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IMIN 371 > Immune memory and vaccines > Flashcards

Immune memory and vaccines Flashcards

1
Q

What is the hallmark of acquired immunity?

A

development of memory response

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2
Q

Describe the memory B cell response in comparison to the primary response

A
  • long lived
  • respond more quickly to subsequent infection
  • high Ab titires
  • makes Abs of high affinity and have class switched
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3
Q

Why do memory B cells respond more quickly to Ag?

A
  1. higher frequency of Ag-specific B cells
  2. express higher levels of MHC-II and T cell costimulatory molecules
    - can get better help from T cells
    - don’t require as much T cell help
  3. memory T cells to same Ag
    - larger numbers of T cells to help B cells
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4
Q

Describe some charactersistics of long-lived plasma cells: what type of cell they resemble, where they are found, source, lifespan, Ab properties

A
  • resemble “memory” cells
  • found = some in bone marrow, most in gut and lung mucosa
  • source = primary focus and germinal centre
  • lifespan = long lived (e.g. the persistence of serum Ab.s to smallpox vaccine 75 years later)
  • Ab properties = do not need Ag stimulation to produce Ag-specific Abs
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5
Q

Describe the relationship bewteen self renewal + memory potential and differentiation status of memory T cells and Ag exposure

A

low Ag exposure: high ability to self-renew + memory potential, lowly differentiated

high Ag exposure: low ability to self-renew + memory potential. highly differentiated

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6
Q

Describe the differentiation order from low to high Ag exposure of memory T cells

A

naive T cell –> Tscm –> Tcm –> Tem –> Teff –> death, note: Tcm, Tem, Teff can differentiate into Trm (sits between Tem and Teff)

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7
Q

What are some characterisitics of Tscm cells?

A
  • scm = stem cell memory
  • found in secondary lymphoid tissue
  • can develop into all other memory subsets
  • self renewing
  • long lasting source of T cells
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8
Q

What are some characterisitics of Tcm cells?

A
  • central memory
  • can go back into secondary lymphoid organs unlike other activated T cells
  • travel between secondary lymphoid organs
  • long lived and slowly proliferate
  • rapid activation
  • produce lots of IL-2
  • can differentiate to various effector T cells
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9
Q

What are some characterisitics of Tem cells?

A
  • em = effector mememory
  • patrol tertiary sites
  • proliferate very little if at all
  • rapid effector response
  • produce little IL-2
  • commited to a specific effector lineage
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10
Q

What are some characterisitics of Teff cells?

A
  • eff = effector
  • e.g. CTL, Th
  • do not go back into secondary lymphoid tissue
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11
Q

What are some characterisitics of Trm cells?

A
  • rm = resident memory
  • upregulate tissue markers –> forces rm to stay in that tissue
  • permanent residents of previously infected tissues
  • extremely rapid and localized effector response
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12
Q

What are some surface markers found on various memory T cells and what is their role? What memory T cells have which?

A
  • CCR7 = chemokine R, homing to secondary lymphoid organs (naive, scm, cm)
  • CD62L = L-selectin. adhesion protein, homing to secondary lymphoid organs (naive, scm, cm)
  • CD44 = cell surface glycoprotein involved in cell adhesion, highly expressed when TCR is activated (cm, eff, em, rm)
  • CD69 = C-type lectin, prevent immune cells from leaving tissues (rm)
  • FAS = R for FASL (all activated T cells, not naive)
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13
Q

Describe T cell homeostasis between naive, effector and memory T cells

A

naive
- live months to years
- undergo minimal basal proliferaiton
- rely on IL-7 to maintain

effector:
- live days to weeks
- derived from both naive and memory T cells
- terminally differntiated and part of large clonal populations

memory:
- live months to years
- undergo extensive basal proliferation
- rely on IL-7 and 15

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14
Q

What is passive immunization, when is it needed, what are some side effects?

A

passive immunization = delivery of preformed Ab

conditions where this is needed:
- immune deficiency
- toxin or venom exposre with immediate threat to life
- exposure to pathogens that can cause death faster than an effective immune response can develop

side effect = can lead to type I or II hypersensitivities

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15
Q

What is active immunization?

A

immunization to induce immunity and memory

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16
Q

Why is the HPV vaccine important? What is the HPV vaccine?

A
  • HPV implicated in 99% of cervical cancers
  • high risk HPV (16 and 18) make up 70% of all cancers
  • vaccine = Garadasil
17
Q

What are the pros and cons of whole organism, live attenuated vaccines? Name some examples

A

pros:
- retain their ability to replicate, promoting strong humoral and cell-mediated responses
- often do not need boosters

cons:
- may revert to pathogenic form
- may have more side-effect complications
- may also require refrigeration for stability during transport

examples:
- polio, measles, mumps, rubella, TB

18
Q

What are the pros and cons of whole organism. inactivated/killed vaccines?

A

pros:
- no reversion
- often more stable/easy to store and transport

cons:
- often require booster shots
- don’t replicate in host –> don’t induce cell mediated immunity, humoral only
- manufacturing risks to personnel
- adjuvants often required

19
Q

What are adjuvants and how do they work?

A
  • adjuvant = enhance the immune response to a vaccine especially if the Ag is a weak simulator
  • promotes inflammation to recruit more immune cells to the area, enhancing effectiveness
  • slows down Ag release to promote longer interactions, enhancing effectiveness
20
Q

Name and describe three common adjuvants

A
  1. alum
    - good at stimulating Th2, but not Th1 responses
  2. MF39
    - oil in water emulsion, slows Ag delivery
  3. AS04
    - alum + TLR4 agonist, encourages Th1 response
21
Q

Describe the types, pros and cons, and name examples of purified macromolecules subunit vaccines

A

types:
- inactivated exotoxins/toxins
- inactivated capsular polysaccharides
- inactivated surface glycoproteins

pros/cons:
- similar to those of inactivated vaccines

examples: DTaP, HBV

22
Q

Describe what purified macromolecule conjugate vaccines are/why they’re used, examples, and how we can induce CTL responses with these?

A

why they’re used:
- conjugate or multivalent vaccines can improve immogenicity and outcomes
- some Ag are not strong enough on their own to stimulate a good response, so they are coupled to something else that is particularly good at Ab induction

example: influenza B, pneumonia

what about CTL responses:
- simple linking of a weak Ag with a stronger one may not give the desired outcome –> Ag has to be delivered into cells for presentation on MHC-I molecules
- creation of lipid carriers known as ISCOMs for delivery into cells

23
Q

Describe what recombinant vector vaccines are, the pros and cons, and examples

A

what they are:
- use a different attenuated pathogen and genetically engineer it to carry and express another pathogen’s genes

pros:
- all the benefits of attenuated vaccines
- fewer risks - not using the actual pathogen, but something else entirely

cons:
- some of the attenuated vaccine problems present (esp stability issues)

example: vaccina, ebola

24
Q

Describe nucleic acid based vaccines: how they work, pros and cons, examples

A

how they work:
- DNA and mRNA encoding pathogen sequences are packaged and injected into muscle tissue
- host cells take up DNA or mRNA and express it internally
- makes protein to gen Ab response
- provides Ag for presentation via MHC-I, stimulating CTL production

pros:
- induces humoral and cell-mediated immunity
- prolongs expression, should enhance memory
- very stable and customizable

cons:
- TBD

examples: SARS-CoV 2

25
Q

What are two reasons why we should be vaccinated?

A
  1. herd immunity
    - fewer number of individuals who can spread an infection
    - protects susceptible indiviudals –> young childre, immunocomprimised, those who have an ineffective response to vaccine
  2. protection against the infection but also against complications for that infection
26
Q

What is the Ro?

A
  • reproduction rate
  • measures how infectious a pathogen is
27
Q

What is the herd immunity threshold (HIT)?

A

percentage of population that must be immune to stop the spread of the pathogen

IMIN 371 (20 decks)

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