title: Host defense mechanisms against pathogens.
abstract: OBJECTIVE
  The body is under constant assault by potentially harmful microbes. Both innate and adaptive immune responses counteract the action of pathogens.
  
  
  METHODS
  Review of the pertinent literature.
  
  
  RESULTS
  The innate response is focused mainly on physically eliminating the pathogens, mostly by phagocytosis, while the adaptive response reacts specifically to, and neutralizes, a given pathogen and maintains a memory of it for safer and faster elimination on subsequent encounters.
  
  
  CONCLUSIONS
  The basic mechanisms of pathogen elimination by the immune system and some mechanisms of evasion of the immune response by pathogens are discussed.
authors.affiliation: General Pathology and Immunology, Department of Clinical and Biological Sciences, School of Medicine, University of Insubria, Varese, Italy. roberto.accolla@uninsubria.it
authors.forename: Roberto S
authors.initials: RS
authors.lastname: Accolla
mesh_terms: D001424:Bacterial Infections / Q000276:immunology*; D003713:Dendritic Cells / Q000276:immunology; D007110:Immunity, Active; D007113:Immunity, Innate; D008264:Macrophages / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology