M: Immune System and Response to Infection - Week 4 (lec 10) Flashcards
Name the 4 principles of immune responses
- Immunological recognition
- Immune effector functions (e.g. binding, death mediation)
- Immune regulation (ability to up or downregulate response)
- Immunological memory (allows faster response to known pathogens)
Explain immunological recognition. How does our body discriminate between molecules? What receptors are used?
Recognition of ‘self’ and ‘non-self’.
Microbial molecules are discriminated by:
- PAMPs (pathogen associated molecular patterns)
- Antigens
These features are recognized by PRRs (pattern recognition receptors) and Antigen receptors respectively.
Explain PAMPs, and state whether innate or adaptive responses are directed against it
PAMPs – are unique to microbes but are shared within discrete taxonomic groups (e.g. LPS) – they are directed against by INNATE responses
(adaptive is directed against antigens)
How does microbial invasion work to take over the body and produce symptoms? Explain how it’s a race between the immune system and invading microbes
The race is between microorganisms replicating vs our immune system response.
The immune system tries to reduce the number of microorganisms to prevent them from reaching a ‘multiplication threshold’, at which point the microbes then switch into a disease producing mode where they produce pathogenic factors etc.
What three kinds of barriers act as a 1st line of defense (non-specific immunity)? Are there any other 1st line defenders?
- physical barriers (e.g. skin)
- chemical barriers (e.g. mucus, saliva)
- mechanical barriers
also: cells that kill and defensive molecules
What type of cells act in specific immunity?
- cells that kill
- cells that make antibodies
- cells that help other cells
- cells that remember and prevent reinfection
What are primary lymphoid organs? Name them
are the organs where our immune cells are generated
- these include the bone marrow, and (for lymphocytes) the thalamus
– our innate immune cells are generated from progenitors in the bone marrow
Where do b-lymphocytes mature? What about t-lymphocytes?
b-lymphocytes: In the bone marrow
t-lymphocytes: in the thymus
What are secondary lymphoid organs? Name them
are where we find our lymphocytes in particular
- these include: the spleen, adenoids, tonsils, and the various lymph nodes scattered throughout our body
Compare the diversity of microbes recognised by the innate and adaptive immune systems
Innate: limited amount of microbes recognised; germline encoded
Adaptive: very large; somatic recombination of gene segments
Compare the response speed and magnitude for the innate and adaptive immune systems
Innate: rapid response, constant magnitude
Adaptive: slower response, magnitude increases with multiple exposures
Compare the cellular and chemical barriers for innate and adaptive immune systems
Innate: skin, mucosal epithelia, antimicrobial molecules
Addaptive: lymphocytes in epithelia, antibodies secreted at epithelial surfaces
Compare the blood proteins for innate and adaptive immune systems
Innate: complement, others
Adaptive: antibodies
Compare the cells found for the innate and adaptive immune systems
Innate: phagocytes, NK cells
Adaptive: lymphocytes
What is the role of lymphatic vessels?
They connect lymph nodes and are there to drain our tissues to deliver antigens to the lymph node, so that the lymphocytes are then activated.
From there they all collect and then empty into the blood stream.
What is the role of lysozyme in the immune system, and where is it found?
Lysozyme is found in tears and other secretions, and is an enzyme that acts as a 1st-line of defence by acting on the peptidogycan layer in bacteria (particularly gram +ve bacteria)
How are dendritic cells beneficial to our immune response?
They are cells that express PRRs that can recofnise foreign invaders.
AND MOST IMPORTANTLY: they are very potent cells in delivering the antigens of those foreign invaders to the lymph nodes where they can activate T- (and B-) lymphocytes
– so they act as a kind of link to the adaptive response
Explain the process of ‘colonisation’ of microbes
(Usually is the start of the infection process.)
Colonisation involves the adherence of the invading organisms and interaction with epithelial cells.
colonisation may occur to an external surface or internal surface (e.g. GI tract)