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IMMUNOLOGY > LECTURE 4 (Innate immune system) > Flashcards

LECTURE 4 (Innate immune system) Flashcards

1
Q

What is the function of the Innate Immune System?

A

It is responsible for reacting quickly to invading microbes and for keeping the host alive while the adaptive immune system is developing a very specific response

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2
Q

Are innate immune defences present at birth? (YES/NO)

A

YES

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3
Q

What are the characteristics of the Innate Immune System?

A
  • Very limited diversity for antigen (Primitive and broad)
  • Attack all microbes the same way no matter how many times they have seen the same pathogen (Unspecific)
  • Immediate
  • Fast
  • No memory
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4
Q

What are the two ways that the innate immune system handles pathogens?

A
  • Inflammation -> Elimination of microbes
  • Interferons & Natural killer cells -> Elimination of viruses
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5
Q

What are the different Cytokines?

A
  • Chemokines
  • Interleukins
  • Tumour Necrosis Factor
  • Interferons
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6
Q

What happens when physical barriers are breached?

A

Microbes may gain access to the tissues where they come in contact with PHAGOCYTIC CELLS (neutrophils, macrophages and dendritic cells) which produce CYTOKINES (chemical messengers) -> Initiates an INFLAMMATORY RESPONSE

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7
Q

What can happen once pathogens gain access to the blood?

A

The adaptive immune system may have to take over to resolve the infection and eliminate the pathogen

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8
Q

What are considered “early defence against pathogens”

A
  • Physical (anatomic) barriers
  • Physiologic barriers
  • Innate cellular response
  • Inflammation
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9
Q

What are the main portals of entry for most pathogens?

A
  • Skin
  • Respiratory tract
  • GI tract
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10
Q

What are the properties of the surfaces that pathogens can enter into?

A
  • Lined with epithelial cells that can produce DEFENSINS and INTERFERONS (antimicrobial products)
  • Contain specialised intra-epithelial lymphocytes (IEL) called γδ T cells
    [considered part of innate immunity as they only recognise shared microbial structures]
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11
Q

How do Tears aid Innate immunity?

A
  • Wash away irritating substances and microbes
  • Lysozyme kills many bacteria
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12
Q

How does skin aid Innate immunity?

A
  • Provides a physical barrier to the entrance of microbes
  • Acidic pH discourages growth of organisms
  • Sweat, oil and fatty acid secretions kill many bacteria
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13
Q

How does the Respiratory tract aid Innate immunity?

A
  • Mucus traps organisms
  • Cilia sweep away trapped organisms
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14
Q

How does the GI tract aid Innate immunity?

A
  • Large intestine has normal bacterial inhabitants that keep invaders in check
  • Stomach acid kills organisms
  • Saliva washes microbes from teeth and mucous membranes of mouth
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15
Q

How does the Bladder aid Innate immunity?

A

Urine washes microbes from urethra

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16
Q

What are the different Physiological barriers?

A
  • Temperature
    [when inflammatory response is initiated in the local tissues -> cytokines acts systemically to alter temp set point in hypothalamus resulting in fever]
  • pH
17
Q

What are the different Chemical barriers?

A
  • Lysozyme (present in tears, saliva, breast milk and mucous) can break down the CELL WALL PEPTIDOGLYCAN of bacteria
  • DEFENSINS found within phagocytes can form PORES in bacteria and fungi
  • IFN-α and IFN-β are ANTI-VIRAL INTERFERONS -> direct anti-viral effect by inhibiting NASCENT PROTEIN SYNTHESIS in cells
18
Q

How do Phagocytic cells recognise pathogens?

A

via shared molecules that are not expressed on host cells

  • PATHOGEN-ASSOCIATED MOLECULAR PATTERNS (PAMPs) = molecules shared by pathogens of the same type
  • DAMAGE-ASSOCIATED MOLECULAR PATTERNS (DAMPs) = released from dying or damaged cells
19
Q

What are Pattern Recognition Receptors (PRRs)?

A

Receptors of the innate immune system

20
Q

What are the properties of Pattern Recognition Receptors (PRRs)?

A
  • Present intrinsically
  • Encoded in the germline genes
  • Not generated through somatic recombination in the same way lymphocyte receptors are generated
21
Q

What is the Inflammasome?

A
  • Expressed in myeloid cells as a SIGNALLING SYSTEM for detection of pathogens and stressors
  • Activation results in production of IL-1b and IL-18 (potent inflammatory cytokines)
22
Q

What does a mutation in signalling molecules effecting TLRs lead to?

A

Recurrent, severe bacterial infections (pneumonia)

23
Q

What do Gain of function mutations in inflammasome lead to?

A
  • Gout
  • Atherosclerosis
  • Type II diabetes
24
Q

What do NOD-2 mutations result in?

A

IBD (Inflammatory Bowel Disease)

25
Q

What do IL-12 and IFN-γ receptor deficiencies result in?

A

Recurrent infections with intracellular bacteria (Mycobacterium)

26
Q
A

IMMUNOLOGY (6 decks)

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