6.3 - Types of Immunity: Innate & Acquired Flashcards
When does an immune response take over?
When pathogens overcome the defence system of the body
List the steps of an immune response
- Detect and identify foreign substance
- Communicate with other immune cells
- Recruit help and co-ordinate response
- Destroy/suppress invader
List the 2 types of chemical signalling used by the immune system
- Antibodies (Ab) bind to antigen (Ag)
Cytokines
- affect growth or activity of other cells
What are the 2 main categories of immunity?
innate and acquired immunity
How does response time and specificity differ for innate and acquired immunity?
Innate
- more rapid, non-specific
Acquired
- slower, specific
TRUE OR FALSE
Innate responses can eventually lead to acquired responses
TRUE
Innate immunity is present _____ the pathogen is encountered
before
Once a pathogen is encountered, innate immunity responds within _____
minutes to hours
TRUE OR FALSE
Innate immunity remembers past infections and acquired immunity does not remember past infections
FALSE
Innate: DOES NOT remember
Acquired: remembers
All organisms have the ______ immunity
Innate
TRUE OR FALSE
An inflammation is distinctive in an acquired immune response
FALSE
inflammation = innate immunity
An acquired immune response takes ____
days to weeks: SLOW
Acquired immunity can be further subdivided into ?
cell-mediated immunity
humoral immunity (antibodies)
TRUE OR FALSE
Acquired immunity is only found in vertebrates
TRUE
What are the 2 lines of defences of the innate immune system?
1st line of defence
- physical and chemical barriers
2nd line of defence
- patrolling or stationary leukocytes and blood proteins
Why is the 1st line of defence of the innate immune system the most vulnerable?
Due to the thin epithelium exposed to outside env
The majority of innate immune system cells are ____
phagocytes
Innate immune system cells attract other immune cells by secreting cytokines. What are these called? Give some examples.
chemotaxins
- cytokines (chemokines) and other immune blood proteins
- products of tissue injury (e.g. fibrin)
- bacterial products
How do phagocytes leave the circulation and enter tissue through capillary walls?
squeeze in between endothelial cells in capillary linings
Phagocytes identify the invader by __
chemical cues that interact with receptors on the phagocytes membrane
TRUE OR FALSE
Phagocytes can only ingest organic material
FALSE
BOTH organic and inorganic
What’s opsonization?
tagging a pathogen for destruction
A protein that can opsonize is called a _____
opsonin
What happens when some pathogens do not have surface features that can be identified by phagocytes?
Blood proteins bind to the pathogen to tag it
phagocytes have receptors for blood proteins
What is a phagolysosome?
a pathogen that is ingested and fused with lysosomes and digestive enzymes and chemicals that kill it
What is pus?
dead phagocytes, tissue fluids, and debris collected at the site of injury
What are natural killer cells (NK) ?
Lymphocytes associated with innate immunity but have adaptive responses (specific pathogens)
How long do NK cells take to act?
within minutes
TRUE OR FALSE
NK cells have specific receptors like B and T cells
FALSE
How do NK cells kill?
- bring apoptosis in pathogen infected cells
- attack tumour cells
NK cells also produce important cytokines. List and describe their features
interferons
- interfere with viral replication
IFN A and B = induce antiviral state in nearby cells to prevent viral replication
IFN Y = activate macrophages and other immune cells
What is the role of chemical mediators in innate immune response?
to create the inflammatory response
- red warm swelling in skin
- signals other cells and agents to the site
- increase capillary permeability and causes fever
- physical barier to prevent spread of pathogen
- promotes tissue repair
What is the cytokine released to create an inflammatory response?
interleukin-1 (IL-1)
What are the functions of IL-1?
- act on endothelial cells lining blood vessels, loosens junctions between cells
- act on liver cells to produce blood proteins involved in damage control
- induce fever
- stimulate cytokine production
What is the MAC attack and what causes it?
MAC = membrane attack complex
caused by complement proteins that make holes in pathogen membranes to allow ions and water to enter, causing pathogen to swell and lyse
What are complement proteins? Give some examples
collective term for over 25 blood proteins that are activated by sequential proteolysis
e.g. opsonins, chemotaxins
Acquired immunity is also called ____
adaptive or specific immunity
What are involved in acquired immunity?
lymphocytes and lymphocytes products
What are the 3 types of lymphocytes found in the body?
Natural Killer Cells (NK)
B cells
- activated form is the plasma cell
T cells
- TC and TH
Which cells can expand clonally?
T cells and B cells
What is specificity?
individual cells recognizing different specific pathogens
What are naive cells?
cells that never encountered specific pathogen before
What happens to naive cells once they encounter a pathogen?
expand clonally, lots of effector cells
What are plasma cells? What do they do?
Mature B cells
produce a lot of antibodies (around 2000 Abs per second)
What is the difference between primary and secondary Ab responses?
primary:
- slower response and less Ab [ ]
secondary:
- faster response 24-48 hours to match primary response
- mediated by memory cells
- more Ab [ ]
How do vaccinations work?
- patient given inactivated pathogen
- generate memory cells to recognize natural pathogen
List and define the 5 classes of immunoglobins in humans
IgM
- produced during primary responses
- activates complement
IgA
- found in secretion
- neutralizes pathogens before entry
- e.g. saliva, tears
IgD
- found on surface of B cells with IgM
- unknown function
IgG
- makes up 75% plasma Ab
- secondary response Ab
- activates complement, opsonizes
IgE
- allergic responses
- recognized by mast cells
What are some important features of the structure of an antibody?
- 4 polypeptides, Y shaped
- identical sides, 2 light and heavy chains
- arms (Fab) contain the antigen binding site
- stem (Fc) determines Ab class
TRUE OR FALSE:
Antibodies are most effective to intracellular pathogens
FALSE
Extracellular pathogens
What are the functions of antibodies?
- act as opsonins to tag Ag for phagocytosis
- cause Ag/pathogen clumping
- neutralize bacterial toxins
- activate complement
- activate B cells
- activate Ab dependent cellular activity (e.g. NK cells or eosinophils)
- activates mast cells to degranulate
Where do B cells have antibodies?
on their surface as receptors (up to 100,000) that can bind to Ag directly
TRUE OR FALSE
T cells learn to recognize self MHC proteins in the bone marrow
false
IN THE THYMUS
TRUE OR FALSE
T cells can bind to free Ag
FALSE
can only bind to Ags bound to class 1 or 2 MHC
