Clear and colorless, the interstitial fluid bathes and surrounds the cells of the body and is a means of supplying materials to the cells. How to define it? What is its role and its composition? What is the difference with lymph?

The lymphatic system is the collection of vessels and lymph nodes that carry a fluid called lymph and help the body defend against infections and keep cells running smoothly in a fluid called interstitial fluid.

Interstitial fluid is the fluid that occupies the space between blood capillaries and cells. It is from this liquid that cells get their food and oxygen and facilitate the exchange of nutrients and waste between them. The excess interstitial fluid is drained by the lymphatic capillaries and becomes, the lymph.

Cells are made up of water, amino acids, sugars, fatty acids, coenzymes, hormones, neurotransmitters, salts, and cell products.

For the proper functioning of the cells to be ensured, this medium must have a stable composition and volume. Every day, just over 10 liters of fluid leaks out of the blood capillaries and becomes part of the interstitial fluid. It is the lymphatic system which is responsible for harmonizing the balance by bringing excess interstitial fluid back into the bloodstream. The excess called lymph has a major role in cleaning waste from the body and in the fight against infectious agents.

The lymph nodes, resembling nodes on the lymph path, serve as a filter and quickly trigger immune defense reactions.

The lymphatic system brings back to the blood proteins which are in the interstitial fluid and which cannot easily pass through the wall of the blood capillaries because of their too large size. The lymphatic vessels transport lipids, which have been ingested in the small intestine, to the liver.

The lymph can be affected by different pathologies:

• Non-Hodgkin lymphoma : cancer that starts in the lymphatic system. Usually, it starts in the lymph nodes, hence its name “cancer of the lymph”. Symptoms are an increase in lymph node size that can be felt, unexplained fever, severe night sweats and weight loss;
• Hodgkin lymphoma (or Hodgkin’s disease) is a form of cancer of the lymphatic system and characterized by an abnormal increase in the volume of lymphocytes;
• Le lymphœdème : manifests itself by the retention of interstitial fluid (lymph) when it cannot circulate normally because of an obstacle and causes swelling (edema) of the surrounding soft tissues, often located in the extremities, also called lymphatic obstruction. When the lymph nodes have been removed or damaged due to cancer then the risk of lymphedema increases with the number of lymph nodes affected;
• Lymphangitis: infection of one or more lymphatic vessels, usually due to bacteria (case of erysipelas) and results in a red, swollen and painful course of the lymph vessel in question with an increase in the volume of the lymph node.

La lymphoscintigraphy is the examination that allows you to visualize the lymphatic system.

The formal diagnosis of non-Hodgkin lymphoma and Hodgkin lymphoma is based on:

• determining the shape of the lymphoma, which requires a lymph node biopsy, that is to say the removal of a sample of tissue from one of the abnormal nodes;
• the extension assessment which aims to find all the locations of the disease;
• the general assessment of the patient in order to assess the other pathologies that may be present, in particular cardiac, and to determine the possible treatments.

The diagnosis for lymphedema: The iympho-MRI “is more and more practiced in the diagnosis, when the diameter of a limb is greater than that of the opposite limb, also more effective to identify a slowing down of the circulation. lymphatic.

The diagnosis for lymphangitis : The typical appearance and blood tests usually show an increase in the number of white blood cells that fight infection.

For these different pathologies, here are the treatments offered:

• Non-Hodgkin lymphoma : chemotherapy, radiotherapy and immunotherapy are part of the treatments depending on the type and stage of lymphoma, as well as other factors;
• Hodgkin lymphoma : chemotherapy is the first-line treatment;
• Le lymphœdème : there is no curative treatment. If it is early, decongestant physiotherapy is effective in reducing swelling and relieving symptoms;
• Lymphangitis : it is treated most of the time with antistreptococcal antibiotics.