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POM Y1 Imperial > Immune response > Flashcards

Immune response Flashcards

1
Q

What is the innate immune system?

A

Refers to non-specific defense mechanisms that activate within initial exposure to an antigen; includes germline-encoded receptors - unchangeable genome binds to particular ligands

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2
Q

What are the physical barriers of immunity?

A

Skin, mucous, epithelial cells

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3
Q

Which immunological factors form the humoral system?

A

Complement, lectins (collectins, ficolins), lectins prevent polysaccharide capsule bacteria from bindin, pentraxins, antimicrobial peptides

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4
Q

What is the adaptive immune system?

A

Highly specialized defense mechanism against specific pathogen-variable receptors that undergo maturation (DNA recombination), memory response

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5
Q

Which microbial factors are used in the adaptive humoral response?

A

Antibodies, complement

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6
Q

What immunological cells form the adaptive immune system?

A

Cytotoxic T cells, t helper cells, t regulatory cells, b lymphocytes, and plasma cells

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7
Q

What are the four main pathological niches?

A

Extracellular
Intracellular
surface adherent
Intracellular cytosolic

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8
Q

What are extracellular niches?

A

Staphylococcus, streptococcus, candida, microbiota (worms), Pathogens secrete toxins and are suspended in tissue

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9
Q

What are intracellular niches?

A

Salmonella requires host cell organelles to translate and synthesize proteins (viruses)

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10
Q

What are surface adherent niches?

A

Enteropathogenic and enterohaemorrhagic E.coli Require close proximity to host cells. Adhesive tips enable bacteria to attach to specific host cells receptors. Cell wall adhesins are surfaced proteins in the cell wall of bacteria that bind tightly to specific receptor molecules on host cell surface membranes

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11
Q

What are intracellular cytosolic niches?

A

Phagocytosed pathogen integrates and suspends in the cytosol of cell (Listeria)

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12
Q

What is the circulating life span of neutrophils?

A

6 hours, short lived, followed by macrophages

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13
Q

How are Naive neutrophils activated?

A

Activated upon interaction with the pathogen and are attracted towards the area of infection by chemotaxis

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14
Q

Which class of chemotactic protein is released for neutrophil chemotaxis?

A

Leukotrienes

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15
Q

Where do neutrophils arise from?

A

Bone marrow through differentiation of HSCs into lymphoid precursors, neutrophils are unable to replicate.

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16
Q

What is the purpose of phagocytes?

A

Control infection (undergoing phagocytosis to hydrolyse pathogens, reducing pathogenic load), and limit/repair tissue damage

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17
Q

What does unregulated phagocytic activity result in ?

A

Granuloma (Collection of neutrophils/macrophages that exclude of an area) formation; excessive inflammation and inappropriate adaptive immunity, and tissue damage

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18
Q

What are interleukins?

A

Are communicatory glycoproteins released by leukocytes that regulate immune response-cytokines

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19
Q

Which receptors does IL bind onto?

A

IL receptors, consequently contributing to gene expression of naive cells activates macrophages

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20
Q

What are the three stages that occur for the sequence of molecular and cellular events in terms of activation of host immunological cells?

A

1) Microbial ligand detection
2) Naive host cells undergo gene-expression changes
3) Cytokine and chemokine release causes signal transduction

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21
Q

Where do macrophages reside?

A

Tissue-resident or circulatory

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22
Q

Which cytokines induce macrophage activation?

A

IL-12/18/1, TNF & IL-6

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23
Q

What functions are displayed by activated macrophages?

A

Phagocytosis and migration; cytokine/chemokine production, expression of cell surface molecules; antimicrobial activity; antigen presentation and T cell activation

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24
Q

What inflammatory properties are expressed by activated macrophages?

A

They are anti-inflammatory

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25
Q

Which interferon is the primary activator of macrophages?

A

IFN-y

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26
Q

Which interferon induces Class II MHCs on macrophages?

A

IFN-y

27
Q

Which cells secrete cytokines which stimulate macrophage phagocytosis of pathogens?

A

T-lymphocytes

28
Q

How is the specificity of immunological response dictated by cytokines?

A

The specificity of the response is attributed to the definite secretion of cytokines that confers to particular gene expressions to respond to the pathogen

29
Q

What are interferons?

A

Interferon molecules are cytokines that express direct antiviral activities

30
Q

What do antiviral genes encode for?

A

Nucleases (cleaves terminals fo viral nucleic acid)
Inhibitors of viral entry and exit
Inhibition of viral uncoating and replication
Inhibitors of protein translation

31
Q

What are the three main immunomodulatory roles?

A

The enhanced T-cell response, anti-inflammatory actions, and tissue repair

32
Q

How are infected cells killed by the immune system?

A

Killed by the action of cytotoxic T lymphocytes (CTLs)/ natural killer (NK) cells.

33
Q

How are NK cells activated?

A

Independent of MHC recognition; are activated in response to secreted interferons or macrophage-derived cytokines. NK cells work to control viral infections by secreting IFN-y & TNF-a

34
Q

How do NK and CTL cells control viral replication?

A

Cell death stimulated by these cells, removes viral replication niches, reducing the rate of viral load increments
Directly kill infected cells through contact-dependent mechanisms

35
Q

How do intracellular bacterial infected cells undergo contract independent cell death?

A

Through cytokine stimulation

36
Q

What are the four soluble effect mechanisms of the humoral innate immune system?

A

Complement mediated
Lectin binding
Iron chelation
Antibiotic-like peptides

37
Q

What is the function of lectins?

A

Lectin-binding is responsible for the neutralization of cell attachment/entry

38
Q

What is the function of iron chelation by siderophores?

A

Prevents replications

39
Q

What are the 2 cell effector mechanisms for the humoral innate system?

A

Reactive oxygen and nitrogen radicals, acidification and digestion within phagosomes
Lysosomes secreted hydrolytic lysosomal enzymes that cleave pathogenic peptides within the phagocytic vacuole - components are expressed onto MHC molecules of cell surface membrane for adaptive immune response as an antigen-presenting cells

40
Q

Which MHC class is recognized by CD4 cells?

A

MHC-II

41
Q

Which MHC class is recognized by CD8 cells?

A

MHC-I

42
Q

Which immune cells are antigen-presenting cells?

A

Activated macrophages and dendritic cells

43
Q

Which interleukin secreted by antigen-presenting cells promotes T-cell replication?

A

IL-12

44
Q

Which cytokine upregulates MHC-II expression for antigen presentation?

A

IFN-y

45
Q

Which class of cells activate T-helper cells?

A

Dendritic cells and macrophages, the presented MHC-antigen complex associated with the cell membrane binds to complementary TCRs of the naive T-cells.
Binding mechanism results in the secretion of IL-2 cytokine causes mitotic division and specialization into active T-helper cells and T-memory cells

46
Q

Which interleukin is secreted from activated naive T-cells which stimulates subsequent mitotic division?

A

IL-2

47
Q

What do B-cell receptors detect?

A

Detect antigenic epitopes

48
Q

What happens to the bound antigen onto the BCR?

A

Through receptor-mediated endocytosis by the B cell, the antigen undergoes antigen processing, the processed peptide fragments are expressed by MHC molecules on the cell surface membrane, and are subsequently recognized by T helper cells with complementary CD4 t cell receptors

49
Q

What is the purpose of opsonization?

A

Mark infected cells, and pathogens, thus facilitating phagocytosis

50
Q

What is the purpose of Th1 cells?

A

The lineage of CD4+ affect T cells, that promotes cell-mediated immune responses, required for host defense against intracellular viral and bacterial pathogens
Th1 cells secrete IFN-y, IL2/10, TNF-alpha/beta
Macrophage activation

51
Q

What is the purpose of Th2 cells?

A

Mediate the activation & maintenance of the humoral and antibody-mediated immune response against extracellular bacteria, allergens, and toxins

52
Q

What are the two classes of innate immune T cells?

A

T delta & gamma, these are early responders and are MHC independent

53
Q

What is the principal target for Th1 cells?

A

Macrophages,

54
Q

What role do Th1 exhibit in disease?

A

Autoimmunity and chronic inflammation

55
Q

Which are the defining cytokines released from Th1 cells?

A

IL4/5/13

56
Q

What is the principal target cell for Th2 cells?

A

Eosinophils

57
Q

What are the main immune reactions stimulated by TH2 cells?

A

Eosinophil and mast cell activation
Alternative macrophage activation
Defense against helminths

58
Q

Which t cells are mainly evident in allergy?

A

Th2

59
Q

What are the defining cytokines released from Th17 cells?

A

Il17/22

60
Q

What are the primary target cells for Th17 cells?

A

Neutrophils

61
Q

What are the major immune reactions stimulated by Th17 cells?

A

Neutrophil recruitment and activation

62
Q

Which Th cell subset is responsible for defense against extracellular bacteria and fungi?

A

Th17

63
Q

What is Chediak-Higashi syndrome?

A

Compromised lysosomes

POM Y1 Imperial (34 decks)

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