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Immunohematology and Serology > Chapter 3 - Antigens, Epitopes, and Immunogenicity > Flashcards

Chapter 3 - Antigens, Epitopes, and Immunogenicity Flashcards

1
Q

State and Site: Immunization protocols

  • what are the two ways that an antigen can elicit responses after inoculation?
  • why might multiple inoculations be necessary?
A
  • Particulate antigens elicit responses after inoculation by intracutaneous or intravenous routes at a broad range of doses
  • Soluble antigens may require repeated immunizations
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2
Q

Adjuvant

  • What is it?
  • What does it do and how does it do it?
  • what immune response does it generate?
A
  • Increase response to an immunogen
  • Stimulate localized inflammatory reaction at site of injection
  • Slow release of the antigen
  • Recruits phagocytic and inflammatory cells
    • Better uptake of the antigen
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3
Q

Adjuvant

  • what are two types?
  • give examples of those types
A
  • Types:
    • Aluminum salts
    • Mineral oil and they often contain bacteria or bacterial products
  • Examples:
    • Alum
    • Freund’s Adjuvant (a mineral oil and water mixture either free or containing bacterial products)
    • lipopolysaccharide (LPS)
    • Muramyldipeptide
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4
Q
  • What is a linear epitope?

- What is it related/not related to?

A
  • Related to amino acid sequence of an antigen

- Not related to three-dimensional structure

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5
Q

What part of an antigen dictates the conformational epitope structure?

A
  • Depends on antigen’s three-dimensional structure
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6
Q

Describe the region on the B cells that recognizes and binds epitopes:

  • # of amino acids?
  • # of sugars?
A
  • 6–15 amino acids

- 2–7 sugars

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7
Q
  • What size peptides can MHC I molecules bind to?

- What size peptides can MHC II molecules bind to?

A
  • Class I MHC molecules can bind peptides of 8–10 amino acids
  • Class II can accommodate peptides of 13–18 amino acids
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8
Q

Cross-Reactivity

  • characteristics (2)?
  • what happens?
A
  • Nature is repeating patterns
  • Epitopes may be shared by different antigens
  • Reaction of an antibody with an antigen other than the one that induced its formation
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9
Q

Cross-Reactivity

  • why does it occur (2)?
  • what are some common tests where this might happen?
A
  • Occurs because
    • The exact same epitope is on the molecule
    • Or a very similar to the epitope
  • Use caution to not misdiagnose patient
    • FSH, HCG, LH
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10
Q

Cross-Reactivity

- when is it a good thing?

A
  • Can be helpful for vaccines

Tetanus toxin and tetanus toxoid

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11
Q

Major Histocompatibility Complex (MHC)

- What differentiates Class I & II from Class III?

A
  • Only Class I, Class II MHC genes play a direct role in immune responses
  • Class III encodes for cytokines and complement and other soluble proteins
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12
Q

Major Histocompatibility Complex (MHC)

- what are its limitations (2)?

A
  • Limited by inherited haplotypes

- Individuals may respond differently to a particular antigen

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13
Q

Major Histocompatibility Complex (MHC)

  • what are HLA?
  • what do they do?
A
  • Human MHC antigens involved in immune response called Human Leukocyte antigens
  • Encode for proteins on the antigen presenting cell which present the antigen to a T-cell
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14
Q

Major Histocompatibility Complex (MHC)

  • define polymorphic
  • how are the alleles inhereted (number-wise)
  • how are they expressed (dominant, co-dominant, recessive…)
  • how many different sets can be inherited?
A
  • MHC haplotypes are highly polymorphic:
    • Genes have many alternate forms
  • These alleles are inherited as sets
    • One set of alleles from each parent
  • – Co-dominantly expressed: the products of both sets of genes are expressed on cell surfaces
  • Four different sets that can be inherited
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15
Q

Major Histocompatibility Complex (MHC)

- What happens when there is a hole in the repertoire?

A
  • Hole in repertoire, an individual fails to respond to a certain antigen
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16
Q

Major Histocompatibility Complex (MHC): Class I

  • what type of molecules to they present?
  • what type of cells is this class found on?
  • what region of the MHC encodes these?
  • to what type of cell is the antigen presented and what happens to the antigen?
A
  • endogenous antigens (from inside the cell as in an infected cell)
    • Those in an infected cell
  • Found on all nucleated cells
  • Encoded by A, B, and C regions of the MHC
  • Present antigen to cytotoxic T cells
    • To kill infected cell
17
Q

Major Histocompatibility Complex (MHC): Class II

  • what type of molecules to they present?
  • what type of cells is this class found on?
  • what region of the MHC encodes these?
  • to what type of cell is the antigen presented?
A
  • Recognize exogenous antigens (from the environment)
  • Found on antigen-presenting cells
  • Encoded by the DR, DP, and DQ regions
  • Present antigen to helper T cells
18
Q

T-Cell Receptors

  • what do they do?
  • what do they need to do it?
  • what are those regions composed of?
A
  • T cells can recognize a variety of different antigens
  • Achieved via T-cell receptors (TCRs)
  • Composed of two heterodimers (either alpha,beta or gamma,delta) covalently linked by a single disulfide bond
19
Q

T-Cell Receptors

  • CD marker?
  • what does that marker do?
A
  • Associated with CD3

- - Which signals and activates the cell after antigen binding

20
Q

Antigen Presentation

  • what CD markers tend to be on these T cells?
  • what do these T cells do once activated (4)?
A
  • Activate CD4+ (class II) and CD8+ (class I) T cells
  • Accessory or antigen-presenting cell binds a particular antigen
  • Internalizes antigen
  • Processes antigen biochemically
  • Presents antigen to T cell in Class I or Class II molecule
21
Q

Antigen Presentation

  • where does Class I get the antigen added to the MHC?
  • where does Class II get the antigen added to the MHC?
A
  • Class I transported to Golgi compartment after synthesis

- Class II goes to endosomal compartment after invariant chain removal

22
Q

Antigen Presentation

- what happens to Class I and II once they segregate in the cell after synthesis?

A
  • Class I and class II segregate
    • Class I interact with antigen peptides
    • Class II are complexed to the invariant chain (Ii)
23
Q
  • What are some examples of natural haptens?

- What are some examples of artificial haptens?

A
  • natural: penicillin, poison ivy

- artificial: vaccines

24
Q

The Exquisite Specificity of the Immune System: Haptens

  • what type of reactions are these used to study?
  • what did Karl Landsteiner’s experiment discover?
A
  • Used to study the specificity of antigen–antibody reactions
  • Karl Landsteiner’s experiment produced an understanding that the diversity of an immune response can be immense

Immunohematology and Serology (8 decks)

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