08hostdefenseagainstinfect宿主防御(编辑修改稿)

08hostdefenseagainstinfect宿主防御(编辑修改稿)内容摘要：

Antimicrobial Peptides/Defensins  Four hundred peptides described to date  Defensins (3 5kD, four families in eukaryotes)  adefensins (neutrophils and intestinal Pah cells)  bdefensins (epithelial cells)  Insect defensins  Plant defensins  Defensins appear to act by binding to outer membrane of bacteria, resulting in increased membrane permeability.  May also play a role in inflammation and wound repair Complement System  Three pathways now known  Classical  Alternative  Lectin or MBL pathway (binding to mannosecontaining carbohydrates)  Host cells have plement regulatory proteins on their surface that protect them from spontaneous activation of C3 molecules Inflammatory Mediators in Innate Immunity  Cytokines secreted by phagocytes in response to infection include:  IL1  activates vascular endothelium and lymphocytes  Increases adhesiveness of leukocytes  IL6  Induces Bcell terminal maturation into Igproducing plasma cells  IL8  Induces expression of b2 integrin adhesion molecules on neutrophils, leading to neutrophil migration to infection site  IL12  Activates NK cells and induces Th1cell differentiation  IL18  TNFa  Activates vascular endothelium and increases vascular permeability, leading to accumulation of Ig and plement in infected tissues Other Mediators and Molecules  Phagocytes  Toxic oxygen radicals  Peroxides  Nitric oxide (NO)  Lipid mediators of inflammation  Prostaglandins  LTB4  Platelet activating factor  Complement ponent C5a  Stimulates mast cells to release histamine, serotonin and LTB4  IL1, IL6 and TNFa  Induce acutephase response in liver  Induce fever  IL1 and IL18 signaling pathway。