Introduction A white blood cell (WBC) count is a test that measures the number of white blood cells in your body. White blood cells, also called leukocytes, are an important part of the immune system. They originate in the bone marrow but move throughout the bloodstream. These cells help fight infection by attacking bacteria, viruses, and germs that invade the body.
Principle The principle behind a white blood cell count is to measure the number of white blood cells in your body to detect hidden infections within your body and alert doctors to undiagnosed medical conditions, such as autoimmune diseases, immune deficiencies, and blood disorders. This test also helps doctors monitor the effectiveness of chemotherapy, radiation treatment, and other therapies in people with cancer.