A Brief Introduction To Immunology And Adaptive Immunity - 13/11 Flashcards
Define innate immunity
Instinctive, non specific, does not depend on lymphocytes, present from birth
Define adaptive immunity
Specific ‘acquired/learned’ immunity, requires lymphocytes, antibodies
What are both innate and adaptive immunity made up of?
Cells and soluble factors (humoural)
What layers are present in centrifuged blood?
Upper layer - plasma ( water 90%, electrolytes, proteins, lipids, sugars etc)
Middle layer - white fluffy layer, buddy cost - leukocytes
Lower layer 45% - erythrocytes, platelets (haematocrit)
Define haematopoesis
“The commitment and differentiation processes that leads to the formation of all blood cells from pluripotent haematopoietic stem cells.”
Name 3 polymorphonuclear leukocytes
Neutrophil
Eosinophil
Basophil
Name 3 mononuclear leukocytes
Monocytes, t-cells, b-cells
When monocytes exit blood stream and enter tissues what does it change into?
Macrophage
When T cells differentiate what 3 cells can they change into?
T-regs
T-helper (CD4) (Th1 &Th2)
Cytotoxic (CD8)
Name 5 cells of the immune system
Mast cell
Natural killer cells
Dendritic cells - skin
Kupffer cells - liver
Langerhans - skin
What are 3 main groups of soluble factors?
Complement
Antibodies
Cytokines, chemokines
Define complement soluble factors?
Group of ~20 serum proteins secreted by the liver that need to be activated to be functional.
Complement is activated only as part of the immune response.
What are the 3 main modes of action of complement soluble factors?
Direct lysis
Attract more Leukocytes to site of infection
Coat invading organisms
Define antibodies soluble factors?
Bind specifically to antigens (Ag)
What are Igs? And features
Immunoglobulin,
soluble
- secreted
- bound to B cells as part of B-cell antigen receptor
What are the 5classes of Igs
IgG (1-4)
IgA (IgA1 & 2)
IgM
IgD
IgE
What are Igs made of?
Glycoproteins
Structure of IgG
Y shape - fab ends and Fc ends (15th slide)
Where is IgM mainly found? Why?
Blood - too large to cross endothelium
Which have initial contact and primary immune response?
IgM and Ag
What is mIgM
Monomeric form of IgM present as antigen-specific receptor on b-cells
IgA
Slide 18
IgD
Slide 19
IgE
Slide 20
Antibodies
Slide 21
Define cytokines
Proteins secret3d by immune and non-immune cells
What is interferons (IFN)
induce a state of antiviral resistance in uninfected cells & limit he spread of viral infection
IFNa & b - produced by virus infected cells
IFNg - released by activated Th1 cells
What is interleukins (IL)
produced by many cells, over 30 types
Can be pro-inflammatory (IL1) or anti-inflammatory (IL-10)
Can cause cells to divide, to differentiate and to secrete factors
What are colony stimulating factors (CSF)
Involved in directing the division and differentiation on bone marrow stem cells – precursors of leukocytes
What is tumour necrosis factors (TNFalpha and beta)
Mediates inflammation and cytotoxic reactions
Define chemokines
Group of approx 40 proteins that direct movement of leukocytes (and other cells) from the bloodstream into the tissues or lymph organs by binding to specific receptors on cells
What are 4 different types of chemokines?
CXCL
CCL
CX3CL
XCL
What are CXCL
Mainly neutrophils
What are CCL.
Monocytes, lymphocytes, eosinophils, basophils
What are CX3CL
Mainly t lymphocytes and NK cells
What are XCL
Mainly t lymphocytes
What are 2 defence mechanisms?
Innate and adaptive
Features of innate immunity
1st line of defence
Provides barrier to antigen
Instinctive
Present from birth
Slow response
No memory
Features of adaptive immunity
Response specific to antigen
Learnt behaviour
Memory to specific antigen
Quicker response
What is the innate immunity composed of?
Physical and chemical barriers
Phagocytic cells (neutrophils and macrophages)
Blood proteins (complement, acute phase)
Name some physical barriers in innate immunity?
Mucus and cilia in bronchi, physical barrier of skin, lysozyme in tears, flushing of urinary tract
What happens when physical barriers are breached? Eg. Cut
Inflammatory response
General stages of inflammatory response
Stop bleeding (coagulation)
Acute inflammation (leukocyte recruitment)
Kill pathogens, neutralise toxins, limit pathogen spread
Clear pathogens/dead cells (phagocytosis)
Proliferation of cells to repair damage
Remove blood clot – remodel extracellular matrix
Re-establish normal structure/function of tissue
Define inflammation
‘A series of reactions that brings cells and molecules of the immune system to sites of infection or damage’.
What are 2 types of inflammation?
Acute and chronic
What are hallmarks of inflammation?
Increased blood supply
Increased vascular permeability
Increased leukocyte transendothelial migration ‘extravasation’
Define acute inflammation
Complete elimination of a pathogen followed by resolution of damage, disappearance of leukocytes and full regeneration of tissue
Loosely define chronic inflammation
Persistent, un-resolved inflammation
What are the 2 sensing microbes found on blood?
Monocytes and neutrophils
What are the 2 sensing microbes found in tissues?
Macrophages and dendritic cells
What receptors are found on cells?
PRR (pattern recognition receptors)
What receptors are found on microbes?
PAMP (pathogen associated molecular patterns)
What are the haemotractants o that bind to receptors on leukocytes in complement process
C3a and C5a
What are the receptors that insert onto bacterial membrane in complement process
C3b
What lyses microbes directly in complement process
MAC
What happens after extravasion of neutrophils towards sight of infection?
Phagocytosis
What are the 5 stages of phagocytosis?
- Binding to antigen on surface
- Engulfment
- Phagosome formation
- Phagolysosome
- Membrane disruption/fusion
See slide 42
What are 2 mechanisms of microbial killing present in neutrophils and macrophages?
O2-dependant (Reacticve oxygen intermediates (roi) —> superoxides and nitric oxides
O2-independent (enzymes e.g. lysozyme, proteins e.g. defensive, TNF and pH)
Where are primary and secondary lymphoid of t and b cells
See slide 50
Which immunity type (cell mediated or humoural) requires intimate cell to cell contact?
Cell mediated
Which cells do not respond to soluble antigens.
T lymphocytes, they only respond to intracellular presented antigens
T cells that recognise self cells are killed where?
In foetal thymus
What do major histocompatibility complex (MHC) display?
Self or non self proteins
What are the two types of major histocompatibility complex (MHC)?
MHC 1
MHC2
What is MHC 1 DO?
coded by HLA (A, B & C genes) - glycoproteins on ALL nucleated cells (graft rejection).
What does MHC 2 DO?
coded by HLA (DP, DQ& DR) - glycoproteins ONLY on APC.
Slide 58
Slide 61&62&63&65
B cells that recognise self are killed where?
Bone marrow