The appendix may be the most underappreciated organ. You can live without it, so people never seem to think it is important. Well, you can live without your spleen, too, but that doesn’t mean it isn’t important. Today, I read that some researchers at Duke Medical School claim to have found a function for the appendix. When I was in grade school, I remember hearing rumors that the appendix was a vestigial organ, whose function was once to grind up rocks that we consumed accidentally. I assume the article isn’t released online yet, and the news story originates from embargoed media information, because I can’t find the primary paper. The article claims that the appendix houses a reservoir of “good” intestinal flora. If the digestive tract becomes depleted of these organisms, for any reason, the appendix can churn out bacteria and reconstitute the entire digestive tract.
As an immunologist, I find this idea particularly intriguing. We have long known that the appendix is composed of lymphoid tissue. However, like most of the GALT (Gut Associated Lymphoid Tissue), we had little understanding about what it was doing. In the past few years, it is becoming more widely accepted that the gut flora are essential to good health (did you remember to eat your yogurt today?). As society becomes more and more sterile, our encounters with many microbes are reduced or eliminated. According to the hygiene hypothesis, this results in an imbalanced immune response prone to allergies, asthma, and inflammatory gut diseases. Our immune system seems to have co-evolved with the environment – it is dependent upon it for proper “education.”
So, this recent finding isn’t all that surprising. It’s just another example demonstrating we still have a lot to learn about how the immune system interacts with the environment—especially the gut.