[計(jì)算機(jī)]第3章補(bǔ)體系統(tǒng)(存儲(chǔ)版)
【正文】 molecular patterns are recognised by pattern recognition receptors (PRR) on host cells Examples of PAMPs are ? lipopolysaccharides (LPS or endotoxin) Gramnegative bacteria ? lipoteichoic acid Grampositive bacteria ? formylpeptides bacteria ? mannans yeast ? glycolipids mycobacteria ? doublestranded RNA, poly IC viruses M A I N F U N C T I O N S O F T H E C O M PL EM EN T SYST EM1. C 3 b O p s o n i s a t i o n / So l u b i l i z a t i o n o f i m m u n e c o m p l e x e s2 . C 3 a / C 5 a En h a n c e m e n t o f Ph a g o c y t o s i s D e g ra n u l a t i o n o f M a s t c e l l s i n c re a s e d v a s c u l a r p e rm e a b i l i t y3 . C 5 a C h e m o t a c t i c p e p t i d e a t t ra c t s Po l y m o rp h s4. C 8 / 9 L y s i sBenefits of C5a and C3b Most C3b binds to antigens on the microbial surface. Some C3b bines with C2a and C4b to form the third enzyme of the plement pathway that is able to split C5 into C5a and C5b. C5a stimulates mast cells to release histamine for inflammation and diapedesis. It also functions as a chemoattractant for phagocytes. The phagocytes are then able to bind to the C3b attached to the surface of the microanism allowing for opsonization (enhanced attachment). C 5 aP o l y m o r p h sr e s p i r a t o r y b u r s tC 3 b R e x p r e s s i o n M a s t C e l l s. . . . . .................d e g r a n u l a t i o n a n a p h y l a t o x i n s m e d i a t o r sc h e m o t a c t i c p e p t i d e i n c r e a s e s v a s c u l a r p e r m e a b i l i t yC 3 b B bm i c r o b eC 3 bt i s s u e i n v a s i o no p s o n i s a t i o nC 3 aplement recognition molecules and receptors ? CR1 (CD35) mono/macs, PMN, lymphocytes, RBC C3b/4b phagocytosis ? CR2 (CD21) Bcells, FDC iC3b, C3d augments B cell activation ? CR3 (CD11b/18) mono/macs, PMN, NK iC3b, LPS adhesion, clearance ? CRP Ca++ dependent C1q binding, activates classical p, phagocytosis, apoptosis plement : structure and function Initiating pathways: ? classical pathway ? mannanbinding lectin pathway ? alternative pathway Effector pathway ? C3a, C4a, C5a inflammatory cell chemotaxis, mastcell degran ? C3b opsonin via C3bR, solubilisation of ic ? C5bC8, C9 membrane attack plex cell lysis Regulatory proteins ? control the amplification cascade ? short enzyme half life, Regulatory proteins C 3 bBbD A FC R 1 / M C PB r e a k d o w n o f C 3 c o n v e r ta s ePI GN O R M A LM e m b r a n e B o u n d R e g u l a to r sD e c a y A c c e l e r a ti n g F a c to rC o m p l e m e n t R e c e p to r IM e m b r a n e C o F a c to r Pr o te i nC 1 qC 1 r C 1 sC 4 aC 4 bC 4 aC 4 bM i c ro b eI o n
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