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micro > Immunology Exam 3 > Flashcards

Immunology Exam 3 Flashcards

Exam Study

1
Q

What is an Epitope

A

The smallest subunit of antigens

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2
Q

Define linear epitope

A

Exist within the Amino acids sequence. Even if structure is denatured. 8-15 residues long

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3
Q

Define discontinuous epitope:

A

Not in the primary sequence shapes formed by secondary and tertiary structures

( other chains coming together)

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4
Q

Define immunodominance:

A

Some epitopes are better at creating an immunolog response then other

        Can be animal specific but usually specific specific.
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5
Q

Describe the characteristics of a molecule that determine antigenicity

1 of 3

A

Immune system recognizes small portion of macromolecules ( not the whole structure)

  1. Discrimination between self and nonself
  2. Occurs by recognition of molecular shape
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6
Q

Describe the characteristics of a molecule that determine antigenicity

2 of 3

A

Antigen is molecular shpat that can be recognized by antibody or lymphocytes

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7
Q

Describe the characteristics of a molecule that determine antigenicity

3 of 3

A

An epitope is the smallest subunit of an antigen.

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8
Q

What is the difference between an antigen and an immunogen

A
  1. Antigen: molecular shpate that can be recognized by antibodies/ lymphocytes surface receptors
  2. Immunogenic: if it stimulates an acquired immune response by itself
  3. Immunogens are antigenic but not all antigens are immunogenic has to follow all the characterisics of an antigen
  • Size is greater the 1,000 DA
  • Lots of peptides.. if smaller will be recognized but no immune response will be caused
  • Complex
  • Greater vaiety of epitopes
  • Knows self from non self
  • Ridity
  • Epitopes must maintain shape to generate a response
  • Degrabadility:
  • Large molecures must be broken down into individual epitopes to initiate response
  • Antigenicity : Proteins > carb> lipids and nucleic acids > metals and plastics
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9
Q

Why does cross-reactivity occur?

A
  • Very simialru epitopes but are found on very dissimilar molecules or on evolutionaily similar molecules
  • Antibodies formed in an immune response to one immunogen may recognize epitopes on another molecule
  • Cross- immunognes: same or similar epitope found in dissimilar molecules can afford protective immunity to one when primary exposure is to the other: human meslase virus vacc for canian distemper
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10
Q

Vocabulary:

Co-expression:

A

Mult genes being expressed at the same time

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11
Q

Endogenous antigen:

A

Antigen coming within presenting cell ( self) exogenous antigen

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12
Q

What is the genetic organization of the

MHC genes. (generally)

A
  • MHC 1: 3 genes that are coexpressed, with 2 allels per individual ( 2 copies of each)
    • Could have up to 6 different genes on one cell surface
    • Inbreding lowers diversity of MHC1 genes
    • Pseudogense
  • MCH2: 17 genes, highly polymorphic – several coex[ressed genes in an individual many alleles in the population
  • Has proteasome TAP 1, 2
  • MHC3:
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13
Q

What are the functions of class I vs. class II MHC receptors and their cellular distributions

A
  • MCH 1: found on all nucleated cells, highly expressed on most cell of immune system, CD8
  • MHC 2: found on APC: Dendritic cell, B lymphocytes, monocytes
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14
Q

How is MHC polymorphism important for individuals and populations.

A
  • Polymorphism: having the ability to binding different peptide forms on the MHC molecule.
  • This leads to varying difference of sickness/reaction to pathogen.
  • In a heard setting if one person/animal got sick due to polymorphism other people/animals would be most likely about to recognize and bind the pathogen there fore not getting sick. Then the disease wouldn’t spread through the heardà
  • Therefore polymorphism is very important!
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15
Q

What is the distribution, life cycle,

and functions of dendritic cells

A
  • Found under skin, mucosal surface, lymphnoes
  • NOT in brain, eyes and testies
  • Starts in the bone marrow à monocoyie or lymphoid à if they don’t bind to an antigen will die within 4-5 days
  • Immature DC ( one not bound to an antigen before)
  • Expresses HIGH durface Fc receptors ( if bound to an antibodie), Mannose and chemokine receptors, TLRS 2 & 4, intracellular MHC 2
  • LOW: surface MHC 2, costimulatory Il12
  • Mature: ( once bound to an antigen) boosts antigen presentation functions
  • Expresses HIGH: MHC 2 surface receptors, costimulatory IL-12
  • Migrate to secondary lymphoid organs to present to T cells
  • Cells are polarized: have specialized functions
    1. Extra vs intra
    1. Humoral ( extra cellular) vs. cell mediated ( intracellular)
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16
Q

Vocabulary:

Endogenous antigen:

A

Antigen coming within presenting cell ( self) exogenous antigen

17
Q

Vocabulary:

Co-expression:

A

Mult genes being expressed at the same time

18
Q

What is cross-priming?

A
  • If an peptide escapes from an endosome vesicle it would be in the cytosol à go through proteasome à bind to class I and become express on MHC 1
19
Q

What are the inherited determinants of disease resistance and susceptibility related to antigen presentation?

A
  • TAP ( transport antigen protein) and MHC: determines ones potential for immune response
  • However whether exogenous or endogenous antigen NEEDS to be bound to an MHC molecule to trigger an immune response
20
Q
  1. Distinguish primary from secondary lymphoid tissues
  2. Which tissues fall into each category.

Primary:

Develop early in fetal life
Removal causes loss of lymphocytes and lymphocyte function à immune impaired
Sites of foregin antigen independent lymphocytes development and differentiation

Secondary:

Develop later in gestation
Removal will little effect on immune responses
Foregin antigen dependent lymphocyte development and differentiation

Where lymphocytes function to create an antigen- specific imuune response

A

Be able to distinguish primary from secondary lymphoid tissues and know which tissues fall into each category.

  • Primary:
  • Develop early in fetal life
  • Removal causes loss of lymphocytes and lymphocyte function à immune impaired
  • Sites of foregin antigen independent lymphocytes development and differentiation
  • Secondary:
  • Develop later in gestation
  • Removal will little effect on immune responses
  • Foregin antigen dependent lymphocyte development and differentiation
  • Where lymphocytes function to create an antigen- specific imuune response
21
Q

Describe the movements of a lymphocyte

from birth to death.

A
  • Start in the bone marrow à travel through out the body in blood, vessels and lymphatic
  • Cells have adhesions protein which tells them which target to go to
  • Different adhesion protein is expressed depending on stage of development
  • Cells die within 3-4 days in the tissue if not exposed to an antigen

(Side note: Global response directed at antigen encountered locally is from)

  1. Circulation of lymphocytes
  2. Secretion of antibodies (from plasmid cells) à create one characteristic of specific immunity
22
Q

Describe two main phases of lymphocyte development

  • What is happening
  • Where these events occur.
A
  • Part one: foreign antigen – independent phase
  • Generation of diversity
  • Replication and progressive differentiation à NEW surface proteins
  • Random reorganization of antigen binding sites of surface receptors ( either BCR or TCR)
  • This creates generate antigen binding diversity
  • Cells are educated à removed if bind to self
  • Develops tolerance
  • Part two: foreign antigen- dependent phase
  • Clonal selection
  • Replication and further differentiation into effector cells
  • Requires antigen recognition of T h cells
23
Q

Explain the functionally important cell-surface receptors of B and T lymphocytes.

A

B- cells

  • BCR: interaction with antigen
  • igM monomer à same antigen binding specificity as the antibodies that b cell is capable of producitn
  • Rectors for interleukins: mediate B cell response
  • IL 2R, 4R, TFG-bR, IFN-yr
  • MHC 2: B cell function in capture and resentation of EXOGENOUS ANTIGENS

T-cells

  • TCR: is a dimer may be a/b or y/d
  • CD3: protein complex required for signal transfuction via TCR
  • All cells have CD3
  • CD4: specific marker of T helper cells à MHC 2 molecules and HIV, exogenous
  • CD8: Specific Cytolytic T lymph à MHC 1, nucleated cells endogenous
  • Interleukins: mediate T cell response
24
Q

Know the 3 types of antigen-sensitive lymphocytes

&

The effector cell phenotypes each one obtains when activated.

A
  1. Tc cell
  2. TH cell
  3. Bcell
25
Q

Describe structure & distribution of B cell receptors including

The associated signal transduction complexes.

A
  • Membrane anchored IgM monomer
  • 200-500k identical copies only bind one type of epitope ( antigen binding domain)
  • u heavy chain with transmebrane domain
  • Antigen binding to BCR doesn’t depend on processing à BCR binds to native epitopes
  • Unlike B cell it doesn’t need to be linear epitope
  • No MHC receptors so it can bind to what ever it see: Carb, lipids
  • Doesn’t need to strictly attach peptides
  • Signal transducing component is paired transmembrane heterodimers which associate with CH4 and trasnmembrane domains of heavy chains
26
Q
A

micro (2 decks)

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