February 26, 2008
MBL= mannose-binding lectin
= opsonin
Mannose receptor
• Also interacts with mannose on microbe surface
• NOT an opsonin
• Is a protein on macrophage surface
Phagocytosis of NON-OPSONIZED
Microbe:
1. Mannose receptor binds mannose on microbe surface
Example of a receptor that binds both an opsonin and directly to microbe= CR3-> binds antibody conserved region, also binds β-glucan in bacteria cell wall
b. Actin polymerization triggered by Rho-family GTPases
c. Vacuole with microbe fuses with primary granules
*Concentration of antimicrobial peptides in phagocytosis >1µM
*Lysozyme, bacterial permeability increasing protein (BPI)
*Proteases (both are in primary granules)
ii. Secondary granules
• NADPH oxidase
Creates reactive oxygen species
*Creates free radical which damage DNA and proteins
• Microbial resistance
*S.aureus makes catalase, which destroys ROSs.
ii.
2. Reactive Nitrogen Species
a. iNOS (inducible nitric oxide synthase)
b. Transcription and translation of iNOS turned on in response to phagocytosis
c. iNOS transcription activated by LPS, other bacterial products IFN γ (interferon-gamma) and other cytokines
