title: Immune system: introduction.
mesh_terms: D000328:Adult; D000818:Animals; D000941:Antigens; D006801:Humans; D007109:Immunity; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D008221:Lymphoid Tissue / Q000276:immunology; D051379:Mice; D009369:Neoplasms / Q000276:immunology; D013950:Thymus Gland / Q000276:immunology
chemical_list: D000941:Antigens; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M