Topic 6.7 Response To Infection Flashcards
What does innate mean
Non-specific
What are three main ways pathogens can enter our tissues?
Via our
- skin
- lungs
- intestines
How does the skin protect the body against pathogens?
- sebum contains fatty acids, toxic to microbes
- keratin stops bacterial growth
How do lungs / respiratory system protect the body against pathogens?
- mucus made by goblet cells : trap pathogens/microorganisms (bcs sticky)
- cilia, woft mucus, either spat out or destroy in stomach
What is the non-specific inflammatory response?
- innate, same response whatever the pathogen
- localised response of tissues to damage
1. Triggered when mast cells release histamine and prostaglandins - histamine causes dilation of venules or arterioles,diapedesis
- more tissue fluids (with phagocytes) go towards injured site, so phagocytes can engulf
- prostaglandins increase blood flow
2. Sensory neurons become more sensitive
Why is prostaglandins useful in the inflammatory response?
Increase blood pressure and flow
So more tissue fluids (including phagocytes) coming to the area
What is diapedesis?
capillaries become more permeable
What is an erythrocyte
Red blood cell
How do you know it’s a neutrophil?
It has a multi-lobe nucleus
What shape nucleus do macrophages have
Kidney shaped
What do lymphocytes usually look like (their nucleus shape)
Round nucleus
2 types of phagocytes
Neutrophils
Macrophages
What’s the difference between neutrophils and macrophages?
- N come out of capillaries, engulf pathogens
- N dominate infected simple early / M at later stages
- M does that, and adds another step
- live longer , larger
- can present antigenic fragments to T lymphocytes after engulfing
- N has multi-lobe nucleus / M is big and kidney shaped nucleus
What is MHC
Proteins every cell has them - markers
Diff tissues have varying MHCs
Help cells identify it’s a self cell, not foreign (so won’t attack)
What’s an antigen presenting cell
Antigen fragments bounded to MHC
What are cytokines
Cell signaling protein to recruit other cells
What does chemokines do
Induce chemotaxis
Recruit other phagocytes (macrophages)
What are the 2 types of lymphocytes
B or T
What do B and T lymphocytes have
Antigen-receptor molecules
Complementary to antigens
Each lymphocyte has only 1 type of antigen receptor (unique to cell types)
What is the difference between B and T lymphocytes?
B can release antigen receptor (aka antibodies) (also stays, does both) (become plasma cells)
T cannot, they only stay on cell
What is the humoral response 1?
- macrophage and B lymphocytes engulf pathogen
- present their antigens on MHC to become APCs
- T helpers activated when binding with macrophage antigen-MHC complex, producing more T helpers and memory
- more T helpers bind with B-lymphs, secrete cytokines and activate
- mitose and produce B effector cells > differentiate into either B memory or plasma
How do intestines / digestive system protect the body against pathogens?
- stomach acids
- enzymes found in saliva, lysozymes
- gut microbiomes (flora) outcompete pathogens
What does histamine do?
histamine causes dilation of venules or arterioles: diapedesis (capillaries become more permeable)
more tissue fluids (with phagocytes) go towards injured site, so phagocytes can engulf
What do prostaglandins do?
Increase blood flow to injured site
Why would prostaglandins cause oedema?
Because more tissue fluids are transported (?) to the injured site
trigger the inflammatory response, causing blood vessels to leak fluid into the tissues
What are 2 things that mast cells release?
- histamines
- prostaglandins
What are 2 types of phagocytes?
Macrophages and neutrophils
What turns into an Antigen presenting cell (APC) in humoral 1?
Macrophages and B-cell
What can release antigen receptors
B lymphocytes
What activates the B cell in humoral 1?
T helper cells using cytokines
What happens with B cells after activation with T cells
Divide (via mitosis)
Into B-memory cells
OR effector cells that further differentiate into plasma cells, that can release antigen receptors
What does MHC stand for and made of?
Major Histocompatibility Complex
Glycoproteins within phospholipids bilayer, highly variable
What are complement proteins? What do they do?
In plasma, activated by presence of pathogens
Happens at the same time as phagocytosis happens (before humoral, during inflammation)
- attract more phagocytes (like cytokines)
- opsonins binds to surface of membrane of foreign cells, water enters pores via osmosis, lyse
- aid attachment of phagocytes
What is the process of phagocytosis? (4 steps)
- phagocytes are attracted to chemicals produced by pathogens (chemotaxis)
- Receptors on phagocyte membrane attach to pathogen
- phagocyte engulfs pathogen in vesicle (phagosome)
- lysosome fuses w phagosome = phagolysosome
- release hydrolytic enzymes to digest pathogen
Where are B and T lymphocytes made and mature?
B- made, stay and mature in bone marrows (B-B)
T- made in bone marrows, mature in Thymus (T-T)
Can T lymphocytes bind directly to pathogens?
No
Can only bind to antigen presenting cells (APCs)
What’s the point of antibodies? (4)
- enhance phagocytosis (opsonisation)
- activate more complement proteins (so more lysis)
- can bind to toxins and neutralise them
- reduces number of infectious units to be dealt with (Agglutination) (GLUE things tgt)
What are 2 types of toxins by bacteria
Endotoxin
and exotoxin
What’s opsonisation
Enhance phagocytosis
What is humor in humoral?
Body fluids
Since Antibodies released to body fluids
B lymphocytes only involved
Humoral response cannot take place when…
Virus has already injected itself into host cell
Change in MHC of a self cell is considered a ….
How does it happen
An APC
Due to mutation or replicating antigens in protein synthesis (?)
What does T lymphocytes divide into in cell mediated immune response?
T killer (cytotoxic cell)
T memory
More t helper
What are T helper cell receptors called
CD4 receptors
What is the cell mediated immune response?
When pathogens are inside host cells , antibodies aren’t effective
T-helper cells bind to APC and become activated + release cytokines
Divide into 3 types of cells (T-killer, T-helper, T-memory)
How do T-killer cells destroy body cells infected by viruses (APC)?
Destroy cells changed by mutation to form cancer cells or cells transplanted organ using perforin
Unnecessary usage of antibiotics is a …
A selection pressure
Explain why agglutination could take longer at low and at high concentrations of sperm cells? (2 marks)
- Bcs at low conc the collision between antibody and antigen is less frequent
- bcs at high concs there may be insufficient antibodies
If mention of antibodies, immediately think…
Humoral response
Compare and contrast cell mediated vs humoral response
- both use T cells
- both produce memory cells
- both involve cytokines
- both are ACTIVE forms of immunity
- T killer involved in cell mediated / not h
- antibodies invoked in H / not c
- antigen presentation in H by B cells / infected host cell present antigens in C (only when host cell is infected)
Why are cytokines released in cell mediated response?
To recruit T killer cells
How are monoclonal antibodies made?
- inject antigen into mouse
- trigger humoral response of mouse
- extract plasma cells (that release complementary antibodies)
- fuse with myeloma cells
- hybridoma cells produced > divide and secrete antibodies
- purify antibodies
What are uses of monoclonal antibodies?
- cancer treatments
- vaccine
- tests (covid, pregnancy)
- identify cancerous cells or blood clots (PET scans)
What are the issues with using monoclonal antibodies made by mice plasma cells (B-lymphocytes)?
- foreign proteins to humans (attack w humoral!)
What is humanising antibodies and why is it beneficial?
Put specific antigen binding sites of mice onto human antibodies
- less foreign so less likely to reject
- complementary to target antigens so only attached to them
- have less side effects
What is monoclonal antibody therapy?
Using monoclonal antibodies (mAb) to bind to specific cells or proteins
Stimulate patients’ immune system to attack those cells
What can you put in vaccines?
- antigens
- inactivated pathogens
- antibodies
- mRNA (so protein synthesis, produce antigen after cell mediated response, present antigen on MHC, host cell becoming APC)
Outline the process of cell mediated response.
- complementary T helper lymphocytes bind to foreign antigen on APC
- rapid mitosis takes place, become memory cells or trigger humoral
- T killer cells produced, secrete perforin to destroy infected cells
What are antibodies?
Proteins secreted by plasma cells
complementary Antigen receptors
Types of vaccine?
- inactivated pathogens
- live attenuated (chemically modified, so doesn’t cause disease)
- toxoids (modified toxins)
- genetically modified DNA/mRNA
- administered either by injection or orally
Why is genetically modified DNA/mRNA vaccines trigger cell mediated response, not humoral?
Because it has DNA and mRNA has to be transcribed and reached host cell
Cell mediated tackles host cells that have been injected by pathogens
What response is specific
Humoral
Cell mediated
What response is nonspecific?
Inflammatory
how does a macrophage become an antigen presenting cell? (2 marks)
- binding of antigen to receptor on T helper cell
- antigen presented surface of MHC of macrophage
EDIT: DOESNT MAKE SENSE???
what is the definition of immunity?
ability of the body to protect from infection and disease
what is the definition of pathogen? and what could they be?
a microorganism that causes disease
-virus/bacteria/protist/fungus
what is the definition of infection?
where pathogens have invaded the body cells or tissues
what is the definition of antigen? what could they be made of?
a glycoprotein/protein/polysaccharide
often found on outside of a cell that triggers an immune response
what are the 2 types of non specific immune responses?
phagocytosis
inflammatory
what are the 2 types of specific immune responses?
- humoral
- cell mediated
what do lysosymes do?
destroy bacteria by hydrolysing the peptidoglycan in their cell walls
what is phagocytosis?
engulfing pathogen (followed by digestion)
binding of pathogen/antigen to phagocytic cell
and engulfing in a vesicle (phagosome)
where are phagosomes made?
cell surface membrane of phagocytic cell
Myeloma cells have the potential to divide indefinitely.
Explain why myeloma cells are used in the production of monoclonal antibodies. (2 marks)
- to produce genetically identical hybridoma cells
- lots of antibodies produced
- so hybridoma cells can divide
Explain the advantages of using humanised antibodies in the treatment of cancer. (3 marks)
- prevent triggering immune response
- less side effects
- targets specific cells (complementary only)
Zika is not a retrovirus.
Describe what happens to the Zika RNA once it is in the cell. (2 marks)
- used for translation to make viral proteins
- more RNA produced
Describe how macrophage presents the antigens to T helper cells. (2 marks)
- antigen on surface / MHC of macrophage
- binds to CD4 receptor on T helper cells
