Good evening everyone,
At the end of this week we find ourselves in the midst of a discussion of immune function, first with our lecture yesterday on the immune system (Chapter 7), to be followed by our next lecture on infectious disease (Chapter 8), scheduled for next Monday.
Recall that for tomorrow's class (Friday 20 Sept), we will not meet in person. Instead, I'd like you to read/digest a news article on a current and very relevant immune topic, that of environmental exposure to antigens.
For much of the history of our species, human life and society was based around agriculture, including exposure to domesticated animals. In the last hundred years, of course, that has changed for many, as populations became more urban. During this same period, the use of cleansing and sanitizing products in the household has increased dramatically, culminating recently in the explosion of "anti-bacterial" products, such as soaps, wipes, and tissues.
Most immunologists believe that we have taken cleanliness a bit too far. According to the "hygiene hypothesis", natural exposure to antigens keeps the immune system primed for action, and enables it to make robust responses to actual disease agents. In our ultra-clean worlds, however, many (especially the young children of cleaning-obsessed parents) are coming into contact with fewer and fewer natural antigens, and increasingly their immune systems are ill-equipped to respond to them when they do, leading to a rash (no pun intended) of allergies, sensitivities, or, at worst, autoimmune disorders.
This article explores the "hygiene hypothesis" and some of its implications. As you go through it, I'd like you to consider a few key questions:
- what happens to our immune system when we are exposed to naturally-occurring antigens?
- why should exposure to non disease-causing antigens enable us to better respond to more serious antigens?
- do you personally use anti-bacterial products in your household?
- does this article make you want to reconsider their use, in any way?
Our immune system is wonderfully complicated and powerful, but some think that our social behaviors have evolved faster than is good for it. Perhaps a nice walk outdoors, a swim in a lake, or a picnic in the grass is just what we need...
Have a great weekend - see you on Monday.