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Parasitology > Week 3: Immunobiology > Flashcards

Week 3: Immunobiology Flashcards

1
Q

Commonalities between plant, invertebrate, and human (vertebrates) immune systems

A
  • all use body surface as first line of defence
  • once inside, hosts rely on innate immunity
  • can differentiate between self and non-self molecules
  • reliance on PRRs (pattern recognition receptors) to recognize signals of infection
  • involve MAMPS
  • involved DAMPS
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2
Q

Characteristics of plant immune systems

A
  • have physical barriers: outer part of leaves, layers of wax, stomata
  • no specialized immune cells, every cell is an immune cell, protect themselves
    2 levels of protection:
    1. Extracellular pattern recognition receptors (PTI: pattern triggered immunity)
    2. Intracellular receptors (ETI: effector triggered immunity)
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3
Q

Extracellular pattern recognition receptors and pattern triggered immunity (PTI)

A
  • pattern recognition receptors on surface of cell recognize common parts of pathogens, usually recognize part of bacterial flagella
  • they bind to the microbe-associated molecular pattern (MAMP), is the conserved molecular pattern from the pathogen
  • signals to plant cell that there is a bacteria outside
  • starts immunity inside plant cell
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4
Q

Intracellular receptors and effector triggered immunity

A
  • some pathogens inject proteins into host cell, called effector molecules
  • they can turn off the immune system
  • have receptors inside the cell that recognize the effectors, R-proteins
  • bind to the effectors which turns on immunity
  • has a greater level of immune expression because it deals with pathogens inside the cell
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5
Q

Defense responses of plants

A
  • direct killing of pathogen via reactive oxygen species and other molecules
  • reinforcement of cell wall for physical protection (callose and lignin)
  • systemic signalling: close stomata and warn rest of plant
  • programmed cell death to limit spread
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6
Q

Innate immunity

A
  • non-specific
  • pre-formed: always there ready to use
  • usually occurs rapidly following infection
  • recognizes a few highly conserved structures, rather than specific antigens
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7
Q

Types of innate immunity in plants

A
  • physical barriers
  • mechanical removal
  • defense chemicals
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8
Q

types of innate immunity in inverterbates

A
  • physical barriers
  • mechanical removal
  • defense chemicals
  • complement pathways
  • phagocytosis
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9
Q

things unique to innate immunity in invertebrates

A
  • have specialized immune cells that contain PRRs
  • MAMPs can also be recognized by soluble PRRs in the blood, initiates complement pathways
  • complement pathways and phagocytosis
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10
Q

complement systems in invertebrates

A
  • soluble proteins that float around in the hemolymph
  • has 3 roles:
    1. direct lysis
    2. opsonization
    3. melanization
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11
Q

direct lysis

A

forming a pore in the pathogen, breaking it open and killing it

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12
Q

opsonization

A
  • coats an invader with complement proteins or antibodies
  • makes it easier for immune cells to recognize and makes it a target for phagocystosis
  • can also coat it to stop it from doing things
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13
Q

melanization

A

melanin deposits around pathogens that are to big too eat, which makes them harmless

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14
Q

things unique to human innate immunity

A
  • have complex immune cells
  • inflammation and fever as innate immunity
  • complement pathways and phagocytosis
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15
Q

things involved in human innate immunity

A
  • mechanical barriers: skin, acidic pH in stomach
  • humoral (mediated by macromolecules) mechanisms: lysozymes, complement, interferons
  • cellular defense: kill, eat things, help adaptive immune system
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16
Q

adaptive immunity

A
  • only in vertebrates
  • recognition of specific antigens
  • gets better at recognizing things that commonly infect you
  • genome of immune cells change over time to make better antibodies
  • has anamnestic memory
  • leads to clonal expansion
17
Q

anamnestic memory

A

repeated exposure to pathogen leads to faster, and stronger immune response

18
Q

clonal expansion

A

single immune cell that recognizes the right antigen is selected for and makes lots of copies of itself

19
Q

lymphocytes

A
  • have receptors on surface that recognize a specific antigen
  • when they bind, they become activated, replicate and either build immunological memory or kill things and make anitbodies
    2 types:
    1. T cells: regulate other immune cells and kill cells
    2. B cells: produce antibodies
20
Q

generalized immune response

A

often begins as TH1 to limit initial spread, then switches to TH2 during chronic infection

21
Q

TH1 response

A
  • responds to intracellular pathogens
  • produces cytokines that cause inflammation and recruit macrophages
  • macrophages kill intracellular pathogens
  • produces antibodies that mark infected cells for opsonization
  • causes strong inflammation and damage to host tissue
22
Q

immunopathology

A

focuses on how the immune response, which normally protects the body from infections and diseases, can sometimes contribute to or cause tissue damage, inflammation, or other health problems.

23
Q

TH2 response

A
  • responds to extracellular pathogens
  • produces cytokine that stimulates B-cells to grow and secrete lots of antibodies
  • also stimulates mast cells and eosinophils
  • tends to clear worm infections
  • leads to inflammation but less than TH1
  • inappropriate use can lead to allergies
24
Q

Phases of response

A

Primary:
- activation of specific clonal T effector cells and production of memory populations
- develops over several days
- not as effective at protection or limiting infection
Secondary:
- activation of memory cells
- more pronounced and faster because it has whole population of clonal memory cells
- effective at limiting infection

25
Q

Humoral Immune Response

A
  • B lymphocytes recognize specific antigens and make anitbodies
  • antibodies bind to antigens
    -they work with complement pathway
  • perform opsonization
  • perform sequestration: coat pathogen in antibodies so it can’t interact with your cells
  • some B lymphocytes differentiate into memory cells
26
Q

Cell mediated immunity vs humoral immunity

A

Cell mediated
- T cells
- TH1 and TH2
Humoral
- B cells
- production of antibodies
- less inflammation

27
Q

Parasite strategies to evade immune system

A
  1. Intracellular: live inside host cells because no antibodies inside the cell
  2. Antigenic variation: change coat once immune system creates antibodies to fight the previous one
  3. Dormancy: form cyst and becomes metabolically inactive until next host, immune system ignores things that aren’t active
  4. Host mimicry: produce molecules that mimic host proteins
  5. Immune modulation: manipulate host immune response through false info, force inappropriate timing of TH2 switch and inhibit TH2 switching
  6. Immune destruction: destroy host immune response, cleavage of complement proteins and antibodies

Parasitology (12 decks)

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