The lymphatic system is part of the body’s immune system. It helps to protect us from infection and disease.

What is the lymphatic system

The lymphatic system is part of the body’s immune system. It helps to protect us from infection and disease. The lymphatic system also drains fluid from the body’s tissues back into the blood.

A diagram showing the network of lymph nodes throughout the body:

The diagram shows the network of lymph nodes throughout the body. There are nodes in the neck (cervical), armpit (axilla) and groin (inguinal). There are also lymph nodes in the chest and abdomen. The diagram shows the thymus gland at the top of the chest area, and the spleen, which is on the left side of the abdomen. The diagram also shows the diaphragm, which is the muscle that separates the chest from the abdomen.

The lymphatic system includes:

  • lymph vessels
  • lymph nodes (sometimes called lymph glands)
  • lymphocytes (blood cells that fight infection)
  • lymphatic organs
  • other lymphatic tissue.

Lymph vessels are fine tubes that form a network inside the body. A clear fluid called lymph moves through the vessels and nodes and eventually returns to the bloodstream.

There are groups of lymph nodes around the network. As the lymph fluid passes through the nodes, they filter out disease and germs (bacteria and viruses). The lymph nodes contain infection-fighting white blood cells called lymphocytes. Lymph nodes often swell when they are fighting infection. If you have a throat infection, you may be able to feel swollen lymph nodes in your neck below your jaw.

Lymphatic organs

Lymphatic organs include the thymus, which helps some types of lymphocytes to mature. They also include the spleen and the tonsils, both of which help fight or filter out disease and germs.

The bone marrow is the spongy material in the middle of bones. It makes:

  • all the different types of white blood cell including lymphocytes
  • red blood cells, which carry oxygen from your lungs to other cells in your body
  • platelets, which help blood to clot and prevent bleeding and bruising.

There are also other areas of lymphatic tissue where lymphocytes and other infection-fighting cells collect. These areas are mostly found where disease or germs are more likely to enter the body – for example, in the lining of the bowel, lungs and nose.

About our information

  • References

    Below is a sample of the sources used in our lymphoma information. If you would like more information about the sources we use, please contact us at

    Eichenauer DA, et al on behalf of the ESMO Guidelines Committee. Hodgkin's lymphoma: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Annals of Oncology. 2014. 25 (Supplement 3): iii70-iii75. Available at:


    Ladetto M et al. ESMO consensus conference on malignant lymphoma: general perspectives and recommendations for prognostic tools in mature B-cell lymphomas and chronic lymphocytic leukaemia. Annals of Oncology. 2016. 27: 12, 2149-2160. Available at:


    National Institute for Health and Care Excellence (NICE). Guideline NG47. Haematological cancers: improving outcomes. 2016. Available at:


    National Institute for Health and Care Excellence (NICE). Guideline NG52. Non-Hodgkin’s lymphoma: diagnosis and management. 2016. Available at:

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editors, Dr Anne Parker, Consultant Haematologist; and Professor Rajnish Gupta, Macmillan Consultant Medical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.