USS Clueless              Voyages of a restless mind

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Stardate 20010818.0950 (On Screen): The engineering miracle we call the human body isn't really quite the miracle. It's a bit flawed in places, more of a "good enough" design than an elegant one. (I've written about that before.) One of the most complex and comprehensive and important systems in our bodies is our immune systems, and it is trying to solve an extremely tough problem, because it has to improvise. No other system in our body improvises except our brains. The immune system has to differentiate three cases: uninfected "self" cells, infected "self" cells and foreign cells. The latter two are attacked and destroyed when detected, which isn't always possible. But it's important that it only destroy cells which can be replaced, which is why it largely ignores the nervous system. It also can only detect infected "self" cells if they have a structure called an endoplasmic reticulum (try saying that three times fast), which lets out red blood cells.

Certain white cells have a sort of genetic toolbox of perhaps a thousand fragments of DNA. When they detect a foreign cell (means unknown) they work on piecing together those fragments in different ways (mechanism unknown) until they figure out how to produce an antibody specific to that invader. Once they determine that they've successfully done this (evaluation mechanism unknown) then they reproduce like mad and start pouring out millions of antibodies. The antibodies attach themselves to infected self cells and to invaders, and this acts as a signal to other white cells which engulf and destroy the tagged objects. As you can see, there are many things about this that we don't understand yet.

Also, it is imperfect. Antibodies attach to what are known as antigens and the system is designed under the assumption that the antigen is stable. That isn't actually the case. In some viruses, the genes which describe the antigens which our immune systems recognize are very unstable and mutate easily. As a result, during the war new viruses will appear having different antigens, and the immune system treats these new ones as a separate disease and starts the recognition process from scratch. Also, it's possible for a disease to hide from the immune system, which is why some diseases become chronic. Herpes and papilloma (which causes warts) hide in the nerves, and periodically come out for a rematch, which is why you'll suffer attacks from them all your life.

But the worst thing of all is that sometimes the immune system goes too far and begins to attack uninfected self cells. The result is what are called "autoimmune diseases" and some of them are quite surprising. Lupus is one, and it is extremely unpleasant. In Multiple Sclerosis, the immune system forgets itself and begins to attack nerves in the body, especially in the spinal column. Depending on the progression of the disease this can paralyze or even kill. Even stranger is type 1 diabetes. This appears to have both genetic and environmental aspects; according to current theory, the genetic factor makes the child have a reaction to something in his food, which makes his immune system activate and as a side effect it attacks and destroys all the cells in the pancreas which ordinarily would secrete insulin. (Work is underway to try to determine what it is that they're reacting to. If found, it might mean that type 1 diabetes could be prevented in susceptible children by dietary control, which would be quite exciting.)

It's long been suspected that a tumor is actually a symptom of the disease we call "cancer", not actually the disease itself. Of course, that "symptom" is what kills us, but attempting to treat tumors directly isn't necessarily dealing with the underlying cause, and doesn't really provide any clue towards prevention. Much progress has been made, but cancer is a puzzling disease. New research is strongly suggesting that cancer may actually be an immune system malfunction, a negative side effect of long term hyperstimulation of the immune system. One reason this is exciting is that it may permit creation of a test to identify vulnerable individuals even before development of tumors, which would mean that those people could be much more closely monitored to catch tumors early (when treatment is most effective). But even more exciting is the possibility of developing a treatment which could be given to such people to prevent development of tumors entirely. (discuss)