Lecture 4 - 8/29/19

Question 1

why does alternative pathway activate first

Answer 1

because the C3 can bind any hydroxyl group and any amino group on a protein or other things

Question 2

what type of system can classic pathway work in

Answer 2

both innate and adaptive

Question 3

what are defensins

Answer 3

penetrate pathogen membrance causing its disruption. they’re secreted at mucosal surfaces. also produced by neutrophils and stored in the granules. alpha is produced by intestinal epithelial cells. beta is produced by epithelial cells in a broad range of tissues

Question 4

what are pentraxins

Answer 4

short ones are synthesized by liver. long ones by a variety of cells. circulate in blood and lymph and target pathogens to be destroyed. Act as a bridge between pathogen and phagocyte (similar to Ab)

Question 5

describe immediate innate response

Answer 5

0-4 hours pathogen invades tissue and proliferates. pathogen is recognied by preformed soluble effector molecules and resident effector cells in the infected tissue. pathogen is either eliminated and infection ends or pathogen is not eliminated; proceed with the induced innate immune response.

Question 6

describe induced innate immune response

Answer 6

4 hours to 4 days. pathogen invades tissue and proliferates. activation of cells resident in the infected tissue. recruitment of effector cells to the infected tissue. inflammation, fever, the acute-phase response. soluble effector molecules and UNF

Question 7

what are cytokines

Answer 7

they’re proteins that mediate the effector functions of the immune system. they act on specific receptors expressed on other leukocytes. most are soluble proteins; released by one cell, bind to receptors of another cell, induce biological effects. very few but some are membrane-bound (TNF family) they regulate intensity, form and duration of immune response

Question 8

are cytokines ag-specific

Answer 8

no they’re not. only those lymphocytes responding to a specific immunogen are affected by cytokines; these lymphocytes express the correct cytokines receptors. direct cell-to-cell interactions between cells responding to the same Ag.

Question 9

what factors do cytokines effects depend on

Answer 9

the target cell, the state of differentiation of the target cell, the presence or absence of other cytokines

Question 10

name 3 cytokines effects

Answer 10

endocrine action - released into the bloodstream to bind distant cells. paracrine action - released to bind nearby cells. autocrine action - released, bu then bind to receptors on the cell that produced them

Question 11

describe receptors on innate immune cells

Answer 11

each R recognizes multiple pathogenic species so a few number of receptors are needed. there are about 100 different R and each cell type expresses only a subset of them

Question 12

list some phagocytic and signaling receptors on macrophages

Answer 12

mannose receptor, complement receptors 3 and 4, dectin-1, macrophage receptor with collagenous structure (MARCO) scavenger receptor A (SR-A) scavernger receptor B (SR-B) UNF

Question 13

describe TLR4

Answer 13

toll-like receptor on MQ recognizes LPS on bacteria and induces change in gene expressions. activation of TLR4 leads to the activates of the transcription factor NFkB.

Question 14

what all can member of TLR recognize

Answer 14

virus, fungi and parasites. extracellular: cell plasma Mb receptors recognize ligands on he stuface of pathogen. intracellular on endosomes recognize nucleic acid from pathogens

Question 15

describe IL-1beta and TNF-alpha cyotokines

Answer 15

induce blood vessels to become more permeable, enabling effector cells and fluid containing soluble effecotr molecules to enter the infected tissue.

Question 16

describe IL-6 cytokine

Answer 16

induces fat and muscle cells to metabolize, make heat and raise the temperature in the infected tissue. increases production of acute-phase proteins by the liver

Question 17

describe CXCL8

Answer 17

recruits neutrophils from the blood and guides them to the infected tissue (chemoattractant)

Question 18

describe IL-12 cytokine

Answer 18

recruits and activates natural killer (NK) cells that in turn secrete cytokines that strengthen the macrophages’ response to the infection

Question 19

where do the previously described cytokine come from

Answer 19

resident macrophages secrete the cytokines

Question 20

describe interferons (IFN) family of cytokines

Answer 20

the most important kind of cytokine during viral infections. type I interferon genes are transcribed as a result of sensing double-stranded RNA

Question 21

describe proudction of IFN by virus-infected cell

Answer 21

IFN makes infected cell more susceptible to be attacked. binds to NK cells to activate them and are drawn to site of infection.

Question 22

describe NK cells

Answer 22

responders during innate immunity, form synapses with infected cells and with MQ, activated by IFN type I

Question 23

what are the functions of NK cells

Answer 23

non-phagocytic but cytotoxic: kill tumor and/or virus-infected cells. form NK-cell synapse, produce cytokines (increase state of inflammation, production of cytokines by MQ, increase MQ phagocytic activity, so an overall increase in inflamation)

Question 24

what is special about NK cells

Answer 24

only cells that express TLR 3 and TLR8, both intracellular. main source of IFNy during innate response