Lecture 22 - Innate Immunology Flashcards
How do phagocytes recognize and engulf external pathogens?
It uses the toll-like receptor present on the membranes.
How do phagocytes recognize internal pathogens?
It uses NOD-like receptor and/or RIG1-like receptor in the cytoplasm.
What happens during phagocytosis?
- Phagocyte engulfs bacteria, vesicle is the phagosome
- Phagosome fuses with lysosome, making it a phagolysosome
- Release digestive enzyme and a oxidative burst
What are four ways in which the pathogens can resist being destroyed?
- antioxidants to fight oxidative burst
- oxidants to kill phagocyte
- toxins called leukocidins to kill PMNs and monocytes
- prevent phagocytosis with capsules
What is granoluma?
a sac like structure formed by the fusion of phagocytes (macrophages, giant cells, and T cells)
What disease is well known for granuloma formation?
in tuberculosis, bacteria break out the granulomas
What are the antigen presenting cells?
B cells (lymphocyte)
Macrophages (phagocyte)
Dendritic cell (phagocyte)
What is MHCI?
Major histocompatibility complex I - Mounts antigen from cytoplasm. Found on all nucleated cells
What is MHC2?
Major histocompatibility complex II - Mounts antigens from phagolysosome. Found only on APCs
Why do MHC protein have to matched for tissue allografts?
allografts are form other sources, so if their MHC proteins are different, the body will try to eliminate it
MHC1 presents both ____ and_________ equally
self and non-self
What is the difference between recruiting Tc cells and Th cells?
Tc cells are recruited by MHCI to kill the infected cell
Th cells are recruited by MHCII to activate the adaptive immune response
What are interferons?
induced by viral infected cells when RLR binds to viral nucleic acid.
interferon diffuses to neighboring cells and induces synthesis of antiviral proteins
What are three outcomes of the complement system?
- Release cytokines to induce inflammation
- Build the membrane attack complex and insert it in a foreign cell
- opsonize foreign cell
What are the different way to activate the complement system?
- Classical pathway
- Alternate (properdin) pathway
- Mannan-binding lectin pathway
How does the classical pathway work?
- Antibodies/immunoglobulins bind to bacterial surface antigens
- Uses many complement proteins, start with C1
- C3a induces vascular permeability
- C2a, C3b, C4b make convertase
- C5a attracts phagocytes
- C5b recruits rest of membrane attack complex
How does the alternate (properdin) pathway work?
- Uses many complement proteins, start with C3
- When C3b binds bacteria it brings in Factor B
- C3b dimer, Bb, and properdin make convertase
- C3a, C5a induce inflammation and recruit macrophages
- C5b recruits rest of MAC
How does the Mannan-binding lectin (MBL) pathway work?
- MBL binds mannose and N-acetyl-glucosamine on bacterial cell
- C2a, C3b, C4b make convertase
- C3a, C5a induce inflammation and recruit macrophages
- C5b recruits rest of MAC
