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Flashcards in Extra Stuff for Competition Deck (28):
1

Describe the morphology + function of NK cells.

  • large, granular lymphocytes without BCR/TCRs
  • recognize virus-infected/tumor cells via MHC-I or Ab tagging
  • action regulated by balance of activating (ex: NKG2D) or inhibiting (ex: NKG2A) receptors
  • provide rapid response (~3 days) to viral infection

2

Decribe the features / function / abilities of gamma delta T cells

  • have distinct TCR of gamma + delta chains
  • can rearrage TCR for specificity or use more conserved TCR that recognizes PAMPs
  • Functions:
    • lyse stressed cells
    • produce cytokines
    • help B cells
    • present antigens to alpha-beta T cells
    • help dendritic cells mature
    • regulate stromal cells using GFs

3

What are innate lymphoid cells?

  • come from lymphoid precursor cells but lack rearranged TCR/BCR
  • lack mature lymphoid markers but have lymphoid progenitor receptors
  • have high capacity / diversity cytokine production
  • regulate homeostasis in mucosa, skin, fat + lymphatics
  • are self-renewing + don't give rise to progenitors

4

What are 5 kinds of secreted PRRs?

  • Soluble Lectins (includes MBL, surfactant + pentraxins such as CRP)
  • Lipocalin / Mindin
  • Cationic Peptides
  • Antimicrobial Peptides
  • Cathelicidins

5

what do NOD-like receptors do within cells?

are released into cytosol to recognize intracellular bacterial peptidoglycan

6

What do RIG-I-like receptors do within cells?

recognize viruses via dsRNA

7

What is somatic hypermutation?

  • an increased rate of mutation seen in proliferating B cells
  • occurs in "hotspots" in DNA hypervariable regions corresponding to CDRs on BCRs / antibodies
  • occurs via cytidine deamination to uracil via AID and removal of uracil bases by UDG

8

Describe MHC-I structure.

  • alpha 1 + 2 subunits make up peptide binding groove
  • alpha 3 subunit has TM domain -> anchors to membrane
    • (alpha3 is also binding site for CD8 on CTLs)
  • beta-2 microglobulin associates with alpha sub-units (but does not bind membrane)

9

Describe MHC-II structure

  • alpha1 and beta1 subunits make up peptide binding groove
  • alpha 2 and beta2 both have TM domains -> anchor to membrane
  • beta2 subunit is CD4 binding site

10

There was a horribly worded PP question that said

"List at least 4 features of cell ines"

based on the corrected answers I think they meant cancer cells...

  1. Transformation - different morphology
  2. Loss of "contact inhibition"
  3. Lack of need for GFs to proliferate
  4. Immortality
  5. Regaining of telomerase activity

11

What is important to note about the lineage of all the B cells in a single lymph node follicle?

  • each follicle has one "founder" cell of which all other B cells in that follicle are descendents

12

What is unique about follicular dendritic cells?

What surface molecules do they express in order to carry out their functions?

  • they do not leave follicles and can not engulf pathogens
  • instead, they just hold onto antigens + express IL-6 for the activation of follicular Th cells
  • express FcRs and CR3 (complement receptor) to bind antibodies and C3b, allowing them to tightly hold antigens

13

What are 4 functional results of Th cells stimulating B cells using their CD40L.

(CD40L on T cell stimulates CD40 on B cell)

  • generation of germinal centers -> proliferation -> Ab production
  • affinity maturation
  • isotype switching
  • memory cell generation

14

What two types of mutations can occur during somatic hypermutation?

  • Transition Mutation - deaminated cytosine changes to uracil via AID enzyme and is then cut off and replaced with a different base
  • Transversion - uracil is removed by UNG enzyme and an "apyrimidinic" residue results (means there is no base there... just blank space)

15

What are the Th-secreted cytokines which induce IgM to...

IgG class switch?

IgA class switch?

IgE class switch?

(other lectures had longer lists of cytokines for each class... B cell lecture had the simplest list)

  • IgE - IFNy
  • IgA - IL-5
  • IgE - IL-4 and IL-13

16

What role does a somatic hypermutation enzyme have in class switching?

  • AID (activation induced deaminase) - deaminates C to U
  • DNA breaks are created at site of the Us which are in so-called "switch regions"
  • repair of these breaks leads to recominbation + creation of a different switch region

17

What receptor on B cells produces a negative feedback inhibition?

  • FcyRIIb - binds IgG that has already bound pathogens
  • other epitopes on the antigen may simultaneously bind the same B cell's BCR, but since the B cell can "detect" that IgG is already there -> inhibition + less production of IgG 

18

Where do memory B cells reside?

  • mantle zone of lymph follicle (outer ring surrounding germinal center)

19

What are some characteristics of memory B cells?

  • have undergone class switch / affinity maturation
  • can produce high affinity Abs IgG/A/E
  • high affinity Th interactions + rapid plasma cell diff.
  • higher capacity Ab production

20

What Fc receptor is responsible for the ADCC effects of antibodies?

  • FcyRIIIA - on NK cells, binds IgG -> cellular cytotoxicity effects 

21

What are MZ B cells?

  • a B-2 cell type in the marginal zone of the spleen
  • recognize T-independent sugar antigens, such as capsular polysaccharides
  • secrete mainly IgM (with a somatically mutated sequence)

22

What are 5 general mechanisms of peripheral T cell tolerance?

Potentially auto-reactive T cells may tolerate self antigens due to...

  1. Ignorance - via physical barrier such as BBB
  2. Immune-privelege - cornea produces FasL, TGF-B + IL-10
  3. Apoptosis
  4. Anergy - absence of positive co-stim
  5. Becoming tolerogenic
  6. Suppression - by a Treg etc.

23

What region of the BCR genes is most likely to be autoreactive?

the V region of the VDJ genes

24

What do receptor revision and receptor editing happen in B cells to avoid auto-reactivity?

  • Revision - in 2ndary lymph organ germinal centers
  • Editing - in bone marrow in early development
  • both via RAG recombinase reactivation

25

What kind of cell is common in "natural autoimmunity"?

  • CD5+ B1 cell
  • is polyreactive to essential/conserved molecules common to both humans and microbes
  • secretes mostly low-affinity IgM

26

What kind of conserved molecules do we create "natural autoantibodies" against?

long list... just a review

  • HSPs
  • enzymes
  • membrane proteins -beta 2 microglobulin
  • cytoplasmic proteins - actin
  • nuclear antigens - histones
  • plasma proteins - albumin, IgG
  • cytokines - IL-1

27

How can infections contribute to the development of autoimmunity?

  • secretion of inflammatory mediators
  • increased costimulation
  • release of tissue antigens (via damage)
  • molecular mimicry - host/pathogen cross-rxn
  • superantigens

28

What cytokine can DCs secrete in autoimmunity that inhibits Treg's suppressive functions?

IL-6