Question: How does our immune system work?

Kirsty Ross answered on 3 May 2024:

There are two layers to your immune system; the innate and the adaptive.

The innate immune system tends to be non-specific barriers to infection. Snot in your nose is part of that system. The cilia in your lungs that sweeps mucus up into your throat where it can be swallowed is part of that system. We also have immune cells like macrophages, natural killer (NK cells, and mast cells that keep an eye out for problems. It doesn’t remember what your body has seen before, and tends to react in the same way each time.

We also have the adaptive immune system. This system has memory for what your body has seen before, so it can mount an efficient response the next time it sees something, preventing you getting ill. It is made up of cells called dendritic cells, T cells and B cells that live in your tissues and in your lymphatic system. The dendritic cells smash up things that they find (like bacteria, viruses etc) and display bits on their surfaces. These are recognised by T and B cells, who then make lots of copies of themselves. The T cells recognise cells that are infected and can get rid of them. The B cells make something called antibodies that float around your body and stick to the foreign object when they see it again. Some B cells go and live in your bone marrow as memory B cells for the future. It is also the part of the body that is activated each time you have a vaccination.