innate imunity

• dendritic cell

  antigen presenting to T cells
• natural killer cell

  controls viral infection by killing tumour and virus infected cells
• neutrophil


  mediate early inflammation
• eosinophils

  parasite killing and contribute to asthma
• mast cells

  release histamines that activates endothelium and increases blood vessel permeability
• monocytes

  short lived source of resident macrophages and dendritic cells
• macrophage

  phagocytosis, angiogenesis, synthesis of collagen rich ECM, and wound healing
• angiogenesis

  new blood vessel growth
• NK cells give immunity to viruses and cancer, and cause chronic inflammation
• ILC1 offers immunity to intracellular bacteria and protazoa, and cause chronic inflammation
• ILC2 offer immunity to helminths
• ILC give immunity to extracellular bacteria and cause chronic inflammation
• defensins

  form pores
• lactoferrin

  binds and transports iron, which is anti bacterial and anti fungal
• complement system is activated by recognition of pathogens
• complement system results in enhancement of phagocytosis via opsonisation, inflammation, and lysis of microbes
• C3b binds to microbe for phagocytosis
• c3a binds to mast cells to release histamines
• alternative pathway

  c3b binds to activating surfaces such as cell walls
• classical pathway

  c1 binding to antigen-antibody complexes
• lectin pathway

  binding of lectins in plasma to carbohydrates on microbes
• c3a

  inflammation
• c3b

  opsonisation and phagocytosis
• c5a

  inflammation
• c6-9

  lysis of microbe
• c3b binds to antibody and becomes component of the enzyme that cleaves c5 and initiates the late steps of complement activation
• c5b initiates late steps of complement activation, producing c5a
• c5b forms a complex with c6-9 to form MAC
• MAC

  makes pores in membrane to allow water and ion movement, resulting in lysis of microbe
• macrophages dont circulate, trap antigen at site of infection, are derived from monocytes, and can produce cytokines
• inflammatory macrophages live for days to weeks
• tissue resident macrophages live for years
• neutrophils increase during acute inflammation, and secrete lysosomal enzymes, first cells to migrate during inflammation
• pus is mostly dead neutrophils
• neutrophils are short lived, 1-2 days
• phagocytosis steps

  chemotaxis, adherence, ingestion, digestion, killing
• chemotaxis

  movement of phagocytes to site of damage due to chemical stimulus
• adherence

  attachment of phagocyte to microbe
• oxidative bursts generate oxygen radicals, and nitric oxide
• opsonisation

  microbes targeted for destruction for phagocytes