How Exercise Boosts Immune System To Fight Cancer Cells

November 2, 2020

Cancer patients who exercise generally have a better prognosis than those who don’t. New breakthroughs in research are honing in on exactly how exercise fights cancer on a cellular level. 

The study, conducted at Karolinska Institutet in Sweden, aimed to determine why exercise slows down cancer growth. Numerous other studies have found that exercise activates the immune system but haven’t been able to explain how this happens. If the immune system response is what dramatically slows down cancer growth, what change does exercise create at the cellular level to make this happen? This is the question researchers set out to answer. 

The study was conducted on mice with cancer divided up into two groups, one that trained regularly in a spinning wheel, and another that maintained an inactive lifestyle. As expected, the mice that worked out had slower cancer growth and decreased mortality rates compared to the sedentary mice. Once again, exercise is found to slow the spread of cancer. But why? 

With this finding under their belt, researchers zeroed in on the importance of cytotoxic T cells, white blood cells that specialize in killing cancer cells. They injected antibodies that would remove these T cells from all of the mice, trained and untrained. Without their cytotoxic T cells, exercise no longer had a positive effect on the cancer prognosis among the mice. For the researchers, this confirmed that T cells make all the difference. 

If that wasn’t enough evidence, the researchers even transferred cytotoxic T cells from trained to untrained mice. Just as they had expected, the untrained mice who received those trained T cells suddenly had a new outlook on life. Their prognosis improved, while mice who received cells from untrained animals stayed the same. 

So, cytotoxic T cells are responsible for slowing down cancer, but what about exercise stimulates this response? In order to find out, researchers isolated T cells once again, in addition to blood and tissue samples collected after a training session. They measured the levels of common metabolites produced in the muscles and released into the bloodstream. They found that some metabolites released during vigorous exercise, like lactate, changed the metabolism of T cells and increased activity. This means that exercise trains T cells, making them stronger and more effective. Indeed, T cells taken from trained mice revealed a different metabolism than those taken from rested mice. 

Are you wondering whether these findings are relevant to our human bodies? Good question. They are. When researchers analyzed blood samples from eight healthy men after 30 minutes of robust exercise, they saw that the same metabolites were released. This is good news for our own T cells. Exercise is just as important to humans as it is to mice. 

With so much going on in the world right now, it is helpful to focus on the things we can control. You have the power to choose exercise. And it’s a wise choice, as the results of this study show that regular exercise is the first step toward a long and healthy life. Helene Rundqvist, senior researcher and author of the study, says, “We hope these results may contribute to a deeper understanding of how our lifestyle impacts our immune system and inform the development of new immunotherapies against cancer.” 

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