T cells are on the front lines of the immune system, monitoring the body for pathogens, and springing into action when those invaders are identified. All that work requires fuel, and T cells take up nutrients for power. New research has shown that T cells can use some surprising sources to get the energy they need, even stuff that has long been thought to be discarded from cells as waste products. The findings, which have been reported in Cell Metabolism, may one day help scientists develop dietary recommendations that can be tailored for individual patients of cancer or other diseases, suggested the researchers.
"Every process in the body is powered by metabolism, which in turn is fueled by the nutrients we consume through our diet. We found that immune cells are much more flexible in selecting the nutrient fuels they consume and, importantly, that they prefer some nutrients that were previously dismissed as waste," said senior study author Russell Jones, Ph.D., Chair of Department of Metabolism and Nutritional Programming at the Van Andel Institute..
"This understanding is crucial for optimizing T cell responses and developing new strategies for boosting our ability to fight off disease," Jones added.
Like many other types of cells that are cultured in the lab, T cells are grown in a dish that contains nutrient-rich liquid or media. But this environment is not a very good replication of the environment in the body, which contains many other molecules. For this study, the researchers used a cell media that was enriched with a wide array of nutrients.
Immune cells that have been studied in laboratories have been living on a basic diet, which would be like a person subsisting on eggs and toast, Jones said. But when the cells got a "full buffet" in this study, the investigators found that the cells preferred a more diverse diet than we knew.
For example, lactate is thought of as a waste product, and when it's released after a workout, it can cause muscle aches. But T cells actually seem to prefer lactate over other common sugars like glucose. When given both lactate and glucose, T cells used lactate as fuel, and seemed to function more efficiently when they did so.
Lactate is also produced by cancer cells, and actually aids their ability to attack other tissues and evade the immune system.
"This has major implications for how we tailor dietary recommendations as ways to promote health and combat disease," said Jones.
While some research has indicated that high lactate levels may harm T cells, this study has suggested that lower levels of lactate may be beneficial to T cells.
The function of T cells may be significantly affected by the nutrients that are available to them. Jones and colleagues are planning to follow up on this work to learn more about how metabolism may impact immunity.