imm 1 Flashcards
What are some vital things pathogens need to be able to survive in our body?
Lots of nutrients Correct temperature and PH Water
What does our immune system provide protection from?
Pathogens and parasites
Give some examples of pathogens
- Bacteria
- Viruses
- Fungi
Give some oral diseases that are caused by bacteria
Congenital syphallis
Periodontal disease
Hutchinsons incisors
Give some oral diseases that are caused by viruses
Primary herpetic gingiostomatitis| Kaposi’s sarcoma (HIV)
Give some oral diseases that are caused by fungi
Oral thrush= fungal candida
Vertebrate immune defences has how many immune layers
3 layers:1. Physical and biochemical barriers 2. Innate immune system 3. Adaptive immune system
Describe the physical barriers we have to disease
They are provided by our epithelial layers like skin and mucosal layers
What initiated the adaptive immune system?
The innate system
What are the 2 types of physical defences
Strong external barriers| More vulnerable mucosal membranes
Give examples of strong external barriers
- Skin2. Nails 3. Hair
Give examples of more vulnerable mucosal membranes
- Oral mucosa 2. Sinuses 3. Respiratory tract 4. Kidneys 5. Bladder6. Intenstines7. Eyes and oral cavity 8. Gastrointestinal tract
What type of barriers do surface epithelia provide to infection?
Provides
1. mechanical
2. chemical
3. microbiological barriers to infection
What type of mechanical barrier does the skin provide in response to infection?
- Have epithelial cells joined by tight junctions| 2. Longitudinal flow of air or fluid
What type of chemical barrier does the skin provide in response to infection?
- The epithelial cells produce fatty acid| 2. They also produce beta defensives lamellar bodies and cathelicidin
What type of mechanical barrier does the gut provide in response to infection?
- Have epithelial cells joined by tight junctions| 2. Longitudinal flow of air or fluid
What type of chemical barrier does the gut provide in response to infection?
- Has a low pH2. Produces enzymes like pepsin 3. Produce alpha defensins (cryptdins), reg III and cathelicidin
What type of mechanical barrier do the lungs provide in response to infection?
- Have epithelial cells joined by tight junctions| 2. Have cilia that move mucosa
What type of chemical barrier do the lungs provide in response to infection?
- Pulmonary surfactant| 2. Produce alpha defensins and cathelicidin
What type of mechanical barrier do the eyes nose and oral cavity provide in response to infection?
- Have epithelial cells joined by tight junctions 2. They eyes produce tears3. Nasal cilia
What type of chemical barrier do the eyes nose and oral cavity provide in response to infection?
- Enzymes in tears and saliva- lysozyme| 2. Produce histatins and beta defensins
What type of enzyme is lysozyme?
glycosidase enzymes
What is lysozyme most active against?
Gram positive bacteria
Give examples of some gram positive bacteria
Streptococcus mutans (cariogenic).
Why is lysozyme more active against gram positive bacteria?
As it is easier to get to heir peptidoglycan layer
What does lysozyme cleave?
The bonds between different types of sugars| It digest peptidoglycan
What does the activity of lysozyme end up exposing?
A portion of the lipid bilayer in the bacterial cell membrane
What is the exposed portion of bacterial lipid bilayer vulnerable to?
Invasion from other molecules like antimicrobial peptides
What are antimicrobial peptides synthesised as?
As inactive proform
What is a zymogen?
An inactive form of an enzyme usually needs proteolytic cut to become active
What are the 3 types of antimicrobial peptides present in humans?
- Defensins2. Cathelicidins3. Histatins
Describe defensins
- They are amphipathic| 2. They are insertion in membranes that generate pores causing membranes to become leaky killing the bacterial cell
What are the different types of defensins we may have?
Alpha defensins produces by specialised innate immune cells| Beta defensins produced by epithelial cells
Describe Cathelicidins
- It’s amphipathic2. It causes membrane disruption3. Has immuno-regulatory properties
What type of cathelicidins do humans possess?
LL-37 ONLY
What are Histatins produced by?
The parotid, sublingual and submandibular glands
Describe Histatins
- They are Histadine rich| 2. They are active against fungal pathogen
Describe the response speed of the innate system
Minutes to hours| Innate system is always present
Describe the response speed of the adaptive system
Takes upwards of 4 days to initiate | It is usually silent and needs a response to be activated
What is our immune system essentially doing when it is recognising what needs to be attacked?
It is determining what is a host cell and what is a non self cell by using the antigens present on cells
Describe the lasting protecting/ memory of the innate immune system
It has no memory
How does our immune system recognise what is self and non self?
By using antigens which are proteins on the surface of all cells
Describe the lasting protecting/ memory of the adaptive immune system
Provides immunity for years as it produces memory cells
In which group is the earliest form the adaptive immune system present?
Present in the Agnathans group (include lamprey)
Phyla that were formed before the agnathans have what type of immunity?
Only innate
What does the innate immune system provide?
Provides initial defences It limits pathogen proliferation and spread.It can control less virulent pathogens.
What is an important job of the innate immune system?
It induced the adaptive immune response
What does PMN stand for?
Polymorphonuclear neutrophils
Approx how much encoding space do we have in our genome?
25,000
What problem is caused due to the large diversity of pathogens?
We cannot encode all the different pathogen antigens into our gremlin as there is not enough space in out genome
What does immunological memory give us?
Immunological memory gives more efficient and effective immune response to previously seen pathogens.
When was the compliment system discovered and by who?
Discovered in 1890s by Jules Bordet
What are the functions of the compliment system?
- Facilitates recognition of bacteria by phagocytes| 2. Can directly lyse bacteria
What do phagocytic cells do?
They engulf bacterial then digest and degrade them
Approx how many plasma proteins make up the complement system?
Over 30
What does the compliment system work as?
A zymogen activation cascade
What does the detection of a few pathogens do to the number of phagocytes?
It leads to a rapid, amplified response
Define pathogen
A microorganism that causes disease (pathology) when it infects a host, includes bacteria, viruses, fungi.
Define self
A structure or molecule that is derived from the host
Define non-self
A Component or molecule that is immunologically recognised as foreign.
How many pathways are there to activate the compliment systems?
3
What are the 3 pathways that can activate the compliment systems?
- The lectin pathway2. The classical pathway3. The alternative pathway
Where do all 3 pathways converge?
Onto a single enzymatic activity which is called the C3 convertsase activity
On to what activity do all three pathways converge to?
The C3 convertase activity
What does C3 convertase do?
It cleavages C3 to form C3a and C3b which in turn mediates release of C5a.
What are the three outcomes of the single convergence to C3 converts activity
- C3a and C5a recruit phagocytic cells to the sire of infection prompting inflammation 2. Phagocytes with receptors for C3b engulf and destroy the pathogen more efficiently 3. Completion of the complement cascade leads to formation of MAC which disturbs cell membrane and causes cell lysisi
What does MAC stand for
Membrane-attack complex
Which of the 3 pathways was discovered first?
The classical pathway
What initiates the classical pathway?
When C1q interacts with a pathogen surface or with antibodies bound to the surface
What forms the C1 complex?
C1q, C1r, C1s
What does the classical pathway lead to?
Formation of the C3 convertase activity
What initiates the alternative pathway?
C3 undergoes spontaneous hydrolysis to C3(H2O)| This initiates the eventual deposition of C3 convertase the microbial surfaces
What makes up the complex formed in the alternative pathway?
Factor DFactor BFactor P These 3 form C3bBb
What initiates the lectin pathway?
Mannose- binding lectin (MBL) and ficolins recognise and bind to carbohydrates on pathogen surfaces
What does the lectin pathway lead to?
Formation of the C3 convertase activity
C3 is broken down into _______ and _______ by ____________
- C3a2. C3b3. C3 convertase
C3a and C5a act as what?
Anaphylatoxins
C3a and C5a do what?
They attract innate cells to where they are needed
What does C3b?
Help the phagocytes see pathogens that need to be engulfed
What does C5b do?
Forms a complex with C6, C7 and C8 and this complex inserts itself into the membrane of the bacterial cellThis then recruits a lot of molecules of C9 leading to pores forming in the bacterial membrane causing leakage and eventually death
What activates a zygmogen?
Another proteolytic enzyme must cut (cleave) it
What is congenital syphilis?
Infection prior to birth w treponema pallidum = teeth deformation
Define anaphylatoxin
Complement fragments generated following
activation of the complement system. Recognised by specific receptors they recruit
innate immune cells to a site of infection and inflammation
How is saliva a barrier of defence?
Saliva contributes to both the physical barrier by acting as a flushing agent, washing the
microbes into the gut, and delivers chemical defences such as lysozyme and
antimicrobial peptides (Histatins, defensins, cathelcidin
How is mucus a barrier of defence?
Mucus provides a barrier containing mucin glycoproteins preventing bacterial adhesion
to epithelia and is removed by the beating of cilia
Special feature of gram negative that prevents lysozyme attack?
Outer lipid membrane, covers peptidoglycan
What is the response speed for adaptive response?
-more potent activity to control more virulent pathogens
-takes time to raise population of cells specific to pathogen
In the response speed graph what does the redline show?
Red Line:
oWhat would typically happen in an individual who lacking a key part of their innate
immunity (in this case innate cells called polymorphonuclear cells or PMNs or
macrophages MAC).
o No innate
immune response to control the infection in the early stages; the amount of
MO’s increase exponentially and swiftly overwhelm the host
In the response speed graph what does the green line show?
Green Line:
oAbsence of adaptive immunity; deficient in T and B cells.
oIndividuals with innate immune cells (MAC and PMN)
oThe infection is controlled initially by the innate immune system
oEventually the infection takes hold and numbers increase compared to healthy (yellow)
as there is no adaptive response to kick in and eliminate infection.
oThese individuals will succumb to infection BUT not as quickly as those in red
Innate
In the response speed graph what does the yellow Line show?
Yellow Line:
oHealthy individuals.
oMO numbers increase slowly
oProliferation is controlled and limited by the innate immunity which can respond rapidly.
oAfter time the adaptive immune response is then activated and is able to bring about a
dramatic reduction in the MO levels, effectively eliminating them to reduce the number
to clear the infection
