Innate Immune System Flashcards
Complement enzyme
C3 convertase
Complement components for inflammatory response
C3a
C4a
C5a
Complement components for opsonization
C3b
C4b
Complement components for MAC complex
C5b-C9
Antimicrobial substance secreted by skin; lytic to microbes
Defensin
What types of cells secrete cytokines?
Keratinocytes
Dendritic cells
Mast cells
Endothelial cells
PRR that recognizes gram-negative bacterial LPS, fungal mannans, and viral envelope proteins
TRL-4
Transcription factor activated by PAMPs via PRRs
NFkB
Alternative complement pathway activation
Binding of C3 to a PAMP
Classical complement pathway activation
Antibody (IgM or IgG) binds to an antigen
Lectin complement pathway activation
Mannose-binding lectin (soluble PRR) in serum binds to mannose residues on microbes (type of PAMP)
C5a function
Chemokine to recruit neutrophils
C3a and C5a function
Mast cell degradation –> release of histamine
C5b function
Binds membrane of microbe; induces formation of the rest of MAC
Mechanism of action of Type I IFN
- Viral RNA is recognized by cytoplasmic PRRs
- Transcription of IFN alpha and beta
- Signals to nearby cells to stimulate activation of transcription of antiviral genes (antiviral proteins that inhibit TRANSLATION)
Macrophage function
Phagocytosis
Secrete cytokines that attract immune cells
Neutrophil function
Phagocytosis; inflammation
Eosinophil function
Parasitic infection
Mast cell function
Allergic reaction; release histamine
Mediate vasodilation and vascular permeability
Basophil function
Allergic reaction; release histamine
NK cell function
Cell cytotoxicity
What binds to induce opsonization?
- Fc receptor on phagocyte binds to IgG
2. CR1 receptor binds to C3b
How do NK cells bind to other cells?
NK cells have two receptors: killer activating and killer inhibiting
Normal cells will bind to both NK receptors–a common molecule binds to Killer activating and MHC I binds to Killer inhibiting
Abnormal cells lack MHC, therefore they only bind to killer-activating receptor
What changes in vascular flow occur during acute inflammatory response?
- Vasodilation
2. Vascular permeability: “leaky” blood vessels allows for extravasation of neutrophils and other inflammatory cells
What are the professional APCs?
Macrophages
Dendritic cells
How does the innate system interact with the adaptive system?
Via macrophages and dendritic cells, which are professional APCs
What is the result of TLR-4 stimulation of macrophages?
Transcription of genes for cytokines, adhesion molecules and co-stimulatory molecules
