Immune function is a complex balancing act between just enough and not too much. We are born with two powerful branches of immunity: the innate and the adaptive immune system, and the normal function of both is essential for health. The innate immune system is our first line of defense and includes cells like macrophages, neutrophils, mast cells, and natural killer (NK) cells. These cells have special receptors that recognize pathogens in our environment, responding to them swiftly and efficiently, inside or outside of cells.
When a pathogen cannot be dealt with by the innate immune system alone, it calls on the adaptive immune system for help. This system, composed of T cells and B cell, is what allows our bodies to mount antibody responses (with B cells), to directly kill cells growing out of control or infected by viruses (with cytotoxic T and NK cell), and to coordinate the right type of response, at the right time, to restore normal function. These responses are all communicated by special chemical messengers, called cytokines, that allow our immune system to talk to itself throughout the body. We need just enough communication to get the job done, but not so much that things get out of hand.