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SFM Final Lectures > Shynra B and T cell questions > Flashcards

Shynra B and T cell questions Flashcards

1
Q

What does the constant region of the heavy chain dictate?

A

Isotype

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2
Q

What are the product(s) of cleavage of an immunoglobulin by pepsin?

A

Dimeric antigen-binding molecule

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3
Q

What are the product(s) of cleavage by papain?

A

Two separated antigen-binding fragments

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4
Q

What cells express MHC II?

A

B cells, dendritic cells, and macrophages

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5
Q

What is the basic structure of a T cell receptor?

A

Membrane bound alpha/beta or gamma/delta heterodimer

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6
Q

What is the migration of B lymphocytes to specific sites (like lymph nodes) dependent on?

A

Selectins

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7
Q

What is the role of STAT after cytokine binding to a specific cell surface receptor stimulating a lymphocyte to undergo signaling?

A

The STAT dimers induce translocation to the nucleus to regulate transcription

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8
Q

What type of cells have somatic hyper mutations? Does this process happen before or after antigen exposure?

A

B cells to increase binding affinity for epitope

After (all other processes that result in gene rearrangement aka junctional diversity and VDJ rearrange happen before)

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9
Q

What is allelic exclusion?

A

Heavy and light chains contain both maternal and paternal derived chains however, the cell only EXPRESSES one of the chains

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10
Q

What happens if an early thymocyte doesn’t have IL-7 receptors?

A

Apoptotic death

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11
Q

Where are gamma delta T cells normally found?

A

In the respiratory or organs, skin, and peritoneal cavity

React more rapidly than alpha beta T cells

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12
Q

What kind of receptors do NKT cells express?

A

TCRs generated by DNA rearrangment and junctional diversity

They can be either CD4+ or CD4+CD8+

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13
Q

What do pre-B-cells express?

A

Igalpha and Igbeta BCR accessory models

No surrogate light chain until pro-b

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14
Q

What is the function of B1 cells?

A

Innate related immune responses

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15
Q

What naive cells loads peptide fragments into MHC class II molecules?

A

dendritic cells:

  • alpha beta complexed with invariant chain synthesized in ER
  • at same time extracellular proteins taken up into APCs and processed in lysome/endosome
  • fusion of vesicle with alpha beta with lysosome with degraded proteins
  • lysosomal enzymes degrade invariant chain and replace with CLIP
  • HLA DM exchanges CLIP and express MHC II on surface
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16
Q

How are fragments of a cytoplasmic pathogen presented to Cells?

A

MHC class I molecules present to CD8+ T cells who destroy the infected cell

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17
Q

What are Th1 cells?

A

CD4+ T cells that respond to INTRACELLULAR pathogens by recruiting and activating phagocytic cells specifically macrophages

PRODUCE IFN-gamma!!! activates macrophages
Receptor part of type II cytokine receptors

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18
Q

What does Th2 cells produce?

A

IL-4 (most important) as well as IL-5 (eosinophil activation, allergies) and IL-10

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19
Q

What signaling molecule does CD4/CD8 coreceptor in T cells use to activate PLC cascade?

A

Lck which phosphorylates ITAM

activation of protein tyrosine kinase leading to signaling cascade

20
Q

What signaling molecule does CR2 coreceptor in B cells use to activate PLC cascade?

A

Syk (PI3 kinase) activated via signaling of Igalpha and Igbeta cytoplasmic tails of BCR after cross-linking of 2 or more BCRs

21
Q

What are the initial cellular events that happen after there is antigen mediated cross linking of the BCR complex

A

Increased expression of IL-2 receptor causing enhanced proliferation (more time in mitosis) in response to T cell signals and increased Bcl-2 for survival

Increased expression of B7 causing enhanced APC function

Increased CCR7 so cells can migrate out of lymph nodes towards the T cell zone

22
Q

What is the antigen recognition event that occurs in a lymph node during T-helper-dependent antibody response to antigen?

A

Naive B cells recognize intact proteins, generate peptide fragments of these proteins and present them in complexes with MHC molecules to differentiated helper T cells

23
Q

What B cell responses are stimulated by CD40 ligand?

A

Association of TRAFs with cytoplasmic tails of CD40 molecules
Activation of NF-kB
Enhanced expression of B7
Enhanced Ig isotype switch with recombinase activity
NOT enhanced production of membrane Ig

24
Q

What mechanism allows B cell to change from producing to secreting Ig?

A

Alternative processing of primary RNA transcripts to remove the transmembrane domain and include a secretory tail piece
Differential splicing

25
Q

What does affinity maturation depend on?

A

Somatic mutations of V genes –> basis of Igs with different affinities

26
Q

What can activate B cell antibody production without aid of T cells?

A

Polysaccharides (ex. ABO blood group antigen)
Glycolipids
Nucleic acids with multiple repeated epitopes

27
Q

What causes Toxic Shock Syndrome?

A

Excessive activation of CD4+ T cells (binds MHCII because bacteria)

28
Q

What germinal center reactions occur during antigen-dependent development of B cells?

A 
Clonal expansion, class switching, somatic hyper mutation and differentiation 
Allelic exclusion is antigen INDEPENDENT
29
Q

How is receptor mediated and extrinsic (cyto) apoptosis different?

A

Receptor mediated require susceptibility by the target cell

Extrinsic/granule mediated can target any cell

30
Q

What is the seqeunce of events that causes cross presentation in dendritic cells?

A 
Antigen/microbe/cell is phagocytosed and broken down in lysosomes
Antigens transported to cytosol for proteosomal degradation and transported to ER where they are loaded onto MHC class I and transported to the surface
31
Q

What does CTLA-4 compete with? What does CTLA-4 binding cause?

A

Competes with CD28 for binding to B7 on B cells

32
Q

What cell type(s) express high-affinity trimer IL-2R(alpha beta gamma chains)

A

Only activated T cells CD4+ and CD8+

33
Q

What happens when cytoplasmic signals are generated in response to antigen binding and co stim signals in CD 8+ cells?

A

Activation of TFs that up-regulate IL-2
Aggregation of TCR and CD8
Increased free intracellular Ca++
TK binding to cytoplasmic domains of CD3 and CD8 –> signaling

34
Q

How can a single B cell express IgM and IgD molecules on its surface at the same time?

A

Through alternative RNA splicing

35
Q

What is expressed on the surface of mature B lymphocytes?

A

CD40
MHC class II molecules
CD19
IgM and IgD

36
Q

Where does the synthesis of antibodies occur?

A

In secondary lymph organs

37
Q

What does the cytoplasmic region of surface IgM consist of?

A

3 amino acids

38
Q

What expression pattern does MHC genes have?

A

Codominant, both maternal and paternal expressed

39
Q

What molecules mediate signal transduction following antigen binding to cell surface Ig on B cell

A

Ig-alpha and Ig-beta

B cells are only cell with surface Ig

40
Q

What molecules mediate signal transduction following antigen binding to cell surface Ig on T cell

A

CD3

TCR= heterodimer

41
Q

What is CD28?

A

Ligand found on T cells which binds to B7 (CD80) on professional APCs
Main costimulatory signal for activation of resting T-cells

42
Q

How do IFN-gamma and TNF-alpha act synergistically?

A

Upregulate expression of MHC class II

43
Q

What cells express CD40 what cells express CD40L?

A 
CD40= dendritic and B cells
CD40L= T-cells
44
Q

Which isotype of antibody should be used in designing a monoclonal antibody against an extracellular pathogen?

A

IgG is the isotype with the greatest amount of humoral protective functions. It participates in opsonization, neutralization, complement fixation and can cross the
placenta

45
Q

What does double-stranded RNA-dependent protein kinase mediate?

A

Type I interferons: it is a serine/threonine kinase, is a component of host responses to infection and various situations of cellular stress. PKR is a key mediator of interferon (IFN) action, the first line of defense against viral infection

SFM Final Lectures (7 decks)

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