Lymph system

The lymph system is a network of organs, lymph nodes, lymph ducts, and lymph vessels that produce and transport lymph from tissues to the bloodstream. The lymph system is a major component of the body’s immune system.


Lymph is a clear-to-white fluid made of:

  • chyle (fluid from the intestines after digestion that contains proteins and fats)  
  • some red blood cells  
  • many white blood cells, especially lymphocytes (lymphocytes are the cells that attack bacteria in the blood)

Lymph nodes are small, bean-shaped, soft nodules. They 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 immune cells (such as 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 additional white blood cells to help fight infection.

The organs within the lymphatic system are the tonsils, adenoids, spleen, and thymus.

See also:


Johns Hopkins patient information

Last revised: December 7, 2012
by Mamikon Bozoyan, M.D.

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