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Flashcards in Host Defense Deck (22):
1

Innate vs. Adaptive Immunity

Innate vs. Adaptive Immunity

Innate immunity

  • fast response
  • not as selective
  • always working
  • no memory

Adaptive immunity

  • slower response
  • very specific
  • needs to be activates
  • memory

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2

Innate immunity: overview of features

Innate immunity: overview of features

  • constitutional factors
  • natural barriers and flora
  • cytocines/interferons
  • phagocytosis
  • complement 

3

Innate immunity: constitutional factors

Innate immunity: constitutional factors

factors that make one species succeptable and another resistant to certain infections. 

  • genetics- species differences
  • age
  • metabolic factors
  • neuroendocrine factors
  • environment- resource availability, population dynamics

4

Innate immunity: natural barriers & flora

Innate immunity: natural barriers & flora

Natural barriers= literally just shit thats there naturally that prevents shit.  

  • mechanical barrier: physical structure/aspect that prevents disease
    • ex. epidermis/dermis of skin
  • chemical barrier: chemical interactions that prevent disease
    • ex. high salt, organic acids, and defensins present in skin

Normal flora= some microbiota prevent colonization by others

 

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5

Innate immunity: cytokines/interferons

Innate immunity: cytokines/interferons

Cytokines- glycoproteins that are released to tell body to initiate immune response

Interferons- special cytokines related to viral infections

  • Type I interferons- role in viral immune defense
    • IFN System- crucial for viral defense... discussed how mice with different aspects of IFN inhibited showed reduced immune ability 

6

Innate immunity: phagocytosis

 

Innate immunity: phagocytosis

phagocytosis= engulfment & digestion of infectious agents 

  • two cell types
    • macrophage
    • neutrophil
    • eosinophils (rare)
  • see steps below...
    • ingested bacterium= phagosome
    • fused with lysosome= phagolysosome
    • lysosome= enzymes digest captured bacteria
      • know what cells to digest using pattern recognition receptors (PRR)
      • PRRs recognize pathogen-associated molecular patterns (PAMP) on pathogens

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7

Neutrophils and macrophages ?

Phagocytic cells in innate immune response

Macrophage: 

  • several receptors specific for bacterial constituents (PRR)
  • when bacteria bind receptor and PAMP is recognized, macrophage engulfs and digests it. 

Neutrophils: primarily target extracellular bacteria and fungi

  • express receptors for many bacteria and fingi (PRR)
  • when bound by pathogen (PAMP), engulf and destroy with toxic constituents of neutrophil granules
  • *** note, encapsulated bacteria connot be bound by neutrophils. antibodies bind to these bacteria, permitting binding to neutrophil and facilitating engulfment

8

Natural Killer Cells

Innate immunity: Natural Killer Cells

NK Cells- 

  • Structure: large granular lymphocytes
    • no antigen-specific receptors
  • Increse rapidly after viral infection
  • Recognize "self-altered" cells (INF)
    • has two receptor binding technique
      • one receptor activates nk if cell is infected
      • one receptor blocks nk if cell is not
  • kills cells by releasing perforins and granzymes (cytokines)
    • perforate membranes and trigger caspase
  • MHC I

9

Innate immunity: complement

Innate Immunity: compliment pathways

  • 1. classical pathway
  • 2. alternative pathway
  • 3. lectin
  • all end in terminal pathway, but activation factors are different

See video from lecture for clarification (host II)

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10

classical pathway

Innate immunity: classical pathway

Activatior: C1 binds to reactive protein or binding of antibody to antigen

Initial complement: activates the classical pathway, in which it breaks c4 into multiple parts (c4a=small c4b= big).

C3 convertase- C4bC2b

C5 convertase- C4bC2bC3b

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11

lectin pathway

Innate immunity: lectin pathway

activator- mannan binding lectin (MBL), MBL-associated serine protease-2 (MASP-2)

Initial complement component- C4, C2

C3 convertase- C4bC2b

C5 convertase- C4bC2bC3b

 

12

Alternative pathway

Innate immunity: alternative pathway

activator- contact of microbial cell wall with C3

Initial complement component- C3, Factor B, Factor D, & properdin

C3 convertase- C3bBb

C5 convertase- C3bBbC3b

 

13

Results of compliment activation

Results of compliment activation

  • clearance of immune complexes
  • cell lysis
  • bioactive substances
  • removal of particulate antigens

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14

Adaptive immunity: Humoral immunity

Adaptive immunity: Humoral immunity

= mediated by antibodies secreted by antigen-activated B cells and their progeny plasma cells

  • Primary
  • Secondary

15

Adaptive immunity: primary and secondary 

 

Adaptive immunity: Humoral immunity

Primary vs. Secondary immune response

  • primary response
    • more time
    • weaker response
    • utilizes IgM
  • secondary response
    • shorter lag phase
    • greater magnitude
    • class-switched IgG (IG=immunoglobin)

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16

Adaptive immunity: Cell Mediated Response

Adaptive immunity: Cell Mediated Response

  • mediated by antigen-activated T-cells 
    • CD8 T cells function as cytotoxic T cells (CTL)
    • CD4 T cells and activated Macrophages function in DTH responses (delayed type hypersensitivity) Helper T cells

17

MHC

MHC= Major histocompatibility complex

part of adaptive immunity

2 classes of proteins- T-cells require MHC presentation

  • MHC class I- destroy extracellular pathogens
    • Location: nucleated cells
    • function: present Ag to cytotoxic t cells
    • result: t-cell mediated toxicity
  • MHC class II-destroy intracellular pathogens
    • location: b cells, macrophage and dendritic cells
    • function: present Ag to T helper cells
    • result: t-cell mediated help

Note: mhc restriction restricts immune response!

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18

APCs

APCs= Antigen presenting cells

  • macrophages, dendritic cells and be cells
  • must be MHC-II positive
  • ... SOOOO MUCH STUFF MISSED IN PPT 3.  FIGURE IT OUT LOSER!!!

 

19

ADCC

Antibody Dependent Cell-mediated Cytotoxicity

=cell-mediated immune defense

  • effector cell lyses target cells with membrane surface antigens that can be bound by specific antibodies.  
  • ex. NK cells, Macrophages, Neutrophils, eosinophils

NEED : NK cell, antibodies, and antigen

 

20

Neutrophils

Neutrophils

  • Function: phagocytosis
  • super effective in extracellular bacterial infections
  • involved in acute inflammation
  • live only 24 hours
  • Stored in bonemarrow

21

Eosinophils

Super effective in parsite infections (helminths)

22

PRR and PAMP

Pathogens have PAMPs- "pathogen associated molecular patterns"

Immune cells have PRRs- "pathogen recognition receptors"

 

 

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