Question 1

Toll-like receptors and other receptors are potent activators of various components of the innate immune system.All of the following proteins are expressed in response to signaling by these receptors EXCEPT:

Accepted Answer

CD28,the activating receptor for B7-1 and B7-2 costimulatory molecules,is constitutively expressed on the surface of many T cells and is not induced by Toll-like receptor (TLR)signaling.TLR signaling does induce expression of B7-1 and B7-2 on antigen-presenting cells.Other genes expressed in response to TLR signaling encode proteins important in many different components of innate immune responses.These include inflammatory cytokines such as tumor necrosis factor-F1F1F1S1F1F1F10 (TNF-F1F1F1S1F1F1F10),interleukin-1 (IL-1),and IL-12;endothelial adhesion molecules such as E-selectin;and proteins involved in microbial killing mechanisms,including inducible nitric oxide synthase (iNOS).The specific genes expressed depend on the cell type of the responding cell.
Matching

Question 2

Cytosolic DNA sensors are a large group of molecules that detect microbial dsDNA in the cytosol of infected cells,and situate innate responses.Most of these sensors signal though a pathway that includes which protein?

Accepted Answer

STING is present in the endoplasmic reticulum (ER)membrane of most cells,and functions as an adaptor protein that binds cytosolic dsDNA sensors.STING then interacts with other molecules to generate signals,which activate IRF transcription factors and type interferon gene expression.MAVS are involved in signaling initiated by RLR binding to cytosolic ssRNA.TLR9 is an endosome membrane DNA sensor.Cytochrome C is a mitochondrial protein involved in cellular energy metabolism,but stimulates apoptosis when released into the cytosol.

Question 3

Toll-like receptors (TLRs)are a family of homologous receptors expressed on many cell types and are involved in innate immune responses.Some TLRs are expressed on the plasma membrane,Others are expressed on endosomal membranes indie the cells.Which of the following is a shared property of the TLRs in the endosomes?

Accepted Answer

More than 10 mammalian Toll-like receptors (TLRs)have been identified,and each recognizes a different set of structures.TLRs located in endosomes (TLRs 3,7,and 9)recognize forms of nucleic acids.TLR3 recognized double-stranded RNA produced by viruses.TLR9 binds ssRNA.TLR9 binds unmethylated cytosine guanosine (CpG)motifs typical of bacterial and protozoan DNA.Cell surface TLRs,TLR2 and TLR 4 recognize the components bacterial cell walls lipoteichoic acid and lipopolysaccharide,respectively.Endosomal TLRs signal via TRIF-IRF pathways,not JAK-STAT pathways,which promote inflammatory and anti-viral responses.Cells do not secrete TLRs.

Question 4

For each of the descriptions of a component of the innate immune system in questions ,select the term that best matches it from the list below (A-J).
-Produced by B-1 cells,protects against microbes that succeed in penetrating epithelial barriers

Accepted Answer

Natural antibodies are IgM antibodies produced by B1 B cells.They have very limited diversity and bind to commonly encountered microbial structures,such as phosphoryl choline.

Question 5

For each of the descriptions of a component of the innate immune system in questions ,select the term that best matches it from the list below (A-J).
-Superoxide anion,hydroxyl radical,or hydrogen peroxide,produced by activated phagocytes

Accepted Answer

Reactive oxygen intermediates (ROIs)are generated by enzymes in phagocytes,such as phagocyte oxidase and myeloperoxidase.They have unpaired electrons in their outer orbitals and induce oxidative damage to cellular membranes and DNA.ROIs can kill microbes,but they also damage host cells.

Question 6

Which of the following is an enzymatic function of most types of inflammasomes?

Accepted Answer

There are several forms of inflammasomes,all of which are multiprotein complexes that form in the cytosol of cells in response to stimuli related to infection,toxins,or cell stress.When they form,inflammasomes incorporate an inactive precursor of the enzyme caspase 1,which is proteolytically cleaved to form active caspase 1,which goes on to proteolytically cleave an inactive precursor of IL-1F1F1F1S1F1F1F10 to generate active IL-1F1F1F1S1F1F1F10.

Question 7

For each of the descriptions of a component of the innate immune system in questions ,select the term that best matches it from the list below (A-J).
-Plasma protein that serves as a soluble pattern recognition receptor binding to microbial cells but not to mammalian cells

Accepted Answer

Mannose-binding lectin is a C-type lectin found in the serum that binds microbial surface carbohydrates with terminal mannose residues and mediates phagocytosis and activation of the lectin complement pathway.

Question 8

The signaling pathways triggered by Toll-like receptors typically result in activation of which of the following pairs of transcription factors?

Accepted Answer

The predominant signaling pathway used by Toll-like receptors (TLRs)results in the activation of the NF-F1F1F1S1F1F1F10B and immune regulatory factors (IRFs),which regulate promote expression of inflammatory genes and type 1interferon genes,respectively.T-bet and GATA-3 are transcriptional regulators involved in helper T cell differentiation.Fos is a component of AP-1,and STAT-6 is a transcription factor activated by IL-4 binding to cells.Lck is not a transcription factor,but rather a tyrosine protein kinase involved in antigen-receptor signaling in T cells.

Question 9

For each of the descriptions of a component of the innate immune system in questions ,select the term that best matches it from the list below (A-J).
-Broad-spectrum antibiotic present in the skin and in neutrophil granules;its synthesis is increased in response to inflammatory cytokines

Accepted Answer

Defensins are a family of vertebrate antimicrobial peptides found in epithelial barrier cells and neutrophil granules.They are toxic to a wide variety of microorganisms and may work by perturbing the permeability of limiting membranes of microbes.

Question 10

For each of the descriptions of a component of the innate immune system in questions ,select the term that best matches it from the list below (A-J).
-Acute-phase reactant produced by the liver and released into blood

Accepted Answer

C-reactive protein,a member of the pentraxin family of plasma proteins,is an acute phase reactant that is rapidly up-regulated by hepatocytes in response to inflammatory cytokines,such as interleukin (IL)-1,IL-6,and tumor necrosis factor-F1F1F1S1F1F1F10.

Question 11

Which of the following comparisons of the innate and adaptive immune systems is FALSE?

Accepted Answer

Innate immune system receptors are encoded by germline genes that have evolved to recognize microbial structures or molecules produced by stressed self,and therefore there is little chance of innate immune responses to normal self.Because the specificities of adaptive immune system receptors (Ig or T cell receptor molecules)are randomly generated by somatic recombination and junctional-diversity mechanisms,there is a greater chance that the adaptive immune system receptors may recognize normal self molecules,leading to autoimmunity.Mechanisms of tolerance minimize this possibility,but these mechanisms can fail.The adaptive immune system receptors can recognize nonmicrobial structures.Although most innate immune system receptors recognize microbial structures,some Toll-like receptors and activating receptors of natural killer cells do recognize nonmicrobial self proteins expressed by stressed,damaged,or infected cells.Memory is a major property of the adaptive but not the innate immune system.

Question 12

Which of the following statements about the innate immune system is NOT true?

Accepted Answer

Innate immunity is the first line of defense against infections,yet many pathogenic microbes have evolved strategies to resist innate immunity.Adaptive immunity,being more potent and specialized,plays a critical role in defending against these virulent microbes.Innate immunity is the phylogenetically oldest mechanism of microbial defense,and it is present in all multicellular organisms,including plants and insects.Studies have shown that hampering effector mechanisms of innate immunity renders hosts much more susceptible to infection,even with a functional adaptive immune system.It is also true that,like the adaptive response,the innate immune response consists of recognition,activation,and effector phases.Although it provides the initial,rapid response against microbes,innate immunity can influence adaptive immune responses to tailor them against particular microbes.

Quiz 7: Innate-Immunity

Toll-like receptors and other receptors are potent activators of various components of the innate immune system.All of the following proteins are expressed in response to signaling by these receptors EXCEPT:

Cytosolic DNA sensors are a large group of molecules that detect microbial dsDNA in the cytosol of infected cells,and situate innate responses.Most of these sensors signal though a pathway that includes which protein?

For each of the descriptions of a component of the innate immune system in questions ,select the term that best matches it from the list below (A-J) . -Produced by B-1 cells,protects against microbes that succeed in penetrating epithelial barriers

For each of the descriptions of a component of the innate immune system in questions ,select the term that best matches it from the list below (A-J) . -Superoxide anion,hydroxyl radical,or hydrogen peroxide,produced by activated phagocytes

Which of the following is an enzymatic function of most types of inflammasomes?

For each of the descriptions of a component of the innate immune system in questions ,select the term that best matches it from the list below (A-J) . -Plasma protein that serves as a soluble pattern recognition receptor binding to microbial cells but not to mammalian cells

The signaling pathways triggered by Toll-like receptors typically result in activation of which of the following pairs of transcription factors?

For each of the descriptions of a component of the innate immune system in questions ,select the term that best matches it from the list below (A-J) . -Broad-spectrum antibiotic present in the skin and in neutrophil granules;its synthesis is increased in response to inflammatory cytokines

For each of the descriptions of a component of the innate immune system in questions ,select the term that best matches it from the list below (A-J) . -Acute-phase reactant produced by the liver and released into blood

Which of the following comparisons of the innate and adaptive immune systems is FALSE?

Which of the following statements about the innate immune system is NOT true?