Lecture 1 - Overview Flashcards
How and when did Edward Jenner develop the first vaccination??
In 1796, noticed milk maids fair skin, pustules on hands from unfatal cow pox, infected boy with cow pox, boy survived, cow pox conferred protection against fatal small pox
What is a commensal organism?
Where one organism benefits and the other is unaffected
What is a mutualism?
Where both organisms benefit
What is a parasitism?
Where one organism benefits at the expense of the other
Most bacteria are… commensal mutual or parasites?
Most bacteria are commensal
Where do bacteria play an important role in the body?
fermentation, digestion, absorption or nutrients
What are pathogens?
Organisms that cause disease; virus, bacteria, fungus, parasites
What are the three barries your body has to protect against infection?
1) Mucosal barriers 2) Innate immune system 3) Adaptive immune system
What are the bodies mucosal barriers?
Skin 2m, Respiratory tract 120m, Intestines 200m
What are features of the innate immune system?
1) Immediate and act within minutes
2) recognise foreign pathogens via germline encoded receptors
3) No memory
What are features of the adaptive immune system?
1) days to develop
2) highly specific, requires sophisticated rearrangement of receptor genes
3) generates memory
Define Haematopoiesis
the development of blood cells from stem cells in the bone marrow (haematopoietic stem cells)
What are the two lineages that derive from the haematopoetic stem cell in the bone marrow?
Lympoid lineage and the Myeloid lineage
What cells derive from the Lymphoid lineage?
B lymphocyte, T lymphocyte, NK cells
What cells derive from the Myeloid lineage?
Granulocyte (macrophage progenitor) from which the granulocytes [neutrophils, eosinophils, basophils] , monocytes [dendritic cells, macrophages] and unknown mast cell progentior [mast cell] develop. ALSO MEGAKARYOCYTES AND RBC
What are the 4 major immunological tissues?
1)Bone marrow [haematopoietic stem cells come from]
2) Thymus [T cells develop]
3) Spleen [immune responses]
4] lymph node and peyers patch [secondary lymphoid tissue]
What are the three types of phagocytes?
1) Macrophages
2) Granulocytes
3) Dendritic cells
What are the features of the phagocytic cells?
- detect ‘particulate’ material and seek to remove
2) aided by limited number of receptors which recognise broad molecular patterns not present in eukaryotes
3) Do not vary
What is the function of macrophages?
- phagocytosis (antigens, pathogens and bacteria) and activation of bacterial mechanisms
- trigger the release of factors e.g. chemokines and cytokines, recruit neutrophils
- induce inflammation
Who discovered macrophages and how?
Llya Ilyich Mechnikov (late 1800s)
Stuck thorns into starfish (no adaptive only innate) to discover macrophages
Where are macrophages found?
In all peripheral tissues
What are the functions of neutrophils?
- phagocytise (ingest and kill bacteria)
- activate bacterial mechanisms
- recruited by macrophages, migrate rapidly from site of infection
- release granules that contain toxic components
What happens when neutrophils invade the site of infection?
1) Bacteria trigger macrophages to release cytokines + chemokines
2) Proteins and fluids move out of the blood vessel into site of infection (redness and swelling)
3) Inflammatory cells (neutrophils) migrate into tissue releasing further inflammatory mediators
How can we visualise the invasion of neutophils into a s.o.i?
Neutrophils express GFP
What occurs when neutrophils die?
collect into a white pus containing dead cells and neutrophils
What is the general pathway of the innate immune system?
1) activation of tissue macrophages
2) phagocytation and attraction of neutrophils
3) influx of neutrophils leads to localised inflammation, redness, heat and pain
What are B cells and what are their features?
- speicialised form of lymphocyte
- express antigen specific receptors
- produce soluble or membrane bound antibodies which recognise 3d shape of an antigen, the eptiope on surface of antigen (mostly anything)
What are the two types of T cells and what are their features?
1 - Killer T cell (cytotoxic T cell)
2 - T helper cells - help B cells make antidbodies
-express T cell receptors only recognise peptides
What is the structure of an antibody?
2 variable regions (antigen binding site)
a constant region (effector function-
2 light chains and 2 heavy chains (joined by disulphide bond)
What is the T cell receptor structure?
- alpha and beta variable region (antigen binding site)
- constant region
What is an antigen
any molecule capable of being recognised by an antibody or T cell receptor
What is the general peptide presentating process in T cells?
1) Antigen broken down into peptide fragments
2) epitope peptide binds to MHC molecule
3) T cell receptor binds to complex of MHC and epitope peptide
What are dendritic cells and what are their features?
Dendritic cells are phagocytic cells that degrade pathogens
- for activation immune response
- characterised by long dendritic processes
- migrate from peripheral tissue to lymph node and initiate AIR
- actively survey peripheral tissues
- actively transport antigen from s.o.i to lymph node
Who discovered dendritic cells?
Ralph Steinman
How are dendritic cells transported from s.o.i. to lymph node?
Through the lymphatic vessel network lymphatic capillaries to transport, drain into local lymph nodes, back into circulation through the subclavian vein
What is the importance of the lymphatic vessel network?
- allows migration network for dendritic cells and lymphocytes
- allows fluid drainage from peripheral tissues
What is Elephantiasis?
condition where lymph nodes are blocked leading to lymphodema
Where are lymph nodes found?
at drainage sites in the lymphatic vessel network
What are afferent lymphatic vessels?
Those collecting into a lymph node
What are efferent lymphatic vessels?
Those leaving lymph nodes
What are lymph nodes?
Highly specialised organised tissues with specific functions for each area e.g. the B cell follicle (antibody response generated) and the T cell paracortex (interaction of T cells and dendritic cells, T helper cells help to make antibody)
What is sepsis?
Where severe bacterial infection within the blood
What organ prevents sepsis and how?
SPLEEN - 95% blood filters though 3 mins
- Removes damaged RBC
- Removes bacteria, white pulp regions where immune cells reside, organismed to respond and pick up pathogens and filter blood out
What is the difference between primary and secondary lymphoid tissue?
Primary - where immune cells develop
Secondary - Where immune response occurs (lymph node, pyrus patch and spleen)
