White blood cells are one of the components of our blood, along with red blood cells, platelets and plasma. Each of these components has a unique function in our body and in medicine.
White blood cells are continuously made in our bone marrow. They have a short lifespan of just one to three days.
The medical term for these cells is leukocytes. There are several different types of cells, including granulocytes, monocytes and lymphocytes.
White blood cells help our bodies defend against disease in three ways:
Unfortunately, they can also cause harm to a person who receives donated blood. That’s because they may carry viruses that cause immune suppression and release toxic substances. To avoid these problems, white cells are often removed from donated blood and blood components before the donation is given to a patient.
Granulocytes are the most common type of white blood cell. They protect against infection by surrounding and destroying invading bacteria. Unlike other types of white cells, they do play an important medical role: they can be used to treat infections that don’t respond to antibiotics.
These cells make up about 1% of the total volume of our blood. A person is considered to have a normal white blood cell count if they have between 4,500 and 11,000 white blood cells per microliter of blood. Or in more familiar measurements, that’s around 17 – 40 million white blood cells per teaspoon of blood!
Granulocytes are the only type of white blood cell that the Red Cross collects. Since granulocyte must be used within 24 hours, donations are only taken when a specific patient needs them. To be eligible to donate granulocytes, you must have donated platelets
Our ability to provide lifesaving granulocytes to patients depends on having a steady supply of platelet donors. Every 15 seconds someone needs platelets – that’s about 2 million units of platelets being transfused each year in the U.S. Making a platelet-only donation means you help people who need platelets now, and may be able to help someone who needs granulocytes in the very near future!