Haematopoiesis (and Immune System Overview) Flashcards
An overview of the Immune System, and a general look at its different aspects.
What is immunology?
a branch of biochemical / biomedical science that is concerned with
the molecular, cellular and biochemical processes involved with how
the body defends itself against disease
What do immunological processes protect?
Immunological processes protect / defend our bodies against infectious
disease as well as non-communicable diseases such as cancer
What do immune cells recognise?
recognise ‘self’ from ‘non-self’ or ‘altered-self’.
Receptors on the surface of immune cell membranes recognise what?
protein markers of ‘self’
Self-reactive immune cells are weeded out
through …
… positive selection during lymphocyte
maturation
Pathogen associated molecular patterns
(PAMPs) are …
… ‘non-self’ molecules
What are PAMPS?
Pathogen associated molecular patterns
what recognises PAMPs?
Immune cell receptors
such as, toll-like receptor
(TLR), recognise PAMPs
Whats MHC?
Major Histocapability Complex (MHC)
What do PAMPs include ?
lipopolysaccharide (LPS), lipoteichoic acid, flagellin,
peptidoglycan (bacteria) and dsRNA (viruses)
Innate immunity can be…
… cellular or not
What components of the innate immune system are NOT cellular?
Physical barrier
Skin
Mucosa
Sebaceous glands
Goblet cells
What is the purpose of physical barriers?
purpose to keep foreign invaders out
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What is the function of lysosymes?
hydrolyses NAG-NAM
glyosidic bonds (gram +ve bacteria)
whats Human B1-defensin?
a poly-peptide with positively charged and
hydrophobic regions, that creates pores in the membrane
What is Human B1-defensin secreted by?
epithelial cells
What are complement proteins?
plasma pro-proteins that are activated in a
cascade creating the membrane attack complex
What are the innate immune cells?
Neutrophil
Eosinophil
Basophil
Monocyte
Innate immune cells are activated against what?
Innate immune cells are activated against
‘non-self’ antigen
non-specifically via
PAMP recognition
What are granulocytes?
cytosolic granules, multi-lobed or bi-lobed nuclei
contain granules which kill cells in response to receptor activation.
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What percentage of all leukocytes are neutrophils?
50 to 70%
What are neutrophils important for?
important for bacterial and fungal infections, last only hours to a few days in circulation
what does adaptive immunity involve?
Involves humoral and cell mediated responses that involve the T and B lymphocytes
Adaptive immune responses are…
… specific
Adaptive immune responses are ‘specific’.
What does this mean?
each lymphocytes
activation receptor will recognise a specific antigen lymphocyte is different.
What do humoral responses involve?
involve the production and secretion of immuno
globulin proteins (antibodies) – B lymphocytes
What do cell mediated responses invovle?
involve cytotoxicity – T lymphocytes (lots of
different types)
What percentage of leukpcytes are lymphocytes?
30% of leukocytes
What can lymphocytes form?
can form memory cells which can last for years (basis of vaccination)
Define antigen
“substance that is capable of inducing an immune response”
Antigens can be…
‘non-self’, ‘altered-self’ or ‘self’
What antigens are ‘non-self’?
Foreign invaders microorganisms
- Endotoxins (bacteria) - Exotoxins (bacteria)
what antigens are altered self?
- Viral infected cells
- Malignant cells
What antigens are autoimmune ?
to attack self.
Define epitope
Immunogenic region of an
antigen – important for
adaptive immunity
WHats haematopoiesis?
blood cell development
All blood cells (leukocytes and erythrocytes)
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Haematopoietic stem cells (HSC) are…
‘multi-potent’
Haematopoietic stem cells (HSC)
are ‘multi-potent’ and able to
differentiate into: ?
- Leukocytes
- Erythrocytes
- Platelets
The process of haematopoiesis is under…
under strict regulation &
ensures that blood cell
development occurs in
accordance with specific needs
The initial step in haematopoiesis
is …
… to whether follow a ‘myeloid’ or an ‘lymphoid’ differentiation path – committed
Specific cytokines & chemokines dictate…
… the direction that haematopoietic stem cells differentiate
What drives HSC differentiation to a common lymphoid progenitor?
FLT-3 ligand, tumour necrosis factor (TNF-α),
transforming growth factor (TGF-β) in
combination with (interleukin
) IL-2, IL-7, IL-12
and stromal cell derived factor (SDF-1)
what drives HSC differentiation to a common lyeloid progenitor?
- GM-CSF = granulocyte
macrophage colony stimulating factor - G-CSF = granulocyte colony stimulating factor
- EPO = erythropoietin
- TPO = thrombopoietin
- SCF = stem cell factor
How are blood cells distinguished?
Blood cells are distinguished by light microscopy following
haematoxylin and eosin (H&E) staining.
What colour do eosinophils stain?
stain red since cytoplasmic vesicles contain basic proteins that bind ‘eosin’ an acid dye
What colour do basophils stain?
stain blue as they bind the basic dye ‘haematoxylin’
What defines a set of diseases known as leukaemia?
Blockade in haematopoiesis
leukaemia can occur at various stages during…
… myeloid or lymphoid development
(myeloid leukaemia / lymphoid leukaemia).
Genetic mutations prevent…
… normal differentiation, leading to over proliferation of ‘non-functional’ blast cells (cancer)
What happens in the bone marrow due to genetic mutations?
Bone marrow over-crowded, reduced normal functioning blood cells
(symptoms), bone marrow failure and death
What are the primary sites (organs) of the immune system?
Thymus (T cells)
Bone marrow (granulocytes B cells)
what are primary lymphoid organs?
Sites in the body where granulocytes / lymphocytes are synthesised
(and matured) in an antigen independent setting
What occurs at the primary lymphoid organs?
- lymphocyte generation and education
- central selection
- diversification
What are secondary lymphoid organs?
Sites where immuno-competent T and B lymphocytes are exposed to antigen (activated) through antigen presentation processes
What are the secondarey lymphoid organs?
1) Lymph nodes (antigen from extracellular tissue fluid)
2) Spleen (antigen from blood)
3) Mucosal Associated
- Lymphoid Tissue (MALT) Peyer’s patches (gut),
appendix, tonsils and adenoids
