Lymphoma and the immune system

How does lymphoma affect the immune system?

Lymphoma is a type of blood cancer that develops when white blood cells called lymphocytes grow out of control. Lymphocytes are part of your immune system. If you have lymphoma, your immune system might not work as well as it should for several reasons:

• The lymphocytes that grow out of control don’t work properly. If you have too many of these abnormal lymphocytes and not enough healthy lymphocytes, your body can’t fight infections as well as usual. You might pick up infections more easily, and they could be more severe or last for longer than they would normally.
• If you have lymphoma cells in your bone marrow, they take up space that is normally used to make healthy blood cells, including white blood cells that fight infections. This might mean your body can’t make enough white blood cells to protect you from infection.
• Cancer cells, including lymphoma cells, use up your body’s energy. This can affect your immune system’s ability to work well. It can also cause weight loss and loss of muscle mass.

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How does treatment for lymphoma affect the immune system?

Treatment for lymphoma aims to kill lymphoma cells. However, it can also damage healthy cells. Cells in your immune system are particularly sensitive to the effects of cancer treatments. This is why many people have a lowered immune system during, and for a while after, treatment for lymphoma.

Your immune system should recover over time after your treatment finishes, but it might be lower than usual for several months. The speed of recovery depends on the specific treatment you have received.

Effects of treatment on your immune system

Many chemotherapy drugs damage your bone marrow, where your blood cells develop. This can lead to low blood counts. In particular, you might develop low levels of white blood cells called neutrophils (neutropenia). Neutropenia increases your risk of infection.

Stem cell transplants have a greater effect on the immune system than most other treatments. This is because they involve very high doses of chemotherapy, and sometimes radiotherapy. If you have a stem cell transplant using donor cells (an allogeneic stem cell transplant), you also have drugs that dampen your immune system to stop the donor cells attacking your own cells. These make your immune system very low. It can take a year or more to recover.

Steroids are often given as part of lymphoma treatment to help fight the lymphoma and to reduce side effects. However, they also lower your immune system. This can increase your risk of infections, particularly viral infections (such as cold sores or shingles) and fungal infections (such as thrush).

Antibody therapies and targeted drugs fight lymphoma using your own immune system. They aim to destroy lymphoma cells, but they can affect healthy lymphocytes too, especially B lymphocytes.

Occasionally, some people with lymphoma might need an operation to remove their spleen (a splenectomy). Having no spleen can increase your risk of infection with certain bacteria. If you’ve had a splenectomy, it is important to stay up-to-date with specific vaccinations. Most people who’ve had a splenectomy take long-term, low-dose antibiotics to help prevent infections.

Other ways treatment can affect your immune system

As well as white blood cells, your immune system includes physical barriers to help stop germs getting into your body. Some procedures or treatments for lymphoma can affect these barriers, which might increase your risk of infection. This can include:

• chemotherapy or radiotherapy, which can damage your skin or the lining of your mouth, making it easier for germs to enter
• injections or blood tests, which pierce your skin and can provide a point of entry for germs
• having a peripherally inserted central catheter (PICC line) or central line fitted, which can give bacteria a route into your bloodstream
• surgery, including biopsies, which create a break in your skin that can allow germs into your body.

Your medical team take great care to avoid introducing infections when performing any procedures. They also regularly check lines and wounds and keep them clean.

Tell your medical team if you notice any signs of infection, such as redness, swelling or pain at the affected area.

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Using the immune system to treat lymphoma

Some lymphoma treatments use your immune system to help treat the lymphoma. These include:

• Antibody therapy, which uses man-made antibodies to flag up lymphoma cells and tell your immune system to kill them. Antibody therapy is used to treat many types of lymphoma, usually in combination with chemotherapy. This is known as ‘chemo-immunotherapy’.
• Stem cell transplants using donor cells (allogeneic stem cell transplant). The donor stem cells build a ‘new’ immune system. The new immune cells can recognise lymphoma cells as foreign and help to get rid of them.
• Targeted treatments that help your immune system to recognise and attack lymphoma cells (such as checkpoint inhibitors).
• CAR-T cell therapy, where your own T cells are genetically modified (changed) in a laboratory to recognise lymphoma and kill lymphoma cells.

Many of these treatments are already available for some types of lymphoma, and more are being tested in clinical trials. To find out more about clinical trials, or to search for a trial that might be suitable for you, visit Lymphoma TrialsLink.

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