Innate Immunity

Question 1

What cells are important in innate immunity?

Answer 1

Neutrophils, macrophages, dendritic cells, natural killer cells

Question 2

What positively charged antimicrobial peptides are maintained in epithelial cells and neutrophils?

Answer 2

Defensins

Question 3

The innate immune response displays what two types of barriers?

Answer 3

Physical & chemical

Question 4

How do innate immune cells recognize pathogens and become activated to carry out their numerous functions?

Answer 4

Pattern Recognition Receptors (PRRs) on innate cells non-specially recognize pathogen-associated molecular patterns (PAMPs) on pathogens.

Question 5

What are the three types of PRRs on innate cells and where are they located?

Answer 5

C-type lectin receptors - extracellular

TLRs - intracellular/extracellular

NOD-Like receptors - intracellular/cytoplasmic

Question 6

Carbohydrates are recognized by what PRR?

Answer 6

C-type lectin receptors

Question 7

What TLR recognizes LPS on G- bacteria?

Answer 7

TLR-4

Question 8

What TLRs are located extracellularly?

Answer 8

TLR-1, TLR-2, TLR-4, TLR-5, TLR-6

Question 9

TLR-1, TLR-2, and TLR-6 recognized what ligands?

Answer 9

Peptidoglycan and lipoproteins on G+

Question 10

What TLR recognizes flagellin?

Answer 10

TLR-5

Question 11

What TLRs recognize viruses?

Answer 11

TLR-3 - dsRNA
TLR-7, TLR-8 - ssRNA

Question 12

CpG DNA in bacteria are recognized by which TLR?

Answer 12

TLR-9

Question 13

What cytokines increase inflammation and enhance the innate immune response?

Answer 13

TNF, IL-1. IL-6, IL-12

Question 14

What cytokines are released by macrophages?

Answer 14

IL-1, IL-6, IL-8, IL-12, TNF alpha

Question 15

IL-12, which is released by macrophages, serves what role?

Answer 15

Activates NK cells

Question 16

What cytokine released by macrophages recruits neutrophils?

Answer 16

IL-8 (CXCL-8)

Question 17

Which cytokines induce fever?

Answer 17

IL-1, IL-6

Question 18

What is the function of IL-1?

Answer 18

Activation of the endothelium & lymphocytes. Also induces fever

Question 19

What is the function of TNF alpha?

Answer 19

Activation of the epithelium and increase of vascular permeability

Question 20

What cytokine triggers local containment of infection, but may cause shock when released systemically?

Answer 20

TNF alpha

Question 21

What is the process by which leukocytes enter tissues from the blood?

Answer 21

Leukocyte Rolling & Migration

Question 22

What receptors are present on macrophages, neutrophils, and dendritic cells that enable phagocytosis?

Answer 22

Complement receptors & Fc receptors

Question 23

What enzymes are used by phagocytes for phagocytosis?

Answer 23

NADPH oxidase - reactive oxygen species

& inducible nitric oxide synthase (iNOS) - reactive nitrogen species

Question 24

Where are MHC I receptors expressed? What is their function?

Answer 24

Expressed on all nucleated cells to present antigens to CD8 T Cells

Question 25

What cells display MHC II receptors? What is their function?

Answer 25

Present on professional phagocytes and antigen-presenting cells to present antigens to CD4 T cells

Question 26

Neutrophils phagocytize pathogens using reactive oxygen species. If a pathogen is catalase +, how will that affect phagocytosis?

Answer 26

Catalase breaks down H2O2 so there will be a decrease in pathogen vulnerability to phagocytosis by neutrophils

Question 27

How do macrophages differ from neutrophils?

Answer 27

Neutrophils - exist in blood, short-lived, first responders, phagocytosis by ROS, extracellular traps Macrophages - exist in tissues, longer-lived, phagocytosis by NOS, cytokine release, antigen presentation, ingestion of necrotic host cells

Question 28

How does the function of dendritic cells differ from that of neutrophils and macrophages?

Answer 28

Dendritic cells phagocytize pathogens for the purpose of antigen presentation to T cells.

Question 29

How are virus-infected cells primarily killed?

Answer 29

By Natural Killer cells

Question 30

How are NK cells activated?

Answer 30

Activation receptors - antibody-coated cells, lectins, viral hemagglutinins Inactivation receptors - MHC I

Question 31

A cell expresses less MHC I on the surface than typical. What might this be indicative of? What is the body's response?

Answer 31

Viral-infected and tumor cells express less MHC I than normal cells. NK cells recognize lower levels of MHC I expression and phagocytize the cell.

Question 32

How do phagocytes phagocytize pathogens?

Answer 32

The phagocyte ingests the pathogen in a phagosome. The phagosome and lysosome undergo phagolysosomal fusion. The pathogen is degraded in the phagolysosome by degrative enzymes that were stored in the lysosome.

Question 33

What are the primary pattern recognition receptors (PRRs) of PAMPS?

Answer 33

C-type lectin receptors, TLRs, NOD-like receptors

Question 34

Where are the PRRs located?

Answer 34

C-type lectin - extracellular TLRs - extracellular & intracellular NOD-like receptors - cytoplasm & intracellular