The adaptive immune system starts to work after the innate immune system is activated. If an infection progresses despite the inflammation, fever, natural killer (NK) cell and phagocyte activity of the innate immune system, a more coordinated response is required in order to destroy the pathogen. The adaptive immune response occurs a few days after the innate immune response is initiated. The major functions of the adaptive immune system include:
- The recognition of specific “non-self” antigens in the presence of “self” during the process of antigen presentation
- The generation of responses that are tailored to maximally eliminate specific pathogens or pathogen-infected cells
- The development of immunological memory in which each pathogen is “remembered” by a signature antibody, which can then be called upon to quickly eliminate a pathogen should subsequent infections occur.