Immune cells in training to fight cancer

21 November 2018

Every 4 minutes someone in the UK dies of cancer, and the search for more effective treatments is ongoing.

Immunotherapy is one of the most exciting new methods of cancer treatment, and it works by training the body’s own immune system to identify, target, and kill cancer cells. However, because much of the immune system is still a mystery, success rates while using this technique are still quite variable and often depend on the type of cancer being treated. A recent study by Professor Adrian Hayday at the Francis Crick Institute and King’s College London, describes a key discovery that could help improve immunotherapy in the future.

Many immune cells circulate in the blood looking for bacteria or viruses, but one poorly understood type of immune cell sits stationary in certain organs instead. “The big question is why it is that we have; within our body surface tissues, for example, our skin and our gut, literally billions of immune cells called lymphocytes,” said Professor Adrian Hayday, the lead researcher on a study into these cells recently published in Nature Immunology.

He’s referring to T lymphocytes, or T cells - a special type of immune cell. As Professor Hayday explained, these T cells might be scanning the cells it is surrounded by - for example gut cells - and checking that these cells are carrying out their normal jobs properly. Cancer occurs when the DNA of a cell mutates, causing the cell to behave inappropriately and start dividing to make more cells when it shouldn’t. As a result, these ‘scanning’ T cells, which are actively checking on whether a cell is doing what it should, may play an important role in preventing cancer.

Professor Hayday’s lab was interested in studying exactly what these special T cells are doing. Using human gut cells as a model, they found that these T cells use one protein on their cell surface to both check that the gut tissue is behaving as it should, and also to sense when something is going wrong. In other words, these cells have “a unique, unprecedented capacity to really make decisions about whether or not that tissue needs active immunological responses,” said Professor Hayday.

So, what does this have to do with cancer treatment? Well, part of the difficulty of treating cancer effectively is that cancer cells often look a lot like healthy cells. This means that it’s very hard to target just the harmful cancer cells, often leading to side effects like hair loss when patients are going through treatment. However if you can figure out the criteria by which the immune system discriminates between normal and abnormal, Professor Hayday explained “you can potentially engineer that discrimination into, for example, the design of a vaccine to help patients fight their cancers”.

Professor Hayday is hopeful that this would mean the immune system could be boosted to recognise the cancer cells specifically and instructed to eliminate them, while leaving the healthy cells alone. Better immunotherapy could represent a game-changer in cancer treatment for this reason - and with more research, we could have just that.

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