White Blood Cells (Leukocytes)
What are white blood cells?
White blood cells, or leukocytes, are part of the body's immune system, where there is one white blood cell for every 600 to 700 red blood cells. The white blood cell's main function is to help fight infections. Most of our white blood cells are individualized to our specific bodies, which is why white blood cells are removed from transfusable blood. Removing the white blood cells from transfusable blood is known as leuko-reduction, which prevents the blood from causing a negative reaction during donation.
There are five main types of white blood cells:
Lymphocytes: Help the body make cells that fight against infection and make antibodies.
Monocytes: Help other white blood cells to remove damaged tissue and gobble up bacteria, viruses, debris and infectious organisms.
Eosinophils: Kill parasites, destroy cancer cells and help the immune system with an allergic response.
Basophils: Release histamine if there is an allergic reaction; help prevent blood clots.
Neutrophils: Help heal damaged tissue and resolve an infection.
How are White Blood Cells Used?
The list of white blood cells mentioned is broken up into two categories: granulocytes and agranulocytes. The agranulocytes are the lymphocytes and monocytes. The granulocytes include eosinophils, basophils and neutrophils.
Currently, the Red Cross collects granulocytes to help treat infections that don't respond to antibiotics. This process is known as apheresis and the cells must be transfused to the patient within 24 hours of donation. Donated granulocytes are collected on an as-needed basis. To be eligible to donate granulocytes, you must have donated platelets through the Red Cross within the past 30 days.
What are platelets?
Platelets, or thrombocytes, are tiny blood cells that can only be seen under a microscope. They are made from the spongy center inside our bones known as bone marrow. Platelets typically live for about 8 to 10 days in our body. A platelet's main function is to rush to an injury in the blood vessel and form a plug to fix the damage. This plug is known as a clot, or thrombus, which helps prevent blood loss.
However, there are conditions where the body may produce too little or too many platelets. Too many platelets are known as thrombocythemia, where there is excessive clotting. When there are too few platelets in the blood this is known as thrombocytopenia, where bruising and abnormal bleeding become more likely.
How Are Platelets Used?
Because platelets help control bleeding, they are mainly used for cancer treatments, organ transplants, surgeries, and platelet dysfunctions. Platelets can be extracted from a whole blood donation using a centrifuge or they can be collected using an automated process. This process allows, one donor to contribute four to six times as many platelets as platelets collected from a whole blood donation. And because platelets need to be used within five days of donation, there is a constant need for platelet donors!