NK cells

Question 1

What are they

Answer 1

a class of lymphocytes that recognize/kill infected/damaged cells

secrete IFN-gamma –> mac activation
granules –> directly killing

Question 2

activating NK cells

Answer 2

IL-15, IL-12, type 1 interferons

Question 3

Macrophage – NK cell relationship

Answer 3

Macrophage ingests microbe, secretes IL-12 —> NK cell stimulated releases IFN-gamma –> Mac activated to destroy microbes

Question 4

IgG and NK cells

Answer 4

NK cells have CD16, which recognize IgG and directly kill the cell

“ADCC” antibody dependent cytotoxicity

Question 5

activating receptors on NK cells use

Answer 5

ITEMS: cause downstream signaling —> IFN-gamma production/release

Question 6

NK inhibitory receptors

Answer 6

killer cell immunoglobin like receptors (KIRS)
contain immunoreceptor tyrosine based inhibitory motifs (ITEMS)

ITEMS phosphorylated on tyrosines when receptors bind to MHC I complexes

Question 7

KARs –>

Answer 7

activate Protein Tyrosine Kinase (PTK)

Question 8

KIRs —>

Answer 8

activate Protein Tyrosine Phosphatase (PTP) which inhibits PTK

Question 9

how do NK cells kill directly?

Answer 9

they recognize reduced expression of MHC 1 and directly kill the infected cell by release porforin and enzymes that degrade the cell

Question 10

how do NK cells kill indirectly?

Answer 10

they are activated by IL-12 from Macs; in turn, NK cells release IFN-gamma and activate the macs to induct them into the killing