Lecture 6 - Antigens & MHC Flashcards

1
Q

what are antigens

A

a foreign substance that will bind to MHC receptors

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1
Q

What are MHC

A

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

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2
Q

What limits the innate immune system’s efficacy

A

Limited specificity, less potent, lacks memory

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3
Q

What cells express PRRs

A

innate immune cells

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4
Q

How is the adaptive immune system specific

A

employs antigen-specific lymphocytes (B and T)

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5
Q

How is the adaptive immune system systemic

A

targeted and reaches all parts of the body versus local responses

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6
Q

How does the adaptive immune system have memory

A

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

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7
Q

Epitope

A

site on an antigen recognized by specific receptors

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8
Q

Immunogens

A

antigens that induce an immune response after binding

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9
Q

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

A

True

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10
Q

What makes an antigen “good”

A

the ability for it to be recognized by the immune cells

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11
Q

Whata are the characteristics of a “good” antigen

A

Large, complex, moderate degradability, foreign

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12
Q

What are microbial agents

A

bacterial or viral antigens

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13
Q

What are non-microbial agents

A

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

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14
Q

what are autoantigens

A

a trigger that is self (autoimmune)

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15
Q

What are haptens

A

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

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16
Q

What is an Antigen Presenting Cell

A

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

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17
Q

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

A

dendritic cells

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18
Q

What cells are APCs

A

Dendritic cell, B cell, Macrophage

19
Q

What do the dendritic processes contribute to in DC cells

A

adhesion and communication with T cells, antigen trapping

20
Q

What are the four classes of DCs

A
  1. Classical
  2. Follicular
  3. Langerhans
  4. Plasmacytoid
21
Q

What does Classical DC do

A

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

22
Q

What does the Langerhans Cells do

A

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

23
Q

What do Follicular DCs do

A

present antigens to B cells to activate them

24
Q

What do Plasmacytoid DCs do

A

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

25
Q

Pinocytosis

A

drink/intake of soluble material

26
Q

T/F: Macrophages present antigens to naive t cells

A

False - present to already activated T cells

27
Q

Identify APCs for exogenous antigens

A

DC

28
Q

What is AG processing

A

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

29
Q

Activated (mature) DCs express high levels of what

A

MHC molecules and chemo secretions

30
Q

Class I MHC

A

Most immune cells

present to cytotoxic T cells (C8)

31
Q

Class II MHC

A

B cells, macrophages, DCs, T cells

present to helper T cells (C4)

32
Q

What is the structure of MHC Class I

A

alpha chain (3 domains) bound to B2-microglobulin

33
Q

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

A

True

34
Q

What is the structure of MHC Class II

A

alpha and beta chains

35
Q

Summarize how exogenous antigens become presented and recognized

A

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

36
Q

Summarize how endogenous antigens are presented and recognized

A

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

37
Q

Summarize exogenous antigens

A
  • bacteria, allergens
  • captured and degraded by APC
  • MHC II presents
  • CD4+ (helper) T cells
38
Q

Summarize endogenous antigens

A
  • viruses, tumors
  • processing by affected cell
  • MHC I presents
  • CD8+ (cytotoxic) T cells
39
Q

What is cross-presentation?

A

When dendritic cells present exogenous antigens with MHC class I

40
Q

What are superantigens?

A

Bind to outer edge of MHC-TCR complex

T cells are stimulated in non-specific way - CD4+ T cells produce large amounts of cytokines

41
Q

T/F: too little MHC creates autoimmune conditions

A

False - too many

42
Q

What are the two components of MHC genes

A
  1. multiple gene families (no rearrangements)
  2. Gene polymorphism (variable alleles)
43
Q

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

A

True

44
Q

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

A

6