White blood cells (WBCs), also known as leukocytes, are an essential component of the immune system, serving to protect the body from harmful microorganisms.
When an infection develops in the body, the number of white blood cells quickly increases, and the cells are transported to the infection site to attack and destroy the bacteria, virus, or other “bug” causing it.
There are five types of white blood cells that circulate in the blood:
The concentrations of each can fluctuate on a day-to-day basis. Each type has a specific role and function. For more information on the individual types, check out these links:
Measuring the number of the different white blood cells in the body is useful for diagnosing infections and other diseases. This blood test is called white blood cell differential test, and it calculates the number of each WBC type as well as the total WBC count.
All white blood cells are measured in micrograms per liter (mcg/L)