White Blood Cells (WBC, Leukocytes)

White blood cells are part of the body's immune system. They help the body fight infection and other diseases. Types of white blood cells are granulocytes (neutrophils, eosinophils, and basophils), monocytes, and lymphocytes (T cells and B cells). Your white blood cells account for only about 1% of your blood, but their impact is big.

The normal number of WBCs in the blood is 4,500 to 11,000 WBCs per microliter (4.5 to 11.0 × 109/L). Normal value ranges may vary slightly among different labs.

White blood cells are produced by your bone marrow to help your body fight infection. With a low white blood cell count and, in particular, a low level of neutrophils, you're at higher risk of developing an infection. And if you develop an infection when you have a low white blood cell count, your body can't protect itself. When you have a low white blood cell count, your immune system isn't working as well as it should.

Vitamin C is thought to increase the production of white blood cells, which are key to fighting infections. This is why most people turn straight to vitamin C after they've caught a cold. That's because it helps build up your immune system.

What happens if white blood cells are high?

A high white blood cell count may indicate that the immune system is working to destroy an infection. It may also be a sign of physical or emotional stress.