What do white blood cells do?
White blood cells are part of the immune system. They defend the body against infections by finding and destroying bacteria, viruses and other invaders.
There are several types of white blood cells, each with a different job. Neutrophils, the most common, rush to infections and swallow bacteria. Lymphocytes include B cells, which make antibodies, and T cells, which kill infected cells and coordinate the immune response. Monocytes become macrophages that clean up debris.
White blood cells are made in the bone marrow and travel through the blood and lymphatic system. They make up only about 1 percent of blood. When you have an infection, your body makes more of them. Swollen lymph nodes during an illness are a sign that white blood cells are busy fighting.
Memory of the immune system
Some B and T cells become memory cells after an infection. They remember the invader and respond quickly if it returns, which is why you usually catch diseases like chickenpox only once. Vaccines work by training these cells without causing the disease.
Did You Know?
Pus, which forms at infected wounds, is made largely of dead white blood cells that fought the infection.
This answer is general information, not medical advice. For a personal health question, talk to a doctor.