There are two main types of lymphocytes, known as B cells and T cells (also known as B lymphocytes and T lymphocytes). The B cells produce antibodies that attack foreign molecules (germs and the toxins they produce). The T cells are more complicated, but they can attack the body’s own cells when they are diseased (for example, when the cells have been invaded by cancer or viruses).
Substances secreted by lymphocytes (called lymphokines) contribute to inflammation. Wherever there is chronic inflammation in the body, lymphocytes are present.