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Flashcards in Dial Deck (7)
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1
Q

What are NK cell-activating cytokines?

A

IL-15: maturation of NK cells
Type I IFNs: enhance killing functions of NK cells
IL-12: enhance killing functions of NK cells

2
Q

What receptors activate NK cells?

A

NKG2D: recognizes molecules that resemble MHC I proteins
CD16: specific for IgG bound to cells
ITAMs (immunoreceptor tyrosine-based activating motifs): in cytoplasmic tails which phosphorylates on tyrosine residues leading to cytotoxic granule exocytosis and production of IFN-y

3
Q

What are the inhibitory receptors of NK cells?

A

Killer cells immunoglobulin-like receptors (KIRs)
CD94 and lectin subunit NKG2
ITIMS- phosphorylated ITIMs bind and promote activation of cytoplasmic protein tyrosine phosphatases, which remove phosphate groups from tyrosine resides; counteracting activating ITAMs

4
Q

How do CD8+ CTL recognize class MHC 1 molecules?

A

They recognize the MHC I complexes on the surface of infected cells via the TCR and the CD8 coreceptor

5
Q

How do CD8+ CTL hold on to infected cells?

A

LFA-1 integrin binds and holds the cell forming the immunologic synapse

6
Q

How do CD8+ CTL kill infected cells?

A

When an antigen in recognized a pathway is activated to release granules into the synapse. Perforin is released to make pores in the infected cell for Granzyme B to enter and cleave/activate caspase to induce apoptosis. Also expresses Fas ligand to bind apoptosis inducing Fas in infected cells

7
Q

What strategies do viral pathogens use to evade cell-mediated immune defenses?

A

Mycobacteria- inhibit phagolysosomes fusion
Herpes- inhibits antigen presentation by interfering with TAP transporter
Cytomegalovirus- inhibits antigen presentation and proteosomal activity and remove MHC I molecules from ER
Epstein- Barr virus: inhibits antigen presentation macrophage and dendritic cell activation and proteosomal activity
produces IL-10
Pox Virus- inhibition of effector cell activation and produces soluble cytokine receptors