Lecture 6 - Antigens & MHC

Question 1

what are antigens

Answer 1

a foreign substance that will bind to MHC receptors

Question 1

What are MHC

Answer 1

a set of genetic loci that helps immune cells differentiate foreign from self

Question 2

What limits the innate immune system’s efficacy

Answer 2

Limited specificity, less potent, lacks memory

Question 3

What cells express PRRs

Answer 3

innate immune cells

Question 4

How is the adaptive immune system specific

Answer 4

employs antigen-specific lymphocytes (B and T)

Question 5

How is the adaptive immune system systemic

Answer 5

targeted and reaches all parts of the body versus local responses

Question 6

How does the adaptive immune system have memory

Answer 6

once exposed to an antigen, the animal will make a stronger and more immediate response to it via antibodies and memory cells

Question 7

Epitope

Answer 7

site on an antigen recognized by specific receptors

Question 8

Immunogens

Answer 8

antigens that induce an immune response after binding

Question 9

T/F: ALL immunogens are antigens but NOT ALL antigens are immungoens

Answer 9

True

Question 10

What makes an antigen “good”

Answer 10

the ability for it to be recognized by the immune cells

Question 11

Whata are the characteristics of a “good” antigen

Answer 11

Large, complex, moderate degradability, foreign

Question 12

What are microbial agents

Answer 12

bacterial or viral antigens

Question 13

What are non-microbial agents

Answer 13

cell-surface, food-derived, inhaled, injected, etc.

Question 14

what are autoantigens

Answer 14

a trigger that is self (autoimmune)

Question 15

What are haptens

Answer 15

small, non-immunogenic proteins/molecules used to stimulate an immune response after binding to carrier proteins

Question 16

What is an Antigen Presenting Cell

Answer 16

immune cell which presents antigens on their cell surface for the activation of T cells

Question 17

What cell is the bridge between the innate and adaptive immune systems

Answer 17

dendritic cells

Question 18

What cells are APCs

Answer 18

Dendritic cell, B cell, Macrophage

Question 19

What do the dendritic processes contribute to in DC cells

Answer 19

adhesion and communication with T cells, antigen trapping

Question 20

What are the four classes of DCs

Answer 20

1. Classical
2. Follicular
3. Langerhans
4. Plasmacytoid

Question 21

What does Classical DC do

Answer 21

detect and capture antigens in the local environment and migrate to the lymph (The Golden Trio)

Question 22

What does the Langerhans Cells do

Answer 22

detect antigens present in microbes of the skin and create a local response

Question 23

What do Follicular DCs do

Answer 23

present antigens to B cells to activate them

Question 24

What do Plasmacytoid DCs do

Answer 24

Release Type I and Type III interferons to trigger viral infection response

Question 25

Pinocytosis

Answer 25

drink/intake of soluble material

Question 26

T/F: Macrophages present antigens to naive t cells

Answer 26

False - present to already activated T cells

Question 27

Identify APCs for exogenous antigens

Answer 27

DC

Question 28

What is AG processing

Answer 28

native antigen is trimmed into smaller immunogenic fragments by the intracellular machinery of APCs

Question 29

Activated (mature) DCs express high levels of what

Answer 29

MHC molecules and chemo secretions

Question 30

Class I MHC

Answer 30

Most immune cells present to cytotoxic T cells (C8)

Question 31

Class II MHC

Answer 31

B cells, macrophages, DCs, T cells present to helper T cells (C4)

Question 32

What is the structure of MHC Class I

Answer 32

alpha chain (3 domains) bound to B2-microglobulin

Question 33

T/F: MHC Class I binds shorter antigens than Class II

Answer 33

True

Question 34

What is the structure of MHC Class II

Answer 34

alpha and beta chains

Question 35

Summarize how exogenous antigens become presented and recognized

Answer 35

1 - APCs endocytose 2- digested by proteases 3- antigens binds to MHC class II endosomally 4 - carried to cell surface 5 - recognized by T helper cells

Question 36

Summarize how endogenous antigens are presented and recognized

Answer 36

1 - antigens are fragmented by ubiquitination 2 - pass into ER lumen 3 - bind to MHC Class I 4 - carried to cell surface 5 - recognized by cytotoxic T cells

Question 37

Summarize exogenous antigens

Answer 37

- bacteria, allergens - captured and degraded by APC - MHC II presents - CD4+ (helper) T cells

Question 38

Summarize endogenous antigens

Answer 38

- viruses, tumors - processing by affected cell - MHC I presents - CD8+ (cytotoxic) T cells

Question 39

What is cross-presentation?

Answer 39

When dendritic cells present exogenous antigens with MHC class I

Question 40

What are superantigens?

Answer 40

Bind to outer edge of MHC-TCR complex T cells are stimulated in non-specific way - CD4+ T cells produce large amounts of cytokines

Question 41

T/F: too little MHC creates autoimmune conditions

Answer 41

False - too many

Question 42

What are the two components of MHC genes

Answer 42

1. multiple gene families (no rearrangements) 2. Gene polymorphism (variable alleles)

Question 43

T/F: MHC heterozygous individuals respond to a greater range of antigens

Answer 43

True

Question 44

How many different MHC are there to provide resistance to disease and autoimmune effects

Answer 44

6