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ICB > Haematopoiesis > Flashcards

Haematopoiesis Flashcards

1
Q

Why study the immune system

A
  1. prospects for treatment of infection, autoimmunity, cancer, transplantation
  2. massive burden on health and society (susceptibility to disease, vaccine development, pathogen evasion)
  3. allergy/asthma
  4. autoimmune diseases (explanation & treatment)
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2
Q

Major Histocaompatbility Complex

A

highly polymorphic set of molecules unique to individuals which define our tissue type
- MHC haplotype determines immune ability and transplantation

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3
Q

Antigen

A

any molecule that is recognised by the immune system specifically by lymphocyte receptors

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4
Q

B cell receptors

A

antibodies/immunoglobulins - membrane bound or soluble

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5
Q

T cell receptors

A

TCRs are membrane bound proteins

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6
Q

Types of vaccines

A
  1. whole organism : killed or inactivated
  2. whole organism : live attenuated/weakened form
  3. subunit : purified product assembling into particles
  4. DNA/RNA : encoding selected protein antigen
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7
Q

Barriers to Infection

A
  1. skin
  2. gastrointestinal tract
  3. respiratory tract
  4. urogenital tract
  5. eyes
    - mechanical (epithelial cells joined by tight junctions), chemical (defensins), microbiological
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8
Q

Innate Immunity

A

cells and components of the immune system acting without prior pathogen exposure

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9
Q

Complement

A

cascade of proteolytic enzymes which promote inflammation/cytotoxicity

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10
Q

Inflammation

A
  • movement of cells to the site of infection
    1. healthy skin is not inflamed
    2. surface wound introduces bacteria activating resident effector cells to secrete cytokines
    3. vasodilation and vasular permeability allow cells to leave blood and enter tissue
    4. infected tissue is inflammed
  • cytokine: secrete protein changing the response and behaviour of neughbouring cells
  • short range hormones
  • also known as Interleukins
  • chemokine: chemoattractant cytokine attracting cells to a site of infection
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11
Q

Innate vs Adaptive Immunity

A

Innate

  • rapid
  • fixed response
  • limited specificity
  • constant during response

Adaptive

  • slow
  • variable
  • highly specific and selective
  • improves during response
  • both use common effector mechanisms for pathogen destruction
  • innate immunity is needed to prime the adaptive response and adaptive immunity is needed for pathogen clearance
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12
Q

Pattern Recognition Receptors

A
  • recognise pathogen associated molecular patterns

- macrophages express multiple receptors for recognition of molecules expressed by common pathogens

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13
Q

Toll Like Receptors

A
  • family of 10 genes recognising common pathogen molecules
  • pathogen recognition domain is a repeated sequence motif of 20-29 residues (leucine rich repeats)
  • homo or heterodimers
  • TIR (toll interleukin 1 receptor) domain is the intracellular signalling domain
  • ligand recognition produces cytokines for inflammation
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14
Q

Adaptive Immunity Principle

A
  • involves selection and expansion of lymphocytes with specific receptors fine tuned to antigen structure
  • during development progenitor cells give rise to large numbers of lymphocytes each with different specificities
  • during infection lymphocytes with receptors recognizing the pathogen activate
  • proliferation and differentiaiton of pathogen activated lymphocytes give effetor cells terminating the infection (finetune receptor to fit better)
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15
Q

B and T lymphocytes

A
  • have specific receptors for antigens
  • are selected and expanded during infection - adaptive immunity
    1. small naive B lymphocyte has membrane bound antibodies
    2. antigen activation induces cell cycle entry
    3. G1 = gene activation
    4. lymphoblast S phase
    5. cell division to form memory and effector plasma cells with are antibody secretion factories
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16
Q

Haematopoiesis

A

Haematopoiesis is the formation of blood cellular components. All cellular blood components are derived from haematopoietic stem cells.
- bone marrow produces blood cells

17
Q

Immune Cell Types in Blood

A
  1. neutrophil (most common)
  2. eosinophil
  3. basophil
  4. monocyte: macrophage precursor
  5. lymphocyte (second most common)
18
Q

Haematopoietic Stem Cells

A
  • give rise to myeloid and lymophoid cells
    Myeloid: differentiation into common myeloid precursor
  • megakaryocute/erythroid precursor
  • granulocyte/macrophage precursor
  • from the above a further macrophage and dendritic precursor

Lymphoid: common lymphoid precursor differentiation

  • NK/T cell precursor
  • B cell
19
Q

Functions of Haematopoietic Cells

A
  • small lymphocyte: production of antibodies or cytotoxic / helper functions (B and T cells)
  • plasma cell: fully differentiated form of B cell secreting antibodies
  • dendritic cell: T cell activation and initiation of adaptive immune responses
  • mast cell: expulsion of parasites from body via granule release
  • NK cell: kill cells infected with certain viruses
  • monocyte: precursor of macrohpage
  • macrophage: phagocytosis and killing of microorganisms/T cell activation/immune response initiation
  • neutrophil: phagocytosis and killing of microorganisms
  • eosinophil: killing of Ab coated parasites via granule release
  • megakaryocyte: platelet formation and wound repair
  • erythrocyte: oxygen transport
  • basophil: controlling immune response to parasites (cytokine source)
20
Q

Dendritic Cells

A
  • antigen presenting cells
  • pick up, process, and present antigen to activate lymphocytes
  • found in peripheral, and lymphoid tissues
21
Q

Macrophages

A
  • phagocytosis and destruction of cellular debris and pathogens
  • present antigen to lymphocytes as well
  • stimulate inflammation
  • bind bacteria to phagocytic receptors to induce engulfment and degradation or binding of bacterial components to signalling receptors induces inflammatory cytokine synthesis (transcriptional response)
22
Q

Opsonisation

A
  • coating with a molecule facilitating uptake (antibodies or complement)
  • micro-organisms are opsonised for uptake by phagocytic cells
23
Q

Neutrophils

A
  • front line of the immune response to infection
  • also phagocytic and cytotoxic =
  • lots in the bloodstream but short half-life
  • large reserves stored in bone marrow and deployed upon infection
  • travel and enter infected tissue engulfing and killing bacteria
  • they die in the process and are then degraded via engulfment by macrophages

ICB (15 decks)

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