Innate Immunity

Question 1

Name the two different type of phagocytes of the innate immune system.

Answer 1

Macrophages/monocytes

Neutrophils

Question 2

Where are macrophages found?

Answer 2

Macrophages are long-lived leukocytes which are widely distributed in normal tissues.

Question 3

What is the most abundant type of white blood cell in circulation?

Answer 3

Neutrophils

Question 4

Are neutrophils found in normal tissue?

Answer 4

No- they are rarely found in normal tissue. They are only recruited following activation of other immune system components.

Question 5

What is opsonization?

Answer 5

The coating of particles by molecules that enhance recognition by phagocytes

The adaptive immunity can opsonize pathogens with antibodies.

The innate immune system can opsonize pathogens with proteins of the compliment system

Question 6

What is the life span of a neutrophil?

Answer 6

Short-lived

Question 7

What is a PAMP?

Answer 7

PAMP: Pathogen Associated Molecular Pattern

-epitope from foreign particle

Question 8

What is a DAMP?

Answer 8

DAMP: Damage Associated Molecular Pattern

-epitope of endogenous protein, from a damaged cell

Question 9

What is the innate immune system’s response to binding PAMPS and DAMPS with their PRRs?

Answer 9

The innate immune system upregulates their expression of pro-inflammatory cytokines and antimicrobial peptides

Question 10

Name four classes of PRRs

Answer 10

Toll-like receptors
NOD-like receptors
C-type lectin-receptors
Rig-I-like receptors

Question 11

Are all PRRs expressed on the cell surface?

Answer 11

No-depending on what they recognize, PRRs can be located extracellularly (for bacterial PAMPS), or in the cytosol (for viral infections etc)

Question 12

What do the C-type Lectin PRR’s recognize and bind?

Answer 12

Mannose (on bacterial glycoproteins)

Question 13

Compliment activation (by all three pathways) leads to what effector function?

Answer 13

Enhanced phagocytosis through recognition of the C3b deposited all over the pathogen surface

Question 14

How is the phagocytic function of dendritic cells different from other phagocytic cells?

Answer 14

Dendritic cells do not destroy the target, but rather preserve the microorganism material for presentation to the adaptive immune system

Question 15

What is the role of NADPH in the phagolysosome?

Answer 15

NADPH, present in the phagolysosome membrane is oxidized by NADPH oxidase causing respiratory burst of superoxide (O2-, H2O2, and OH-) causing death of engulfed microbes

Question 16

What two cells are the major antigen presenters to T cells?

Answer 16

Macrophages and dendritic cells

Question 17

Differentiate the origin of the epitopes presented by class I MHC from Class II MHC

Answer 17

Class I: endogenous proteins

Class II: exogenous proteins

Question 18

What are innate lymphoid cells? How are they different from B and T cells?

Answer 18

Lymphocytes by morphology, but different from T and B cells in that they

1) Lack RAG genes –> No DNA rearrangements
2) They lack myeloid/DC markers
3) THey are of lymphoid morphology

—-? Weird slide.

Question 19

What are the three different types of innate lymphoid cells?

Answer 19

ILC1, ILC2 and ILC3

They are differentiated by the cytokines produced

Question 20

Describe the cytokines produced by innate lymphoid cells type 1 (natural killer cells)

Answer 20

NK cells secrete the pro-inflammatory cytokines IFN-gamma and TNF

Question 21

What is the purpose of the innate immune system releasing cytokines and chemokines following binding of PAMPS/DAMPS by PRRs?

Answer 21

Activation of effector cells (mast cells, innate lymphoid lymphocytes) which can amplify the signal and activate the adaptive immune system

Question 22

What is the result of a problem with PRRs?

Answer 22

Failure of PRRs –> susceptibility to bacterial and viral infections. If the innate immune system is not activated, the adaptive immune system will not respond properly