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Zach- Immunology > Lecture 6: MHC Binding > Flashcards

Lecture 6: MHC Binding Flashcards

1
Q

What is required for a naive T cell to be activated?

A
  1. recognize the Ag at the TCR

2. binding of co-stimulatory and co-receptors

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2
Q

What process occurs once a T cell is activated?

A
  1. undergoes clonal expansion
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3
Q

What does Th1 cells do?

A
  1. release IFN-gamma to activate tissue macrophages
    - -rid intracellular microbes
  2. develop cytotoxic T cells
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4
Q

What do Th2 cells do?

A

1.help B cells proliferate into memory and plasma cells

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5
Q

What is secreted by Th2 to help B cell proliferation?

A
  1. IL-4
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6
Q

What does IL-4 do?

A
  1. secreted from Th2 cells to help B cell proliferate into memory and plasma cells
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7
Q

What is the TCR, found at the membrane, made of?

A
  1. alpha chain and beta chains

2. both form constant and variable regions

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8
Q

What is the Ag-binding site formed of?

A
  1. the constant and variable regions of the alpha, beta chains
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9
Q

Can T cells express gamma and delta chains on the TCR?

A

yes, poor understanding

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10
Q

What is known about the specificity of the gamma, and delta chain TCRs?

A
  1. broad specificity

2. bind to HSP and phospholipid Ag

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11
Q

What is the molecular weight of alpha chains in TCR?

A
  1. 50kDa
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12
Q

What is the molecular weight of beta chains in TCR?

A
  1. 39kDa
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13
Q

What is the location of the constant and variable regions on the TCR?

A
  1. constant region, located near the PM so it will always bind to the T cell
  2. variable regions is presented to the Ag binding site to provide different attachments for different Ag
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14
Q

What is CD3 and why is it significant to TCR?

A
  1. signaling complex of gamma, delta, espilon chains
  2. acts to help with APC presentation/binding to MHC
  3. therefore is a co-receptor to activate T cells
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15
Q

Th cells are restricted to recognizing peptides presented on what MHC class?

A

MHC II on the APC

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16
Q

Tc cells are restricted to killing cells presented on what MHC class?

A

MHC I

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17
Q

What type of Ag is able to bind peptides and is critical for Ag presentation?

A

human leukocyte Ag (HLA)

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18
Q

What are human leukocyte Ag (HLA)?

A

polymorphic genes that are the human equivalent of MHC class I and class II

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19
Q

Which class of HLA is expressed on all nucleated cells?

A

MHC class I

20
Q

HLA-A, HLA-B, HLA-C are all ___________

A

MHC class I genes that encode a polymorphic heavy chain

21
Q

What do the polymorphic heavy chains of class I HLA genes combine with?

A

Beta2-microglobulin

22
Q

What is the code for MHC class II human leukocyte antigen (HLA)?

A

-DP, -DR, -DQ

23
Q

Do MHC class II HLA genes contribute to peptide-binding groove?

A

yes, with use of alpha and beta chains

24
Q

How long is the amino acid sequence that MHC class I regions can bind? And MHC II?

A
  1. 8 to 10

2. 10 to 20

25
Q

In MHC class I, the peptide binding cleft is formed by______?

A

the polymorphic alpha chain, which also provides attachment to the PM

26
Q

In MHC class II, the peptide binding cleft is formed by __________?

A

both the alpha 1 and beta 1 complex units

27
Q

Which cells express MHC class I?

A

all nucleated cell

28
Q

Which cells express MHC II?

A
  • DC
  • Mononuclear phagocytes
  • B lymph
  • endothelium cells
  • thymic epithelium
29
Q

Peptide antigens that bind with MHC I molecules come from where and use what process to make it to this point?

A
  1. come from viruses that infect host cells

2. use endogenous pathway

30
Q

If a peptide Ag were to bind with MHC II, where is this Ag taken up from and what TCR interacts with it?

A
  1. taken up from environment via exogenous pathway

2. interacts with CD4+ T cells

31
Q

What effect will a Dendritic cell have on a Naive T cell if an Ag is presented?

A

The naive T cell will be activated, undergo clonal expansion, and differentiate into effector T cells

32
Q

Effector T cell binds with a macrophage, what is the end result?

A

The macrophage is activated and thus begins cell mediated immunity

33
Q

What happens if a B cell, with antigen, interacts with an effector T cell?

A

Causes B cell activation that produces antibodies, and therefore a humoral response.

34
Q

What ports of entry allows a microbial Ag to be transported to the regional lymph nodes?

A
  1. entrance via the skin
  2. the GI
  3. Respiratory tract
    - -DC capture and transport them to regional LN
35
Q

What port of entry causes microbial Ag to be transported to the spleen?

A

Ag that enter the bloodstream

36
Q

Ag that enter the blood stream, and encounter APC, are transported where>

A

the spleen

37
Q

Ag the enter via the skin, GI, or respiratory tracts, or other mucosal tracts except the eye are transported where?

A

To regional lymph nodes

38
Q

What is IFN-gamma able to produce?

A

stimulates the MHC II expression and increases activation of CD4+ cells

39
Q

What compounds are able to activate MHC I, and therefore activation of CD8+ T cells?

A

IFN-gamma and Type I interferons

40
Q

What is HLA-DM?

A

provides the most relevant Ag for the APC to present

41
Q

What are the 3 functions of HLA-DM?

A
  1. dissociates CLIP from the peptide binding groove of MHC II
  2. Stabilizes and prevents degradation of empty MHC II
  3. Helps binding of Ag fragments to the binding groove
42
Q

Draw out the pathways for MHC I and MHC II uptake and processing of microbe

A

yes

43
Q

Are DC able to present Ag via MHC I pathways?

A

yes this is cross presentation

44
Q

What is the process of cross presentation?

A
  1. infected host cell is taken up by DC
  2. The viral Ag enters the DC cytosol
  3. MHC I are bound with the viral Ag peptide
  4. this is presented to CD8 cells with a costimulator
  5. T cells generate effector response
45
Q

What is an immunodominant peptide?

A

Any of the peptides having a strong affinity for binding with class I or II histocompatibility antigens and for stimulating a response by T lymphocytes.

46
Q

How are immunodominant peptides produced and what are the benefits of them?

A

Immunodominant peptides are produced by antigen processing, are expressed on the surface of macrophages and other antigen-presenting cells, and may be useful both in desensitizing people to allergens and in vaccine production.

Zach- Immunology (10 decks)

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