The lymphatic system is part of the immune system. It helps the body fight infections. It also helps maintain fluid balance in different parts of the body. It is made of a series of thin tubes called lymphatic vessels. These vessels collect fluid, called lymph, from different parts of the body. Similar to blood vessels, these vessels then carry the lymph back to the bloodstream. Lymph is a colorless, watery fluid that is rich in white blood cells called lymphocytes. These cells play an important role in the immune system by protecting your body against infection. Lymphocytes form and are stored in lymph nodes, which are pea-sized collections of cells located throughout the body, such as in the armpit, groin, and neck area.
Some organs are also part of the lymphatic system. These include the spleen, thymus, adenoids, and tonsils, as well as the bone marrow:
The spleen is under the lower-left side of your rib cage. It produces lymphocytes, stores healthy blood cells, and filters out damaged blood cells and bacteria.
The thymus is in the front of the chest at the base of the neck. It is central in development of T lymphocytes.
Adenoids and tonsils are areas of lymphoid tissue at the back of the throat. They’re one of the first lines of defense against germs that you breathe in or swallow.
Bone marrow is the inner part of bones. It produces red blood cells, blood platelets, and white blood cells.
The digestive tract also contains lymphoid tissue scattered along its length.
There are two main types of lymphocytes. One type is B lymphocytes, which are also called B cells. The other type is T lymphocytes, which are also called T cells.
The main role of B cells is to protect the body against bacteria and viruses by producing proteins called antibodies. Antibodies attract other immune system cells and proteins that kill bacteria or viruses.
T cells have a variety of functions. Some protect the body by destroying virus-infected cells or by releasing substances that attract other types of white blood cells. Others help destroy some types of cancer cells.
Lymphoma can start in either B cells or T cells. Lab tests can help determine which type of cell the lymphoma has started in by seeing substances on the surface of the cells. Getting this information is an important first step in choosing the best treatment. There are many different types of lymphoma as well as many different types of treatment.