The immune system is our ‘always on’ defense system, continuously carrying out surveillance to protect us from infections. Upon exposure to a pathogen, the immune system defends the body from harm via a two-pronged approach: innate immunity and adaptive (or acquired) immunity.
As Dr. Bruins explains, innate immunity is the immunity that humans are born with, consisting of physical barriers that protect the body from pathogen invasion and first line of cellular defenses that recognize and remove immediate infectious threats. Throughout life, we also acquire a second line of defense, the adaptive immune system. The adaptive, or acquired, immune response is slower than the innate response (days to weeks); however, adaptive immunity is more specific towards eliminating pathogens and has memory. The adaptive immunity comprises specialized white blood cells – namely T and B lymphocytes. These work together to identify and destroy infected host cells through the production of antibodies that travel through the bloodstream and bind to the invader, flagging the invader for destruction by immune cells. Vitally, the adaptive immune system that learns from new acquired infections, generates ‘memory cells’, which enables a fast-adaptive response if the body is re-infected by the same pathogen.
