The role of the immune system is to protect the body from pathogens, toxins, and potential threats. The individual components of the immune system are spread throughout the body but work together to coordinate an effective immune response and to keep us safe.
An immune response is triggered as soon as a foreign particle enters the body. The purpose of the innate, or non-specific, immune system is to prevent the movement and spread of foreign particles throughout the body. Through the help of natural killer cells, macrophages, neutrophils, and dendritic cells among others, it acts quickly to provide the first line of defence against potential threats. This part of the immune system is considered ‘innate’ because it is present in the body from birth.
In contrast, the adaptive immune system (also known as the acquired or specific immune system) develops over time in response to exposure to antigens. The adaptive immune system relies on T and B lymphocytes to remember foreign invaders and recognise them when they enter the body again. Developing immunological memory against specific antigens therefore helps to optimise the immune response.
Vaccines rely on the adaptive immune system in order to develop immunity against a certain infection. When a person is vaccinated, they are injected with a less severe form of an infection so as to encourage their immune system to create “memory” T-lymphocytes and B-lymphocytes that will remember how to fight that disease in the future. Whereas the innate immune system is non-specific, acting quickly on a range of pathogens, adaptive immunity is highly specific and requires a few weeks for the immune system to build up immunity to a certain disease.