Norovirus might have laid you low for a short while, but you’re recovering, aren’t you? Your immune system is to die for. Researchers are still getting to grips with how it works but at every turn it has thrown out marvellous surprises. In the early days of vaccination against tuberculosis, for example, it was noted that it protected you not only from TB, but a host of other diseases, too.
We still don’t know why; it’s clear that we have yet to understand the full power of the human immune system. Just in December, for instance, we learned that the system’s T-cells, which fight viruses and bacteria, are not all created equal. Almost all of our knowledge of human T-cells has come from blood samples. But research using T-cells harvested from the organs of New York cadavers has shown that each region of the body has its own particular way of fighting invaders. Columbia University’s Donna Farber, who led the study, believes this discovery may open up the path to tightly focused vaccines that can activate the most appropriate of the body’s immune responses.
Her optimism is supported by another surprise the immune system has just delivered. New Scientist reported this month that there is now hope for a vaccine against age-related macular degeneration (AMD), an incurable condition that blinds millions of people around the world.
AMD comes from the build-up of proteins and other debris on the retina. In healthy people this is cleared away by specialist cells. Those cells stop working in people with AMD. This appears to have two consequences: the build-up of debris continues and the light-sensitive cells of the retina beneath the debris start to die off. The result is a slowly widening black hole at the centre of your field of vision.
Pioneering treatments with a laser can stimulate the nonfunctioning cells to get them going again, which is exactly what Robyn Guymer of the University of Melbourne was trying to do in his trial on 50 patients. The idea was to try the laser treatment in one eye and leave the other eye as a control. Then tests on each eye would show what improvements the procedure could give.
So, you could imagine it was a little frustrating that in the tests the lasered eye didn’t seem to be that much better than the one that had been left alone. But Guymer soon realised this was because the vision of the untreated eye had also improved. The laser surgery had stimulated the patients’ immune system to respond to alarm calls from the eye.
Your eyes are usually offlimits to your immune system. It seems a sensible evolutionary trick, because the immune system’s standard response causes inflammation, which could be catastrophic in an instrument as sensitive as the eye. However, the cells destroyed by the laser appear to send out a signal so loud that the immune system overrides the safety mechanism and sends in the troops – to both eyes – to restore order.
There is now hope that AMD can be treated with a routine procedure at a very early stage, and that those most at risk of developing it can have their immune systems stimulated before the symptoms appear. But there is a wider lesson: with various successes in vaccines against cancer – particularly colon cancer – looking likely in the next few years, it’s becoming clear that the most profitable path for medicine might be to explore partnerships with the remarkable abilities that already lie within us.
Michael Brooks’s “The Secret Anarchy of Science” is published by Profile Books (£8.99)