Sunday, May 14, 2006
Humanity's Off Button/Kill Switch
Some human volunteers nearly died during a drug trial. They were testing a monoclonal antibody derivative called TGN1412. It binds to the CD28 T-cell receptor. Basically, this drug, which was given in a very low dose overstimulated the men's immune systems to the point where two of them had multiple organ failure and would have died without life support. Animal and monkey trials showed that the drug was safe even at very high dosages. However, one major difference between human and every other mammal's immune system that we know of is that humans are missing Sialic acid-recognizing Ig-superfamily lectins (Siglecs) on their T-cells. Siglecs seem to moderate the immune response in animals, but since we lack these receptors, our immune system in response to certain challenges turns on into high gear instantly. One take on this is this entry in The Loom.
So what? Big deal. We have immune systems that ramp up quickly and try to kill infectious diseases and maybe kill us in the process if we are unlucky. The one thing Nature hates is overpopulation of a monoculture. Mankind is now a global species. We are spread all over the Earth, turning the planet into an island in space. Almost every spot on the globe can be reached within 24 hours via aircraft from any other point. We are cutting down the rain forests for lumber for building our civilization and rain forests have the greatest biodiversity of any ecosystems on the planet. They also have some of the worst tropical diseases on record. CDC's worst nightmare is an Ebola-like virus being spread by airline across the globe, but now I understand. If we destroy the rain forests, likely some virus or combination of viruses will emerge and will kill us. Just one good plague and the human race is in check again. If it's a fast plague, something that kills in 72 hours or less and is highly contagious, then our public health systems would be unable to cope. So, the lack of Siglecs to moderate our immune systems is our Achille's Heel or "Off Switch" -- Nature's last chance to bring everything back into balance again if we are too stupid to do it ourselves. We and the cheetah have much in common. The cheetahs are dying off in the wild. What about us?
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