Because I have the flu, I have been thinking about the immune system, and what an under-appreciated system it is. By which I do not mean that we should throw it a party with cake to thank it for all the hard work it's been doing. I mean, rather, that we are profoundly ignorant of what that work is and how we can facilitate it.

Most people go their entire lives without realizing the existence of the lymphatic system, and few people have any sort of detailed knowledge about it. Even I, well on my way to a PhD in biology, have only a cursory understanding of how it operates. The spleen is a completely baffling organ; almost no one can tell you what it does. Compare this to the circulatory system, where the names of individual veins and arteries are relatively common knowledge. And there's very little understanding of what governs the health of the immune system. We all know what sorts of foods are bad for our heart and will clog our arteries; we know what will make us fat, what will be bad for our liver, what makes our colon happy. What's good for the immune system?

I suppose this is understandable in a society that has basically eviscerated disease - things that were killer plagues in previous centuries are unknown today, and almost no one is really worried about dying of infectious disease the way they are worried about cancer and the like. Even for the obvious exceptions (e.g. AIDS), the immune system is not the protagonist. We're looking out for efficient molecular weapons to deliver a precise and artificial cure; no one ever imagines their own bodies will protect them.

This ignorance is unfortunate for something we depend so vitally on, the more so because it is such a fragile guardian, so easily turned against us. I'm somewhat haunted by the idea that we're bathing ourselves in a chemical soup - detergents, preservatives, lubricants, pigments, deodorants, varnishes, insecticides, etc., etc. - with no idea of what it is doing to our immune systems. Every time I hear that increasingly common story about how someone's kid has some strange new allergy, I have to wonder whether we're not screwing ourselves up in unimagined ways.

People always make a big hoop-la over carcinogens. But carcinogenicity is well-studied. It's well-understood. It's one of the few things that actually gets tested for. No one has any clue about auto-immune disease, or immunodeficiency. It's not even on the map.

I've ended on rather a more somber note than I intended, unfortunately. But on the other hand, I seem to be convalescing, and I can take some comfort in the fact that MY immune system is performing quite well. So even though I don't have any idea what it is, I'm evidently doing something right.