stab: An immature neutrophil.

Stem Cells: Cells that are produced in the bone marrow
and differentiate into red cells, white cells, and platelets

Subcutaneous: Beneath the skin.

T

Thrombocyte: Platelet.

Thrombocytopenia: A decrease in the number of
platelets in the blood, resulting in the potential for
increased bleeding and decreased ability for clotting.

T-lymphocyte: A type of lymphocyte that is important in
the immune response, but in aplastic anemia suppresses
the stem cells; also known as a T cell lymphocyte.

Transferrin: A protein that binds with iron and thus
regulates iron absorption and transports iron in the body.

Transfusion: The process by which blood or one of its
components is delivered directly into the bloodstream

U

Unrelated Donor: A donor that is not a sibling or other
familial relation of the patient (recipient).

V

Vital Signs: A person's temperature, pulse, respiration, and
blood pressure