Mobilized white blood cell donation is a specialized procedure that collects white blood cells (leukocytes) from a healthy donor. Unlike standard blood donations, it requires preparing the donor to produce more of these cells before collection. The collected white blood cells provide a temporary immune boost to patients whose own immune systems are severely compromised. It offers a targeted therapeutic intervention for individuals facing life-threatening conditions.
Understanding White Blood Cells and Mobilization
White blood cells (leukocytes) are a diverse group of cells that form a major part of the body’s immune system, protecting against infections and foreign invaders. They are produced in the bone marrow from hematopoietic stem cells and circulate throughout the bloodstream and lymphatic system. Different types of white blood cells, such as neutrophils, lymphocytes, and monocytes, each have specialized functions, including engulfing bacteria, producing antibodies, and coordinating immune responses.
Mobilization is a preparatory step to increase white blood cells in the bloodstream, making them more accessible for collection. This is achieved by administering medications like granulocyte-colony stimulating factor (G-CSF) for several days before donation. G-CSF is a synthetic hormone that stimulates the bone marrow to produce and release more white blood cells into the blood. Sometimes, a steroid like dexamethasone may also be given to enhance the release of these cells into circulation. This mobilization ensures a sufficient quantity of white blood cells can be collected during the donation process.
The Donation Process
Donors undergo a thorough medical evaluation to ensure suitability and safety for the procedure. This screening includes a review of health history, a physical assessment, and blood tests. Once eligible, the donor starts mobilization medication, typically G-CSF, administered as daily injections for four to five days leading up to the donation. Some protocols may also include an oral steroid, like dexamethasone, the evening before donation to further boost white blood cell counts.
On the day of donation, collection occurs through apheresis. During apheresis, the donor is seated, and blood is continuously drawn from one arm, passed through an apheresis machine, and then returned to the other arm. This machine separates blood into its components, collecting white blood cells (granulocytes) while returning red blood cells, platelets, and plasma to the donor. The procedure usually takes three to five hours, as the donor’s blood is circulated through the machine multiple times to collect a sufficient volume of white blood cells, typically around 400 mL.
Donor Considerations
Donors undergo a comprehensive screening process to determine their eligibility. Donors must be in good health, at least 17 years old, and weigh a minimum of 110 pounds (50 kilograms). Medical staff inquire about recent illnesses, medications, and travel history, and conduct a physical assessment including temperature, blood pressure, and pulse checks. Conditions such as a history of diabetes, tuberculosis, or peptic ulcers may affect eligibility.
Donors should be aware of potential side effects from mobilization drugs and apheresis. G-CSF injections commonly cause bone or muscle pain, particularly in the sternum, pelvis, and lower back, due to increased blood cell production. Other symptoms include headaches, fatigue, and sometimes nausea or diarrhea. These side effects typically begin one to two days after starting medication and usually subside within about a week after donation.
Serious side effects like splenic rupture are exceedingly rare (estimated at 1 in 5,000 to 1 in 10,000 cases), but donors are monitored for discomfort. Apheresis generally has a low complication rate, but minor issues like tingling around the lips and fingers due to the anticoagulant (citrate) are possible and can be managed by staff. Bruising at the needle insertion site, dizziness, or fainting can also occur.
Who Benefits from These Donations
Mobilized white blood cell donations provide a targeted immune boost to patients facing severe immune deficiencies. Patients with a low white blood cell count (neutropenia) due to myelosuppressive chemotherapy or bone marrow transplants are common recipients. These patients are susceptible to life-threatening bacterial or fungal infections that are difficult to treat with antibiotics alone.
Donated granulocytes help these vulnerable patients fight existing infections and reduce their risk of developing new ones. Patients with aplastic anemia, a condition where the bone marrow does not produce enough blood cells, including white blood cells, may also benefit from these transfusions. In these situations, the transfused white blood cells act as a temporary defense, bridging the gap until the patient’s own immune system can recover or a more permanent solution, such as a stem cell transplant, can take effect.