Immune and lymphatic systems

Your immune system is a system of cells, tissues and organs that protect your body from infection, by finding and killing germs, bacteria or viruses.

White blood cells called B lymphocytes, T lymphocytes and neutrophils play an important role in fighting infections.

Blood cancer can stop your immune system from working properly, meaning you can get more infections than normal, and infections can become more serious.

This can happen for various reasons:

• If the cancer affects your bone marrow, your body can’t produce enough healthy white blood cells.
• If the cancer affects your white blood cells, they do not develop and work properly.
• If you have large numbers of abnormal (cancerous) blood cells, there isn’t enough room left for healthy white blood cells to grow and work.
• Cancerous blood cells can build up in the lymphatic system and stop that working properly (see below).
• Some treatments for blood cancer also damage your healthy white blood cells.

We have more information on understanding infection and reducing your risk.

Your lymphatic system is part of your immune system and also helps protect you from infection.

It’s made up of a network of thin tubes called lymph vessels, which connect lots of glands throughout your body called lymph nodes.

A fluid called lymph travels through the lymphatic system. It contains lots of lymphocytes (a type of white blood cell that fights infection).

Lymph nodes sometimes trap bacteria when you have an infection. When lymph nodes are fighting the infection, they often swell and feel sore.

Your spleen is also part of your lymphatic system. It filters blood that passes through it, and also contains white blood cells that fight infection.

Blood cancer can affect your lymphatic system if large numbers of abnormal (cancerous) blood cells begin to build up in your lymph nodes or spleen, causing swellings. This build-up of cells can stop your lymphatic system from working properly, meaning you are more at risk from infections.