L1 - An overview of immunology Flashcards

1
Q

What is an antigen

A
  • Anything the immune system to responds do
  • Usually protein
  • Not necessarily ‘bad’
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2
Q

Function of an antigen receptor

A
  • Recognises the antigen
  • Fundamental basis of immunity
  • Basis of division into innate and adaptive
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3
Q

What is an effector mechanism

A
  • An action to respond to the antigen
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4
Q

Type of stem cells produced by the bone marrow

A
  • Pluripotent hematopoietic stem cells
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5
Q

What can the pluripotent hematopoietic stem cell differentiate into

A
  • Common lymphoid progenitor

- Common myeloid progenitor

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6
Q

What can the common lymphoid progenitor cell differentiate into

A
  • B cell
  • T cell
  • NK cell
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7
Q

What can a common myeloid progenitor cell differentiate into

A
  • Granulocyte/macrophage progenitor

- Megakaryocyte/erythrocyte progenitor

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8
Q

What can a granulocyte/microphage progenitor cell differentiate into

A
  • Neutrophil
  • Eosinophil
  • Basophil
  • Unknown precursor of mast cell
  • Monocyte
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9
Q

What do megakaryocytes differentiate into

A
  • Platelets
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10
Q

What do erythroblasts differentiate into

A
  • Erythrocytes
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11
Q

What do monocytes differentiate into

A
  • Macrophages
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12
Q

What cells can differentiate to form immature dendritic cells

A
  • Hematopoietic bone marrow progenitor cells
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13
Q

Function of neutrophils

A
  • Phagocytosis
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14
Q

Function of eosinophils

A
  • Helminth infections??
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15
Q

Function of monocytes(circulating macrophage tissue)

A
  • Phagocytosis

- Antigen presentation

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16
Q

Function of dendritic cells

A
  • Antigen presentation
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17
Q

Function of basophils (tissue-resident counterpart = mast cell)

A
  • Helminth infections
18
Q

Features of lymphoid lineage

A
  • Similar size to RBC

- Little cytoplasm with few granules

19
Q

Functions of B cells

A
  • Make antibody, antigen presentation
20
Q

Functions of T cells

A

CD4 - Help other components of immunity

CD8 - Kill infected cells

21
Q

Type of immunity provided by T cells and B cells

A
  • Adaptive immunity
22
Q

Features of NK cells

A
  • Actually innate lymphocytes

- Direct lysis of infected cells and antibody-dependent cellular cytotoxicity

23
Q

Types of intercellular signalling

A
  • Endocrine
  • Paracrine
  • Autocrine
  • Juxtacrine
24
Q

What are cytokines

A
  • Cytokines are small proteins released by cells that have an effect on another cell
25
Q

Why are cytokines important

A
  • They are important for communication between cells of the immune system and between immune system cells and other cells and tissues
26
Q

Cytokines vs Chemokines

A

Chemokines are similarly defined, but

  • Different structure, receptors and nomenclature
  • Main role is temporal and spatial organisation of cells and tissues
27
Q

Key features of innate antigen receptors

A

Do not recognise antigen specifically

  • Pattern recognition receptors’ (PRRs)
  • Recognise ‘pathogen associated molecular patterns’ (PAMPS)
  • Genome-encoded
  • Not clonally distributed
28
Q

What do manose binding ligands bind to?

A
  • MBL binds with high affinity to mannose and fucose residues with correct spacing
  • Mannose and fucose residues that have different spacing are not bound by MBL
29
Q

Classical features of innate immune receptors/defences

A

Work quickly - first line of defence
Adaptive immunity takes more time to be activated
Unable to ‘learn’, as germline encoded and therefore cannot change - therefore no memory

30
Q

Key features of adaptive antigen receptors

A
  • Recognise antigen specifically
  • T cell receptor, B cell receptor (antibody)
  • Huge receptor diversity
  • Clonally distributed
  • Permit specificity and memory in immunity
31
Q

How are adaptive antigen receptors produced

A
  • Produced by random somatic recombination events between gene segments
32
Q

Features of B cell receptors

A
  • May be surface-bound or secreted

- Recognises intact antigen

33
Q

Features of T cell receptors

A
  • T cell receptor is very similar to the B cell receptor
  • Only a surface receptor on CD4 and CD8 T cells
  • Recognises processed antigen in the form of linear peptides
34
Q

How do somatic recombination events occur

A
  • T and B cell receptors are produced by random recombination events between V, (D) and J gene segments, producing a huge receptor diversity despite a small number of genes
  • The most useful receptors are selected after birth upon exposure to pathogens
35
Q

What happens to clonally-expanded T and B lymphocytes after primary infection

A
  • After primary infection, most clonally-expanded T and B lymphocytes die off; a few remain as long-lived memory cells
36
Q

Examples of effector mechanisms

A
  • Barriers (skin, acid pH in gut etc)
  • Cytokines
  • Complement
  • Phagocytosis(enhanced by opsonisation)
  • Cytotoxicity (CD8 T cell, NK cell)
  • Antibody-dependent cellular cytotoxicity
  • Mast cell and eosinophil degranulation
37
Q

Are effector mechanisms specific to types of immunity

A
  • Effector mechanisms are shared between innate and adaptive immunity
  • Adaptive immunity is defined by its receptors, not by its effector mechanisms
38
Q

How do CD8 T cells function

A

Antigens inside a cell are bound to class I MHC molecules, and brought to the surface of the cell by the class I MHC molecule, where they can be recognized by the T cell.

If the TCR is specific for that antigen, it binds to the complex of the class I MHC molecule and the antigen, and the T cell destroys the cell.

In order for the TCR to bind to the class I MHC molecule, the former must be accompanied by a glycoprotein called CD8, which binds to the constant portion of the class I MHC molecule.

Therefore, these T cells are called CD8+ T cells

39
Q

Features of acute inflammation

A
  • Hot
  • Painful
  • Red
  • Swollen
40
Q

Blood vessel changes that underlie the process of acute inflammation

A
  • Vasodilatation
  • Adhesion molecules
  • Increased permeability
  • The clinical features are therefore defined by an interaction between the pathogen and host immunity