Lecture 1 - Overview of Immune Response

Question 1

What is an epitope?

L1 S15

Answer 1

The portion of a antigen that an antibody binds to.

Also called antigenic determinant.

Can be as small as 3-6 amino acids or 5-6 sugar residues.

Question 2

What is an immunogen?

L1 S16

Answer 2

An antigen that generates an immune response.

Question 3

All immunogens are antigens but not all antigens are immunogens.

L1 S16

Answer 3

Know this

Some substances that are bound by antibodies do not stimulate an immune response and therefore is not an immunogen.

Question 4

What is innate immunity and what are its characteristics?

L1 S17+27

Answer 4

Initial response to an infection, particularly new exposures

• rapid in response
• produces the same response
• recognizes common Ags
• produces acute inflammation
• has some specificity
• no memory

Question 5

What is adaptive immunity and what are its characteristics?

L1 S17

Answer 5

Targeted response to a particular infection that has been seen previously

• takes time to develop
• highly specific
• remembers antigens that have been previously encountered

Question 6

What are the components of the innate immune system and what does each component do?

L1 S19

Answer 6

Antimicrobial peptides:
-target pathogenic microorganisms

Complement:
-plasma proteins that enhance the ability of Abs and phagocytic cells to clear pathogens

Acute phase protiens (APPs):
-blood proteins that change concentration in response to injury, infection, burns, or inflammation

Cytokines:
-signal molecules that aid in communication of immune response

Chemokines:
-type of cytokines secreted by immune cells to induce chemotaxis

Phagocytes

Question 7

Differentiate between humoral and cell components of the immune system.

L1 S20

Answer 7

Humoral:
-components found freely in blood (complement, APP, cytokines, chemokines, etc.)

Cell:
-cells involved involved in immune response

Question 8

What are the components of the adaptive immune system?

L1 S21

Answer 8

Humoral:

• antibodies
• cytokines

Cell:
-B and T lymphocytes

Question 9

What is one of the main ways in which the innate immune system supports the adaptive immune system.

L1 S24

Answer 9

Determines in the pathogen is intracellular or extracellular and provides this information to the adaptive immune system

Question 10

What are the main functions of cytokines?

L1 S15

Answer 10

• regulate growth and differentiation of immune cells

- activate effector functions of lymphocytes and phagocytes

Question 11

What are the main functions of phagocytes and what are the two main types of phagocytes?

L1 S29

Answer 11

Functions:

• RECRUITMENT of immune cells to site of infection
• RECOGNITION of microbes
• INGESTION of microbes
• DESTRUCTION of ingested microbes

Main types:

• Neutorphils/polymorphonuclear leukocytes (PMNs)
• Monocytes/macrophages

Question 12

What are the characteristics of neutrophils, where are the produced and what stimulates their production?

L1 S30-31

Answer 12

• multilobular nucleus
• most abundant WBC
• mediates earlier immune responses
• circulate in the blood for a few hours-days
• survives in tissues for 1-2 days

Originates from bone marrow and growth is stimulated from granulocyte colony-stimulating factor (G-CSF)

Question 13

What are the characteristics of monocytes/macrophages, where are the produced and what stimulates their production?

L1 S32-33

Answer 13

• monocytes found in blood stream and enter tissues to become macrophages
• clearance of cellular debris
• immune surveillance
• responds to infection
• resolves inflammation

Originates from bone marrow and growth is stimulated from monoocyte/macrophage colony-stimulating factor (M-CSF)

Question 14

How does the innate immune system discriminate between self and non-self?

What are examples of ways the body discriminates between self and non-self?

L4 S9

Answer 14

PRRs (pattern recognition receptors) recognize PAMPs (pathogen-associated molecular patterns).
These PAMPs have no structural similarly with self-Ags.

Prokaryotes start proteins with f-Met while eukaryotes don’t and mannose-tailed glycans are essential surface molecules for bacteria and viruses but not eukaryotes. These are PAMPs targeted by PRRs.

Question 15

What are TLRs and what are their functions?

L4 S23-24

Answer 15

Toll-like receptors; class of PRRs.

• expressed on/in immune cells
• trigger either NF-κB or IRF pathway (pro-inflammatory) using TRIF or MyD88 signaling

Activation of pro-inflammatory genes cause:

• activation of adaptive immune response
• antimicrobial response resulting in bacterial death
• host tissue damage through apoptosis

Question 16

What TLRs use the TRIF pathway and what TLRs use the MyD88 pathway?

L4 S22

Answer 16

Only TLR3 and TLR4 use TRIF pathway.

All TLRs, except TLR3 use MyD88 pathway.

*note that TLR4 uses both pathways

Question 17

What are lectin family receptors and what are their functions?

L4 S36-37

Answer 17

Class of SRRs

• recognize microbial surface carbohydrates (D-mannose, L-fucose, N-acetyl-D-glucosamine)
• mediates phagocytosis

Question 18

What are DAMPs and what causes them?

L4 S38

Answer 18

Damage associated molecular patterns

Necrotic cells release DAMPs (molecules that should not be found outside the cell) which are then recognized by immune cells and stimulate inflammation.

Question 19

What are NODs and what are their functions?

L4 S29-30

Answer 19

NOD-like receptors; class of PRR

• found in cytoplasm of immune cells
• forms signaling complex (inflammasome) that activates caspase-1
• caspase-1 activates IL-1β and IL-18 (proinflamatory cytokines)

NODs respond to microbial products, certain crystals, or decreased cytoplasms [K+]