How do we develop immunity?

Immunity is the ability for the body to respond to familiar pathogens so quickly that they are not able to cause a physical disease, meaning we can be infected for a short period of time, and not notice. To do this the body needs to be able to recognise pathogens that have previously infected us. This is achieved by ‘lymphocytes’, a particular kind of white blood cell, that recognise ‘antigens’; these are markers on pathogens that allow the body to identify them. Each lymphocyte will produce a specific type of antibody: proteins that bind to antigens and damage/ destroy them. Some lymphocytes become dormant after an infection (they do not actively produce antibodies), and can be reactivated by infection by pathogens marked by antigens that they produce antibodies to. This allows the body to react quickly to any repeat infections i.e. become immune.