immune receptor-ligand interactions

Question 1

how does cell communication occur?

Answer 1

via cytokines and receptors, soluble factors, surface molecules, and antigen presentation

Question 2

what are PAMPs?

Answer 2

pathogen-associated molecular patterns, i.e., a piece/fragment of a bacterial pathogen (ex. LPS on Gram-negative bacteria). They are recognized by pattern recognition receptors (PRRs) or sensors. PAMPS binding to PRRs initiates an immune response

Question 3

what are Toll-like receptors?

Answer 3

TLRs are a type of PRR that are located on the cellular membranes of leukocytes involved in innate immunity mechanisms. They are trans-membrane signal receptor proteins

Question 4

how many different TLRs do humans have?

Answer 4

10 (lack TLR11, TLR12, TLR13)

Question 5

what is the function of extracellular TLRs?

Answer 5

to detect molecules found outside of the cells

Question 6

where are intracellular TLRs found?

Answer 6

in the wall of endosomes, located inside the cell

Question 7

what is the effect of TLR activation?

Answer 7

cell signalling activation/repression, gene expression, production of inflammatory mediators including cytokines, chemokines, etc.

Question 8

what is the definition of a cytokine?

Answer 8

a low-molecular weight protein that regulates cell function and shapes the immune response

Question 9

what do sensor cells do?

Answer 9

constantly monitor host tissues for any foreign body/pathogen, i.e., constantly looking out for any stress or danger in the host.
When they sense something wrong, they activate the production of cytokines

Question 10

autocrine

Answer 10

the cell producing the cytokine is its own target cell

Question 11

paracrine

Answer 11

the target cell is in close proximity to the cell secreting the cytokine

Question 12

endocrine

Answer 12

the cytokine needs to travel through the bloodstream to reach the target cell

Question 13

what is pleiotropy?

Answer 13

different biological effects that are induced depending on the nature of the target cell

Question 14

what is redundancy in regards to cytokine attributes?

Answer 14

two or more cytokines mediate similar functions

Question 15

what is synergy?

Answer 15

combined effect of two or more cytokines on cellular activity is greater than the additive affects of the individual cytokines. induces a class switch to IgE

Question 16

what is antagonism?

Answer 16

effect of one cytokine inhibits the effect of another

Question 17

what is cascade induction?

Answer 17

action of one cytokine on a target cell causing that cell to produce one or more additional cytokines

Question 18

how does the immunity system avoid an infinite feedback loop where there is uncontrolled inflammation?

Answer 18

production of anti-inflammatories such as IL-10, non-immunity related hormones, and soluble or membrane-bound TNFs

Question 19

what is the role of chemokines?

Answer 19

provide signals to immune cells to help them traffic to site of inflammation, homing to organs/tissues

Question 20

what are the cytokine receptor types?

Answer 20

1. interleukin-1
2. class 1 cytokine receptors
3. class II cytokine receptor family
4. TNF receptor family
5. chemokine receptor

Question 21

what are Il-1 receptors?

Answer 21

monomeric and inhibitor ligands with only the heterodimeric receptor able to transduce a signal. Il-1 receptors change in ratio of functional and inhibitor receptors to modulate the immune response

Question 22

Class I cytokine receptors

Answer 22

receptor that most cytokines bind to, and are made up of at least two subunits: alpha and beta subunits. these subunits explain the redundancy and antagonism of some cytokines

Question 23

class II cytokine receptor

Answer 23

also known as the IFN (interfeuron) family. Made up of three types of IFNs and are characterized as heterodimers. the family consists of 12 different receptor chains that in their various assortments, bind to at least 27 class II cytokines

Question 24

TNF receptor family

Answer 24

cytokines that are trimers and can either be membrane-bound or soluble. these receptors can also act as decoys, preventing cytokines from binding to membrane-bound receptors.

Question 25

Il-17 receptor family

Answer 25

mostly proinflammatory, IL-17 cytokines are secreted as dimers, and receptors are either dimeric or trimeric, and can be homo or hetero dimers/trimers

Question 26

what is the role of chemokines? what are characteristics of chemokines

Answer 26

influence cell movement, i.e., chemotaxis. chemokines have a tertiary structure which is determined by the presence of highly-conserved disulfide bonds; the position of these bonds determine classification

Question 27

what receptors do chemokines act on?

Answer 27

G protein coupled-receptors

Question 28

what happens in consequence to cell signaling upon ligand binding?

Answer 28

production of cytokines, receptor expression, cell polarization, change in cell metabolism

Question 29

what is mediator of the negative feedback loop to ligand binding?

Answer 29

SOC3, prevents tyrosine phosphorylation of STAT

Question 30

what are the varying levels of cytokine receptors based on?

Answer 30

strength of signal binding and transduction, based off number of subunits within one receptor

Question 31

what do varying levels of cytokines influence during hematopoeisis?

Answer 31

proliferation and differentiation, as well as cell polarization and functions