Every day, your body’s immune system protects you from legions of invaders that attempt to infiltrate your body. A major part of your immune system is the lymph system.
The lymph system is made up of lymph fluid, a network of organs, lymph nodes, lymph ducts, and lymph vessels that circulate lymph fluid to tissues and the bloodstream. Lymph nodes and lymph vessels are part of the circulatory system. In addition to playing a part in immunity, the lymph system transports excess fluid and fat.
Lymph is a colorless, watery fluid that originates as blood plasma. It seeps from the small blood vessels, or capillaries, to bring nutrients to cells and transport waste from the cells. Most of the plasma immediately returns to the circulatory system, but some does not. This leftover fluid, which carries proteins, bacteria, and other substances that are too large to be absorbed by the capillaries of the veins in the circulatory system, is collected by the lymphatic vessels. The lymph vessels carry the fluid to lymph nodes in the neck, armpit, groin, abdomen, chest, and spleen, where bacteria, cancer cells, and other potentially harmful particles are collected to prevent them from entering the bloodstream. If the usually soft and small lymph nodes collect a large number of bacteria or other harmful molecules, or respond to a viral infection, they become enlarged and often can be felt. The cleaned lymph returns to the bloodstream.
Lymph carries white blood cells, chiefly lymphocytes that destroy foreign material and diseased cells. The two main types of lymphocytes are B cells and T cells. Both are made in the bone marrow and circulate in the blood, but they are also in the thymus, spleen, lymph nodes, and tonsils. B cells make antibodies. T cells attack body cells that have been infected by viruses or have become cancerous.
Besides following a healthy lifestyle—eating right, exercising regularly, and getting enough sleep—you can also boost your immune system's efficacy by making sure you have the proper immunizations, including tetanus and influenza. Immunizations increase the range of antigens the immune system recognizes.