Lecture #11 Flashcards
What is an adaptive immune response?
A specific defence that responds to an invasion of a foreign object
Does the adaptive immune system have a memory aspect?
Yes, the foreign object can be learnt so next time you won’t get sick
Is the adaptive immune system acquired naturally or artificially?
Both
How would adaptive immune system be acquired natural?
An organism or toxin enters the body and promotes immune response.
What is an example of how natural adaptive immunity is acquired?
Mother to child via placenta
How would the adaptive immune system be acquired artificially?
Can result from an immunization with a vaccine
What are two components of the adaptive immune system?
Specific and memory component
How is the adaptive immune system specific?
The immune response will only protect against one disease and does not protect against others
What is one exception for the specificness of the adaptive immune system? Give an example
When two disease are very closely related, the immune system can respond to both.
Ex. Cow pox and small pox
What is the memory component of the adaptive immune system?
The immune system will respond much stronger upon re-exposure to the virus and it serves as long term immunity (can be for life)
What are two types of responses that occur from the adaptive immune system?
- Antibody mediated response
2. Cell mediated response
What is another word for antibody mediated response?
Humoral response
How does the antibody mediated response of the adaptive immune system work?
Small molecules called antibodies or immunoglobulins bind to and inactivate foreign particles (cells, toxins, pollen,etc)
How does the cell mediated response of the adaptive immune system work?
Triggers activation of lymphocytes which recognize and destroy abnormal or infected host cells
What can lymphocytes of the cell mediated response do besides attacking cells?
Can attack bigger targets such as tumours
What is the difference between an antigen and an antibody?
Antigen- foreign particles (bad)
Antibodies- good molecules which destroy bad cells
How do we develop immunity?
The immune system recognizes an antigen and responds by:
- Producing Antibodies to the antigen
- Triggers specific killer cells
When the body produces antibodies to kill the antigen, what occurs? What is this called?
They produces antibody proteins that specifically bind and inactivate antigens
Called a humoral response
When the immune system triggers specific killing cells what occurs? What is this also called?
The killer cells destroy large antigens and abnormal infected host cells
Called mediated immune response
What is a humoral response?
What is a mediated immune response?
Humoral: when antibodies are produced to kill the antigens
Mediated immune response: triggering of specific killer cells
What is an antigen? What can it be broken into?
Antigen is a foreign particle that enters the body
Epitope is an antigen broken into smaller parts
What is the point of an epitope?
It is a particular portion of the antigen that is recognized by the antibody
What is an antibody?
A proteins produced response to an antigen or epitope
How do antibodies bind to antigens?
In a very specific manner, like a lock and key
What is another work for an antibody?
Immunoglobulins (Ig)
What are the 4 parts of an antibody
- 2 identical heavy chains
- 2 identical light chains
- 2 identical antigen binding sites
- A constant fragment (Fc)
What are the light and heavy chains in an antibody held together by?
Covalent bonds
What are the 2 binding sites on an antibody called? What is it specific for? How many antigens can it connect to?
Fab, and is specific for one epitope.
Can connect to two antigens
What does the constant fragment (Fc) on an antibody do?
Binds compliment proteins and phagocytes
What are the 5 classes of antibodies?
- Immunoglobulin G (IgG)
- Immunoglobulin M (IgM)
- Immunoglobulin A (IgA)
- Immunoglobulin D (IgD)
- Immunoglobulin E (IgE)
Which class of antibody is the most common?
Immunoglobulin G
Where is IgG found?
In blood but can also enter inflamed tissues because they are so small
Which antibody class is able to cross the placenta and pass on passive immunity to fetus?
IgG
Which antibody class binds to antigens well and is able to form clumps?
IgG
How many proteins are found in IgG?
It is a monomer so only one
How many proteins are found in IgM? How many antigens is it able to bind to?
A pentamer- with 5 antibody units allowing it to bind to 10 antigens
Where is IgM found? Attached to what?
Remains in blood (too big to get into tissue), attached to the surface of B cells
Which antibody is the first type produced upon infection?
IgM
What is IgM good at?
aggregating antigens
How many binding spots does IgA have for antigens? How many antibodies it is (what is the name for it)?
4 binding spots, two antibodies (called a dimer)
Where is IgA found? What does it protect?
In body secretions and protects mucosal surfaces
What does IgA do for newborns?
Protects the gastrointestinal tract
What does IgD do?
Unknown function
Where is IgE found?
Surface of certain immune cells such as mast cells and basophils
What do IgE do?
When it binds to an antigen, it releases histamine. This attracts compliment and phagocytes to the area
What does histamine cause?
Allergy symptoms
What are 6 functions of antibodies?
- Agglutination
- Neutralization
- Complement Activation
- Opsonization
- Antibody Dependant Cytotoxicity
- Immobilization
What is agglutination in regards to antibody function
When antigens become stuck together which allows the number of infectious units to be decreased and able to be dealt with
What is neutralization in regards to antibody function
When the antibody binds to and inactivates toxins, bacteria and viruses (bear hugging you, blocking your way)
Which function of antibodies is the first step to getting rid of a virus?
Neutralization
What is compliment activation in regards to antibodies
Antibody binds to bacteria and therefore acts as the starting point for the complement pathway (MAC attack)
What is opsonization in regards to antibody function?
Flags down the phagocytic cells to destroy the antigen
What is antibody dependant cytotoxicity in regards to antibody function?
The antibodies flag down cells of the immune system to destroy abnormal or infected body cells
What is immobilization and prevention of adherence in regards to antibody function?
Antibody binds to flagella to inhibit movement of pathogen and an antibody binds to the pili to stop adherence of pathogen
What are the cells of the adaptive immune system?
- Lymphocytes: B and T cells
- T cells: Helper T cells and Cytotoxic T cells - Antigen Presenting Cells (ABC)
What are two types of lymphocytes?
- B lymphocytes (b for bone marrow) (b cells)
2. T lymphocytes (T cells)
What do B lymphocytes do? Where are they produced?
They produce antibodies and are involved in humoral (antibody mediated) response.
Produced in bone marrow by stem cells
Where are T cells produced/matured?
Produced in bone marrow but mature in the thymus gland
What are two types of t lymphocytes (t cells)?
- Helper T cells
2. Cytotoxic T cells
What do helper t cells do?
Help B and cytotoxic T cells prepare for an immune response
What type of immune response are helper T cells part of?
Humoral (antibody) and cell mediated immunity
What type of cells do HIV viruses infect?
Helper T cells
What do cytotoxic T cells do?
The lyse (burst) foreign or abnormal host cells
What type of response are the cytotoxic T cells apart of?
Cell mediated immune response
What are 3 types of cells that are antigen presenting cells?
Macrophages, B cells and Dendritic cells
What cells produce antibodies?
Red and White blood cells
What do antigen presenting cells do?
Patrol around and look for antigen that shouldn’t be found inside the tissue
What is the first stage of antigen presenting cells?
Foreign material such as bacterial cell is engulfed by the antigen presenting cell
What is the second stage of the antigen presenting cell?
The antigen is processed and presented to T helper cells of the immune system as well as self antigens
What are self antigens part of (what complex)?
The major histocompatibility complex
Why are antigens found by the antigen presenting cells taken to both T helper cells and self antigens?
To check them to prevent the destruction of our own cells by mistake
What is the 3rd stage of antigen presenting cells?
T helper cells become activated against foreign material
Where are MHC 1 receptors found? MHC 2?
MHC 1: surface of every cell with a nucleus
MHC 2: only on antigen presenting cells
What does it mean when an antigen is endogenous
Originates inside the compromised cell
What does it mean when an antigen is exogenous?
Brings the antigen into cell, breaks it into pieces and chooses to take up the exogenous antigen
What are the 4 stages of antibody production?
- Antigen enters body
- A t helper cell binds to it and presents b cells after recognizing the antigen bound to the MHC protein
- T helper cells deliver cytokines that stimulate the B cells
- Clonial expansion occurs
Which type of cells have MHC1 or 2 receptors on them?
APC (macrophages, B cells and dendritic cells)
Which type of cells have CD4 or CD8 on them?
T helper cells and Cytotoxic t cells
During antibody production, when the antigen enters the body, what happens?
- Antigen is phagocytize and destroyed by the B cells
2. Small fragments of the antigen will be presented on the surface of B cell along with MHC
What occurs when, during antibody production, the B cell are stimulated?
The B cell multiplies and divides producing more identical B cells that will then fight off the specific antigen
When clonial expansion happens during the production of an antigen, what can the B cells divide and differentiate into?
Either plasma cells or memory cells
What are the characteristics of plasma cells?
- Produce antibodies
- short lifespan
- produce many antibodies
How long do memory cells live? Where are they found?
Live long (20-30 years) Circulate in the blood
What do memory cells do when they discover an antigen?
Quickly changes, multiplies and becomes an antibody producing plasma
What is a primary response vs a secondary response in regards to the adaptive immune system?
Primary: response that occurs the first time the body encounters an antigen
Secondary: response that occurs every time after the primary encounter
What occurs during a primary response of the adaptive immune system?
The antigen stimulates production of low levels of antibodies (5-7 days).
IgM is made first then IgG and IgA
The final product is memory built for the antigen
What occurs during the secondary response of the adaptive immune system?
High levels of antibody are produced (1-2 days, quick) and therefore the infection is quickly overcome, afterward memory cells are replenished
When is cell mediated immune response activated?
By invading cells or abnormal host cells
What cells are involved in a cell mediated immune response?
APC’s, T helper cells and cytotoxic T cells
What are the 3 stages of cell mediated immune response?
- Recognition of Abnormal host cells
- Endogenous Antigens processed and displayed on cell surface
- Perforins and Granzymes
What cells are considered abnormal when talking about cell mediated immune response?
- virus infected cells,
- bacteria infected cells
- cancer cells
- foreign cells (blood transfusion or bone marrow transplant)
When T cells recognize abnormal host cells during cell mediated immune response, what happens?
A dendritic cell engulfs foreign antigen and presents it to a specific cytotoxic cell. Memory T cells and Cytotoxic T lymphocytes then are produced
During step two of cell mediated immune response, what happens?
Endogenous antigen is processed and displayed on cell surface of antigen presenting cells with MHC1 self antigen
What occurs in the Perforins and Granzymes step of cell mediated immune response?
Perforins and Granzymes are released from the cytotoxic T cell.
Perforins poke holes in cell membrane of abnormal cells
Granzymes cause infected cell to undergo apoptosis
What is apoptosis
Programmed cell death
What is active immunization?
The body goes through the complete process to generate specific antibody or cytotoxic T cells
Is active immunization natural or artificial?
Can be either
What is natural immunization? Artificial?
Natural- When the antigen is encountered from the environment
Artificial- when the antigen is injected as a vaccine
What is passive immunization? What is the downfall?
Being given the ready made antibody.
Downfall is it does not result in long lasting immunity
Is passive immunity natural or artificial?
Both
What is an example of natural passive immunization?
From mother to infant.
IgG is transferred from mother to fetus via placenta
IgA is transferred from mother to child via milk
What is artificial passive immunization? Give an example
Pre-made antibody injected for when in need of fast acting.
Ex. life threatening situations such as snake venom- an antitoxin antibody is given
