The immune system, including its inflammatory components, is fundamental to host defence
against pathogenic invaders. It is a complex system involving interactions amongst many
different cell types dispersed throughout the body. Central to its actions are phagocytosis of
bacteria, processing of antigens derived from intracellular and extracellular pathogens,
activation of T cells with clonal expansion (proliferation) and production of cytokines that
elicit effector cell functions such as antibody production and killing cell activity. Inappropriate …