​​Understanding How Immunity is Maintained in Healthy People​

Summary

​​​Healthy immune function depends on having the right number of white blood cells in the body. There are many different types of white cells, with different functions. They are kept in balance by a process of continual replacement with newly-made white cells. We are investigating how this works by giving people a tracer to drink which measures the number of newly-made cells. The tracer is called ‘heavy water’. It is a form of water which has a slightly different structure from normal water. It is harmless, is not radioactive, and occurs naturally in the environment and in your body.  

​We are using this approach to better understand how a specialist immune cell called a gamma-delta cell is kept in balance in healthy young and older people. People who take part drink a small dose of heavy water every day for 7 weeks. We take three blood samples during this period, then five more over the next three months. From these samples, we take the gamma-delta cells, and measure the amount of heavy water they contain. From this we can work out how they are regulated in the human body. These measurements will help us understand how healthy immunity is maintained.​