Dendritic cells and migration, host innate immune receptors

Question 1

What do macrophages do?

Answer 1

Receptors of macrophages recognize specific structures on the microbe
Macrophages engulf and digest bacteria to which they bind via specific receptors

Question 2

Name 3 types of innate receptors

Answer 2

Innate receptors
Family of receptors that recognize different structures
- C-type lectins (CLR) > glycan structures
- Toll-like receptors (TLR) > important in activation
- FC-receptors (FcR) > recognize antibodies covered on the microbe
- Complement receptor (CR) > recognize complement fixed microbes

Question 3

What do C-type lectin receptors (CLR) recognize?

Answer 3

glycan structures

Ctype lectin receptors are mostly on the cell surface of DCs and macrophages
They have all lectin domains > can recognize carbohydrate structures on pathogens > when they bind the carbohydrate with the antigen attached they internalize and the antigen is degraded

Question 4

What do Toll-like receptors (TLR) recognize?

Answer 4

LPS
Flagellin
dsRNA / ssRNA
CpG (viral component)

Very specific
Pathogen-associated molecular patterns (PAMPs)

Question 5

What do FC receptors (RcR) recognize?

Answer 5

antibodies covered on the microbe

Immune complexes consisting of IgG and antigens
Induce internalization of the immune complexes
Signaling cascade

Carbohydrate binding proteins

Question 6

What do Complement receptors (CR) recognize?

Answer 6

Complement fixed microbes

Question 7

Dendritic cells respond by which type of receptor?

Answer 7

C-type lectin receptors

Dendritic cells respond by Ctype lectin receptors > purple receptor, internalizes to the lysosome and present it to the MHC1 and it can be presented to Tcells

Question 8

What happens after Toll-like receptors recognize a pathogen?

Answer 8

Toll like receptors recognize pathogen specific patterns or danger associated patterns > strong signaling receptors > communicate to the nucleus which produces NFkappaB > cytokines are stimulated and co-stimulatory and adhesion molecules
Important for presenting antigen presenting factor

Question 9

Steps in adaptive immune response

Answer 9

1 = bacteria enters
2 = APC take up and process
3 = APC migrate to the draining lymph node and presents to Tcells
4 = APC Ag presentation
5 = activation CD4 naïve Tcells or Bcells

Question 10

Which receptor can have an ITIM motif?

Answer 10

Cytoplasmic tail of Fc receptors

certain are activating > stimulate responses and degradation but can also have an inhibitory motif > it signals in a negatively way and inhibits immune responses for example with the ITIM motif

Question 11

What does TLR4 recognizes?

Answer 11

LPS

Question 12

What does TLR5 recognizes?

Answer 12

Flagellin

Question 13

What does TLR7 recognizes?

Answer 13

ssRNA

Question 14

What does TLR9 recognizes?

Answer 14

CpG

Question 15

What does TLR3 recognizes?

Answer 15

dsRNA

Question 16

What does NFkappaB do?

Answer 16

Gets activated by TLR which is in the cell nucleus

Stimulate production of inflammatory cytokines and/or chemokines

Question 17

What does TLR1, TLR2 and TLR6 recognize?

Answer 17

lipopeptides

Question 18

What are type 1 interferons?

Answer 18

Viruses, when they infect the host, start producing interferons > will help to stimulate the immune response to get rid of the viral response