These are pieces written to desribe what immunolgy is about and what it is like working in science.
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A striking aspect of immune responses is their specificity. Exposure to measles doesn't protect you from chicken pox or vice versa. The influenza virus regularly changes its appearance, and a newly clothed virus can cause an epidemic before the immune response catches up with it. So understanding how the immune system sees things is critical if we want to help it eliminate infection.
One of the most important early observations made about the immune system was that it could recognise anything. To demonstrate this, immunologists exploited the great advances that were being made in the chemistry of dyes. This work had generated whole families of new chemical structures, which had never existed in nature. Immunologists took these novel chemicals and asked whether it was possible for the immune system to learn how to recognise them. And the astonishing answer was that it could.
This finding made it impossible to argue that all an immune system did was remember the diseases it had encountered in the past. Instead, it had evolved an ability to 'expect the unexpected.'
But this is not quite the whole story. We now know that the immune response remembers only a limited amount of information about an infection. It does this by chewing up the invader and taking small digested fragments that it turns into 'antigens.' The rest of the microorganism is ignored. These 'antigens' from the infection are presented to the cells in charge of immune recognition, which remember them and respond in the case of present and future disease. So the recognition of the microorganism is based on only parts of the whole. This provides some diseases such as influenza and malaria an opportunity to dodge the immune system. But it also makes it possible for mistakes in recognition. A chewed up protein from the brain or the eye looks pretty similar to one from a bacteria, and if the immune system makes an error in distinguishing the two, that leads to autoimmune disease.
Lindsay Nicholson.