What makes up the immune system?

♦  In general, there are two parts to the human immune system: innate (or broad-spectrum) and adaptive.

♦  Innate immune cells are found both in circulating blood and in tissues and are the first to engage pathogens, normally within several hours or up to several days after infection when the pathogen load is low

♦  Innate immune cells lack the ability to specifically identify pathogens, they just know that it is not one of ours and must be destroyed; dead pathogens are ultimately transported to the thymus gland where innate and adaptive immunity meet.

♦  After obtaining the specific pathogen information from innate immune cells in the thymus gland, adaptive immune cells are subjected to rigorous training in order to quickly learn how to recognize and kill the pathogen and not confuse it with our own cells; upon successful training, new adaptive immune cells are mass produced, called ‘clonal expansion,’ normally taking around 4-7 days after infection.