The lymphatic system is a major component of the body's immune system.
Lymphocytes are the cells that attack bacteria in the blood.
Lymph nodes are small, bean-shaped, soft nodules that are not usually visible or easily felt. They are located in clusters in various parts of the body, such as the neck, armpit, and groin. Lymph nodes produce lymphocytes, monocytes, and plasma cells. They also filter the lymph fluid and remove foreign material, such as bacteria and cancer cells. When bacteria are recognized in the lymph fluid, the lymph nodes enlarge as they produce and supply additional white blood cells to help fight infection.