At what site of the body are most infections acquired?
The mucosal sites; because the skin is a tougher barrier to penetrate.
Name an example for each of the following for how they act as a mechanical defence against infection:
- Skin
- Gastrointestinal
- Respiratory
- Urogential barrier
- Eyes
- Skin –> Flow of fluid: perspiration. sloughing off skin
- Gastrointestinal –> Flow of fluid: mucus, food, salvia
- Respiratory tract –> Flow of fluid: mucus by cilia. Air Flow
- Urogential tract –> Flow of fluid: urine, mucus, sperm
- Eyes –> Flow of fluid: Tears
Name an example for each of the following for how they act as a chemical defence against infection:
- Skin
- Gastrointestinal
- Respiratory
- Urogential barrier
- Eyes
- Skin –> Sebum (fatty acids, lactic acid, lysozyme)
- Gastrointestinal –> Acidity, enzymes (proteases)
- Respiratory tract –> Lysozyme in nasal secretions
- Urogential tract –> Acidity in vaginal secretions, spermine and zinc in sperm
- Eyes –> Lysozyme in tears
Name an example for each of the following for how they act as a microbiological defence against infection:
- Skin
- Gastrointestinal
- Respiratory
- Urogential barrier
- Eyes
- Skin –> Normal flora of the skin
- Gastrointestinal –> Normal flora of the gastrointestinal tract
- Respiratory tract –> Normal flora of the respiratory tract
- Urogential tract –> Normal flora of the urogenital tract
- Eyes –> Normal flora of the eyes
What is innate immunity?
Cells or compounds of the immune system which act without prior exposure to the pathogen
What is complement?
Complement is a series of proteolytic enzymes that promote inflammation and cytotoxicity. They form a cascade once activated.
In terms of activating complement, what is the alternative pathway?
Pathway in which a bacterial cell surface induces cleavage and activation of complement component c3
What is the name of the large component of c3 that stays bound to the bacteria after cleavage?
C3b
What is the name of the small component which diffuses away from the bacteria after cleavage of C3?
C3a
What is the role of C3a?
It is a chemoattractant which forms concentration gradient to which cells migrate.
What is the process of migration of cells towards the site of tissue damage of infection called?
Inflammation
In order to cause inflammation what do cells in tissues release to increase vascular permeability?
Chemoattractants make blood vessel more permeable
In inflammation what causes you pain?
Increased pressure in the tissues
Immunity involving selection and expansion of lymphocytes with specific receptors fine-tuned to antigen structure is known as what?
Adaptive immunity.
During development each lymphocyte will have thousands of receptors but on one cell all antibodies will be the same. True or False.
True
Upon recognition and proliferation and differentiation of appropriate lymphocytes you generate…..?
Memory Cells
What is haematopoiesis
The generation of cells in the blood
Where does haematopoiesis take place in embryos?
The yolk sac
Where does haematopoiesis take place in foetus’?
Liver and spleen
Where does haematopoiesis take pace in adults?
Bone marrow
Pluripotent haematopoietic stem cells (HSC) differentiate into what?
Lymphoid or myeloid progenitors.
What do myeloid progenitors differentiate into?
Megakaryocyte/erythrocyte and Granulocyte/macrophage progenitors
Megakaryocyte progenitor gives rise to…?
Platelets which are involved in clotting
and
Red blood cells
Granulocyte progenitors give rise to what 3 main cells types?
For bonus points what are the other three?
Neutrophil
Basophil
Eosinophil
Bonus round:
Monocytes
Mast cell progenitor
Immature dendritic cells
Lymphoid progenitors give rise to what 3 main cell types?
T cells
B cells
NK cells
Where are lymphocytes activated?
lymph nodes
Where do T cells mature?
Thymus
Where do B cells mature?
Bone marrow
What are cytokines?
Short range small proteins (not hormones!) that are released by cells of the immune system that influence behaviour of other cells. Often affect transcription factors and hence differentiation by the JAK-STAT pathway
What is the half life of Eosinophils?
30 mins
What is the half life of Neutrophils?
6-12 hr
What is the half life of an NK cell?
6-10 days
What is the half life of memory cells?
several years
Where are macrophages found?
Tissues not blood. (monocytes leave blood stream and differentiate into macrophages)
Macrophages have receptors for complement. True or False.
True
Macrophages binding bacteria leads to release of what?
Inflammatory cytokines
Why are granulocytes called granulocytes?
They contain granules in the cytoplasm. The granules are secretory vesicles
Match the general pH (acidic, basic, neutral) of the cell to the granules of these cells:
Neutrophils
Eosinophil
Basophil
Neutrophil –> Neutral
Eosinophil –> Acidic
Basophil –> Basic
Where are neutrophils stored in large reserves?
The bone marrow. During infection they move to blood stream and migrate into tissues.
What engulfs neutrophils after they have self destructed in the process of killing bacteria?
Macrophages
B cells differentiate into plasma cells and secrete what?
Antibodies
T cells and NK cells are specifically adapted to attack intracellular or extracellular pathogens?
Intracellular
What is a naiive lymphocyte?
A lymphocyte that has its receptors and is mature but isn’t activated.
Naiive B cell activation leads to …?
Plasma cells that create antibodies
or
Memory cells
Naiive t cell activation leads to …?
Population expansion, differentiation and memory cells
Where are pseudopodia found and what is their purpose?
Found on the outer surface of macrophages. Trap bacteria.
What enzyme catalyses the cleavage of C3 in the alternative complement pathway?
C3-convertase
How is the differentiation of hematopoietic stem cells regulated?
Different transcription factors direct cells towards different lineages. Expression of different transcription factors is influenced by cytokines.
