A blood differential test measures the amount of each type of white blood cell (WBC) that you have in your body. White blood cells (leukocytes) are part of your immune system, a network of cells, tissues, and organs that work together to protect you from infection. There are five different types of white blood cells:
- Neutrophils are the most common type of white blood cell. They are your body's main defense against infection when bacteria, viruses, or other germs enter your body.
- Lymphocytes include two main types of white blood cells: B cells and T cells. B cells fight off invading viruses , bacteria , or toxins. Certain T cells can target and destroy your body's own cells, such as cancer cells and cells that have been infected by viruses.
- Monocytes kill bacteria, viruses, and other germs that may make you sick. They also boost your body's immune response and clear away dead cells.
- Eosinophils defend against parasites and infections. They are also involved in allergies and help control inflammation (swelling and redness).
- Basophils release enzymes during allergic reactions and asthma attacks.
However, your test results may have more than five numbers. For example, the lab may list the results as counts as well as percentages.
Other names for a blood differential test: Complete blood count (CBC) with differential, Differential, White blood cell differential count, Leukocyte differential count