title: An overview of the immune system.
abstract: We are continually exposed to organisms that are inhaled, swallowed, or inhabit our skin and mucous membranes. Whether these organisms penetrate and cause disease is a result of both the pathogenicity of the organism (the virulence factors at its disposal) and the integrity of host defence mechanisms. The immune system is an interactive network of lymphoid organs, cells, humoral factors, and cytokines. The essential function of the immune system in host defence is best illustrated when it goes wrong; underactivity resulting in the severe infections and tumours of immunodeficiency, overactivity in allergic and autoimmune disease. In this review we have covered the normal function of the immune system in recognising, repelling, and eradicating pathogens and other foreign molecules.
authors.affiliation: Department of Immunology, St Bartholomew's and the Royal London Hospital School of Medicine and Dentistry, Queen Mary and Westfield College, West Smithfield, EC1A 7BE, London, UK. Jackie.Parkin@bartsandthelondon.nhs.uk
authors.forename: J
authors.initials: J
authors.lastname: Parkin
authors.forename: B
authors.initials: B
authors.lastname: Cohen
mesh_terms: D001402:B-Lymphocytes / Q000502:physiology*; D016207:Cytokines / Q000502:physiology; D006801:Humans; D007107:Immune System / Q000502:physiology; D013601:T-Lymphocytes / Q000502:physiology*
chemical_list: D016207:Cytokines