Question: how does your immune system work?

Carolyn Nielsen answered on 10 Nov 2015:

The immune system is really amazing. I’ve always thought immunology was the most interesting part of science because it’s all about trying to understand the constant battles the immune system has with bugs that are trying to infect you.

Basically the immune system is made up of two parts: the innate immune system and the adaptive immune system.

The innate immune system responds quickly to any pathogen (e.g. bacteria, viruses, fungi, parasites) that it detects inside the body, but it doesn’t have any memory. A cell that is part of your innate immune system will respond in exactly the same way every time it sees, for example, rhinovirus (the virus that causes colds).

The adaptive immune response is made of up of T cells, which can kill infected cells, and B cells, which make antibodies. T cells and antibodies can only respond to specific pathogens, which means they are slower to respond to infections as it takes longer for the right T cells or B cells to find the infection. That’s why the innate system is important as it can, hopefully, keep an infection under control until the adaptive system shows up. But once T cells or antibodies recognise their pathogen, they will make long-term memory cells that stay in the body forever. So next time you get infected with the same pathogen, your adaptive response will be much faster and stronger.

Vaccines work by introducing your immune system to a weak form of a pathogen, which won’t make you sick. This lets your adaptive immune system make these memory cells, so that when you get infected for real, you are protected.

Hope that helps! This is a really good website for an overview of the immune system, run by the British Society for Immunology, if you want more information: http://bitesized.immunology.org/ Or feel free to ask another question, of course!