Explainer: how does the immune system learn?

When the innate response fails to deal with an invasion, the adaptive immunity takes over. The adaptive cell looks for a specific pattern. It could be a particular protein on the surface of a virus or bacteria.

There are millions of adaptive immune cells, each to recognize a different pattern. When they recognize an invader, they multiply to form an army to kill it. This process can take a week when a new invader infects us. After the invader is removed, the adaptive cells that recognized it are kept as specialized memory cells.

Innate immune cells are changed by previous infections or vaccination through trained immunity.

Because innate learning changes innate immune cells, infection by one invader can change how the immune system deals with a completely different invader.

Studies suggest the immune learning is strongly affected by environmental factors, like diet, lifestyle, surroundings, and previous infections.

But this provides hope that we can improve immunity and reduce disease through environmental factors.