title: Innate immunity and its role against infections.
abstract: OBJECTIVE
  This article reviews current concepts of the innate immune system that offers protection against infections. It offers an overview for the readers to understand how innate immunity, consisting of different receptors, cells, and mediators recognizes pathogens and exerts protective function against pathogens.
  
  
  METHODS
  MEDLINE-search articles including original research papers, review articles, textbooks, and references identified from bibliographies of relevant articles.
  
  
  CONCLUSIONS
  The innate immune system is nonspecific immunity present since birth not requiring repeated exposure to pathogens. It is capable of differentiation between self and nonself. Because of its nonspecificity, it has a broad spectrum of resistance to infection. Further, it is thought to play an important role in the control of adaptive immunity by regulating co-stimulatory molecules and effector cytokines. Innate immunity includes pattern recognition molecules/receptors, antimicrobial peptides, the complement system, inflammatory mediators, and cytokines produced by immune cells. Pattern recognition molecules/receptors recognize pathogen-associated molecular patterns that are essential for microorganisms' survival and pathogenicity. Although innate immunity has recently gained increasing importance, further studies are necessary for a better understanding of its role.
authors.affiliation: Department of Pediatrics, University of South Florida College of Medicine, All Children's Hospital, St. Petersburg 33701, USA.
authors.forename: Suwannee
authors.initials: S
authors.lastname: Uthaisangsook
authors.forename: Noorbibi K
authors.initials: NK
authors.lastname: Day
authors.forename: Sami L
authors.initials: SL
authors.lastname: Bahna
authors.forename: Robert A
authors.initials: RA
authors.lastname: Good
authors.forename: Soichi
authors.initials: S
authors.lastname: Haraguchi
mesh_terms: D000818:Animals; D003094:Collagen / Q000276:immunology; D029721:Drosophila Proteins; D006801:Humans; D007113:Immunity, Innate; D007239:Infections / Q000276:immunology*; D018836:Inflammation Mediators / Q000502:physiology; D018950:Lipopolysaccharide Receptors / Q000502:physiology; D008214:Lymphocytes / Q000276:immunology; D008407:Mast Cells / Q000502:physiology; D008562:Membrane Glycoproteins / Q000502:physiology; D009838:Oligodeoxyribonucleotides / Q000494:pharmacology; D010586:Phagocytes / Q000502:physiology; D011956:Receptors, Cell Surface / Q000502:physiology; D051193:Toll-Like Receptors
chemical_list: C408982:CPG-oligonucleotide; D029721:Drosophila Proteins; D018836:Inflammation Mediators; D018950:Lipopolysaccharide Receptors; D008562:Membrane Glycoproteins; D009838:Oligodeoxyribonucleotides; D011956:Receptors, Cell Surface; D051193:Toll-Like Receptors; D003094:Collagen