I have just returned from a network meeting on structures inside cells, in Cambridge. I thoroughly enjoyed it. It was quite wide ranging and including a lot of quite diverse stuff going on inside our cells, and included a talk on part of our immune system.
Our immune system is phenomenal, it is astounding complex, and does remarkable things. It has been honed into a scarily complex fighting machine by hundreds of millions of years of evolution, to fight infectious organisms that have been evolving for even longer.
We kind of take it for granted that our immune system can fight infection, but that is not all trivial. We have fancy labs to identify bacteria using sophisticated analysis, but of course our immune systems do not have that luxury. Our immune system can identify bacteria from small fragments of alien bacterial proteins that these invaders have produced. The immune system distinguished these small fragments from the countless fragments of our proteins inside our bodies.
These protein fragments are tiny, a few billionths of a metre across, but the immune T cell’s can spend 20 minutes radically restructuring most of their insides as they attempt to decide if a handful of peptides are alien or belong to us. These T cells are tens of millionths of metres across, thousands of times larger than the tiny protein fragments. This large scale internal rearranging seems like overkill but it is very important to get identification right. Our immune system needs to identify infectious bacteria, unchecked they can kill us. But if our immune system misidentifies our own cells as alien, then the result is autoimmune diseases like rheumatoid arthritis.
Marvelling at our immune system is thirsty work, so after dinner we went to the The Eagle, notable as the pub where Francis Crick announced that he had discovered the structure of DNA. They serve the Titanic brewery’s Plum Porter, which really does taste of plums, I can recommend it.
Chance & Necessity 