Lymphocyte

A Lymphocyte is a small white blood cell that plays a major role in defending the body against disease. There are two main types of lymphocytes: B cells, which make antibodies that attack bacteria and toxins, and T cells, which attack body cells themselves when they have been taken over by viruses or become cancerous.

Sources[edit]

http://www.genome.gov/glossary.cfm?key=lymphocyte