Chopping up tonsils

I have been thinking about writing a blog for some time, after all there are only so many hours of the day that can be spent running and baking - particularly as I have chosen not to train for any marathons this spring. The only problem has been deciding how to get started and what to write about. You wouldn't think that would have been such a difficult problem for an Olympic marathon runner with an immunology PhD, but in the end I got the necessary inspiration following a conversation with one of my pool-running friends. We spoke briefly about illness and runners, and I mentioned that I thought it was common for people to pick up infections after running a marathon as the stress of the race lowered their immunity. As I was walking home from the pool I realised that I had never made much of an effort to combine my two interests, and did not really know much about the specifics of the immunological effects of endurance running. A brief search on PubMed and Google revealed that there is actually a society dedicated to exercise and immunology (The International Society of Exercise and Immunology), and their journal seemed like it would provide perfect reading material to inspire my first blog posts.

It turns out that there is rather a lot of reading to be done on the subject of exercise and immunity, and so I'll be saving that for my next post and for now I'll just stick with plain old immunology. I have been involved in a few media interviews since becoming an international athlete, and I have occasionally been asked what exactly my PhD was about. Unfortunately, I have found that condensing over 3 years of scientific research into a few sentences that are understandable by a non-scientist is not an easy job. My default response has therefore been to jokingly say that I pretty much spent my time chopping up human tonsils, and then to add that I was working in a meningitis research lab. That seemed to keep most interviewers happy, but I think that it's now time for me to actually make a real attempt at explaining my PhD for people without a background in biology.

My PhD research was focused on one specific cell type, called dendritic cells, which play a key role in controlling the way our immune system responds to encounters with both harmful and non-harmful foreign material. Dendritic cells are often referred to as the 'sentinels' of the immune system, as their role is essentially to patrol their local environment and assess it for potential danger. The cells constantly sample the material surrounding them, and have receptors which are able to detect the presence of material including components from disease-causing organisms. If a dendritic cell discovers a harmful presence, it alerts another type of immune system cell called a T cell. The T cells then release a variety of signalling factors, which initiate the appropriate immune response to protect against the threatened infection. My research examined how dendritic cells responded to the presence of the Neisseria meningitidis bacteria (one of the leading causes of bacterial meningitis), and how they subsequently interacted with and directed the response of the T cells.

Dendritic cells (DC) detect the presence of potential danger and alert T cells, which then direct the immune system's response.

So why all of the gory chopping up of tonsils? The reason is that the initial site of colonisation by N. meningitidis is in the back of the throat or nose, and the immune tissue closest to this area is the tonsils. This means that the dendritic cells in the tonsils will be among the first immune cells to encounter the colonising bacteria. As tonsils are removed fairly regularly in routine tonsillectomy operations, we had the opportunity to access tissue containing the dendritic cell subset of particular interest to this research. Even though it seems unlikely that anyone would be too attached to their tonsils following removal, we did of course obtain informed consent from the patients or their parents/guardians before conducting any research!