Plateletpheresis: In plateletpheresis, a donor gives only platelets rather than whole blood. Whole blood is drawn from the donor, and a machine that separates the blood into its components selectively removes the platelets and returns the rest of the blood to the donor. Because donors get most of their blood back, they can safely give 8 to 10 times as many platelets during one of these procedures as they would give in a single donation of whole blood. Collecting platelets from a donor takes about 1 to 2 hours, compared with collecting whole blood, which takes about 10 minutes.

Autologous Transfusion: In an autologous transfusion, donors are recipients of their own blood. For example, in the weeks before undergoing elective surgery, a person may donate several units of blood to be transfused if needed during or after the surgical procedure. The person takes iron pills after donating the blood to help the body replenish the lost blood cells before surgery. Also, during some types of surgery and in certain kinds of injuries, blood that is lost can be collected and immediately given back to the person (intraoperative blood salvage). An autologous transfusion is the safest type of blood transfusion, because it eliminates the risks of incompatibility and blood-borne disease.

Controlling Diseases by Purifying the Blood In hemapheresis, blood is removed from a person and then returned after fluid, substances in the fluid, blood cells, or platelets are removed or reduced in quantity. Sometimes, this process is used to obtain needed blood cells or platelets from a donor (for example, stem cell pheresis or plateletpheresis). This process is also used to purify blood by removing harmful substances or excessive numbers of blood cells or platelets in people with serious illnesses who have not responded to other treatments. To be helpful for purifying blood, hemapheresis must remove the undesirable substance or blood cell faster than the body produces it. The two most common types of hemapheresis that are used to purify blood are plasmapheresis and cytapheresis. In plasmapheresis, harmful substances are removed from the plasma. Plasmapheresis is used to treat such disorders as myasthenia gravis and Guillain-Barré syndrome (neurologic disorders that cause muscle weakness), Goodpasture's syndrome (an autoimmune disorder involving bleeding in the lungs and kidney failure), pemphigus vulgaris (severe, sometimes fatal, blistering of the skin), cryoglobulinemia (a type of abnormal antibody formation), and thrombotic thrombocytopenic purpura (a rare clotting disorder). In cytapheresis, excess numbers of certain blood cells are removed. Cytapheresis can be used to treat polycythemia (an excess of red blood cells), certain types of leukemia (a type of cancer in which there are excess white blood cells), and thrombocythemia (an excess of platelets). Hemapheresis is repeated only as often as necessary, because the large fluid shifts between blood vessels and tissues that occur as blood is removed and returned may cause complications in people who are already ill. Hemapheresis can help control some diseases but generally does not cure them.

Directed or Designated Donation: Family members or friends can donate blood specifically for one another if the recipient's and donor's blood types and Rh factors are compatible. For some recipients, knowing who donated the blood is comforting, although a donation from a family member or friend is not necessarily safer than one from an unrelated person. Blood from a family member is tested as are all blood samples and then treated with radiation to prevent graft-versus-host disease, which, although rare, occurs more often when the recipient and donor are related.

Stem Cell Pheresis: In stem cell pheresis, a donor gives only stem cells (undifferentiated cells that can develop into any type of cell) rather than whole blood. Prior to the donation procedure, the donor receives an injection of a special type of protein (growth factor) that stimulates the bone marrow to release stem cells into the bloodstream. Whole blood is drawn from the donor, and a machine that separates the blood into its components selectively removes the stem cells and returns the rest of the blood to the donor. Stem cell donors must be compatible with recipients by lymphocyte type (human leukocyte antigen, or HLA), a type of protein found on certain cells, rather than blood type. Stem cells are sometimes used to treat people with leukemia, lymphoma, or other cancers of the blood. This procedure is called stem cell transplantation. The recipient's own stem cells can be obtained, or donated stem cells can be given.

Last full review/revision July 2007 by Harold S. Kaplan, MD; Donna L. Skerrett, MD