Unit 8 Assignments Flashcards
Innate vs Adaptive
Adaptive immunity: A specific immune response that develops over time, targeting particular pathogens and involving memory for faster future responses.
Innate immunity: A non-specific, immediate defense mechanism against pathogens that does not require prior exposure.
Determine whether each scenario is MOST LIKELY an example of innate or adaptive
Vaccinating against measles
Adaptive - Builds memory
Determine whether each scenario is MOST LIKELY an example of innate or adaptive
You get something in your eye and you immediately start tearing.
Innate - Immediate response
Determine whether each scenario is MOST LIKELY an example of innate or adaptive
Coughing
Innate - Reflex to expel pathogens
Determine whether each scenario is MOST LIKELY an example of innate or adaptive
You are sick with flu-like symptoms & your doctor does some blood work to determine what type of infection you have. The blood work comes back and your IgG levels are high
Adaptive - Specific immune response
Determine whether each scenario is MOST LIKELY an example of innate or adaptive
Complement proteins are at work
Innate - Enhances defense
Determine whether each scenario is MOST LIKELY an example of innate or adaptive
Commensal Staphylococcus aureus is cultured from your skin swab when doing a ubiquity experiment in lab. You lab partner asks why you aren’t sick
Innate - Microbiota protection
Determine whether each scenario is MOST LIKELY an example of innate or adaptive
You accidentally get exposed to a patient’s blood through a cut on your hand. Your blood work comes back positive for Hepatitis B antibodies
Adaptive - Immunological memory
Determine whether each scenario is MOST LIKELY an example of innate or adaptive
Your punctured finger is red, swollen and painful
Innate - Inflammatory response
Determine whether each scenario is MOST LIKELY an example of innate or adaptive
Temperature of a 103 degrees Fahrenheit
Innate - Fever to hinder pathogens
Determine whether each scenario is MOST LIKELY an example of innate or adaptive
B lymphocytes and T lymphocytes are at work
Adaptive - Specific immune cells
What are the 2 categories of the Adaptive (specific) immune response?
- Humoral immunity
- Cell-mediated immunity
What does a humoral immune response consist of?
The activity of B-cells and the antibodies they produce
Which part of the adaptive immune response involves B cells?
Humoral
Antibodies are a part of which type of immunity?
Humoral
What are antigen-presenting cells?
Certain type of phagocytic cells of the immune system that seek out foreign cells and engulf them
What is antigen processing and presentation?
A way for a cell to display information about its activities
Ex. The phagocyte in antigen-presenting cells needs to show what they captured
The virus in the infected cell needs to show that it is infected
Why would a body cell that is not a phagocyte need to present antigens?
Non-phagocytic body cells can become infected with a virus
How do phagocytes communicate to other cells what they have captured?
They present antigens from engulfed foreign cells
What are some examples of antigen-presenting cells?
- Macrophages
- Dendritic cells
Antigen-presenting cells have _________ that are used to present antigens on their surfaces
Collectively these ________ are called _______ which stands for ________________________
Antigen-presenting cells have two classes of special proteins that are used to present antigens on their surfaces
Collectively these proteins are called MHC which stands for Major histocompatibility complex
What are the different types of Classes of MHC proteins
- Class I MHC proteins
- Class II MHC proteins
What are Class I MHC proteins?
Proteins used to present antigens produced within the cell
What are Class II MHC proteins?
Proteins used to present antigens engulfed by antigen presenting cells
Most of the other cells in the body including __________ are also able to ____________
However these cells only have the ______
Most of the other cells in the body including infected cells are also able to present antigens
However these cells only have the Class I MHC proteins
Which structure do antigen presenting cells utilize to directly help them present bacterial antigens?
Phagolysosome;
to break down bacterial components
Which of the following are likely to be found on an MHC-I protein?
- Bacterial cell wall fragment
- Bacterial DNA
- Damaged mitochondrial fragment
- Membranes from a neighboring dead host cell
- Bacterial flagella
- Damaged mitochondrial fragment;
MHC-I proteins present endogenous antigens, typically fragments derived from within the cell, such as:
- damaged mitochondrial fragments
- or viral proteins produced in infected cells
What is likely to be found on an MHC-I protein?
Bacterial components like:
- cell wall fragments
- DNA
- or flagella
by antigen-presenting cells
What would a virally infected skin epithelial cell have on its cell surface?
- Class II MHC with liver cell antigens
- Class I MHC with skin cell antigens
- Class II MHC with macrophage antigens
- Class II MHC with viral antigens
- Class I MHC with skin cell antigens
Antigens associated with ________ proteins originate from within the __________.
Antigens associated with Class I MHC proteins originate from within the host cell.
Which of the following would you likely see on the surface of a human dendritic cell following phagocytosis of a bacterium?
- Class II MHC with dendritic cell antigens
- Class II MHC with engulfed bacterial antigens
- Class I MHC with dendritic cell antigens and Class II MHC with engulfed bacteria
- Class I MHC with dendritic cell antigens
- Class I MHC with dendritic cell antigens and Class II MHC with engulfed bacteria
Tom has a genetic disorder in which he does not synthesize class I MHC proteins or functional NK cells. Which of the following statements would be true for Tom?
- Tom would not be able to destroy virally-infected cells.
- Tom would be more susceptible to bacterial infections.
- Tom would not be able to produce antibodies against viruses.
- Tom would be less susceptible to helminth infections.
Tom would not be able to destroy virally-infected cells;
Class I MHC proteins are critical for presenting viral antigens to cytotoxic T cells, which destroy infected cells. Without Class I MHC or functional natural killer (NK) cells (which can kill cells lacking MHC I), Tom’s immune system cannot effectively eliminate virally infected cells.
MHC proteins are used to present _____ on the surface of the cell
MHC proteins are used to present peptides on the surface of the cell
_________ enter the _______________ and are loaded onto ______ proteins
The vesicles containing the ___________ complexes bud off of the ______________ and are released into the __________
Vesicles containing these complexes travel through the _______ to the ______________ delivering the complexes to the exterior of the cell
Peptides enter the endoplasmic reticulum and are loaded onto MHC proteins
The vesicles containing the MHC-peptide complexes bud off of the endoplasmic reticulum and are released into the cytosol
Vesicles containing these complexes travel through the cytosol to the cytoplasmic membrane delivering the complexes to the exterior of the cell
Where are MHC molecules located on a cell?
On the surface of the cell
What is a feature of the small fragments presented by MHC-I proteins?
They are small peptides, roughly 8-10 amino acids long.
Which organelle assists directly with the presentation of MHC-I antigens?
The endoplasmic reticulum
When does MHC-II loading occur?
- During phagocytosis of an invading pathogen
- After passing through the endoplasmic reticulum
- During the fusion of vesicles containing MHC-II proteins with vesicles containing digested pathogens
- During viral infection
- During the fusion of vesicles containing MHC-II proteins with vesicles containing digested pathogens
Which of the cells listed below can present antigens on Class II MHC proteins?
- Virus infected epithelial cells
- Healthy epithelial cells
- Tumor cells
- Macrophages
- Macrophages
At lease how many antigen-binding sites does each antibody have?
2;
allowing antibodies to bind to more than one microbial cell resulting in agglutination or clumping
How does agglutination by antibodies help the body?
It helps remove microorganisms from the body
Antibodies can neutralize ____, _______, & ______
By binding to _______________________ or blocking proteins necessary for _____________
Antibodies can neutralize toxins, viruses, & Bacteria
By binding to critical portions of the toxin or blocking proteins necessary for attachment to cells
Antibodies also act as ________ for phagocytosis and activate the ____________ system.
Antibodies also act as opsonins for phagocytosis and activate the complement system.
What makes agglutination by antibodies possible?
Each antibody has at least two antigen-binding sites
What is the role of plasma cells in humoral immunity?
Plasma cells produce antibodies
Which of the following most accurately describes how a pathogenic bacterium might be affected by antibodies?
- The antibodies may block proteins necessary for binding the pathogen to the host.
- The antibodies may coat the surface of the bacteria (opsonization), allowing for it to be tagged for phagocytosis.
- The antibodies may stick to multiple bacteria, causing agglutination.
- The antibodies may block proteins necessary for binding the pathogen to the host, may opsonize the bacterium, or may agglutinate bacteria.
- The antibodies may block proteins necessary for binding the pathogen to the host, may opsonize the bacterium, or may agglutinate bacteria;
Antibodies can have multiple effects on pathogenic bacteria they can:
- block adhesion to host cells (neutralization)
- mark the bacteria for phagocytosis (opsonization)
- and cause bacteria to clump together (agglutination)
all of which help the immune system eliminate the pathogen.
Each helper T-cell produces a unique _____________________ which corresponds to a specific antigen
Each helper T-cell produces a unique T-cell receptor (TCR) which corresponds to a specific antigen
What is a receptor that each helper T-cell displays on its surface?
CD4;
which recognizes the MHC molecules of antigen-presenting cells
When the helper T-cell encounters and antigen-presenting cell with an antigen displayed in a MHC molecule, it signals the antigen-presenting cell to release what?
Interleukin-1 ;
The IL-1 stimulates the helper T-cell to produce IL-2 as well as IL-2 receptors
After IL-2 and IL-2 receptors are produced the helper T-cell can then autostimulate itself __________
keeping it active as it proliferates (rapidly increase in number and grow)
Once a helper T-cell becomes activated what happens?
It proliferates, forming a clone of cells specific to the same antigen
Some of these helper T-cells differentiate into long lived memory T-cells but most mature to produce cytokines to help with the immune response
What are the two subpopulations that the helper T-cells differentiate into?
TH1 cells : produce cytokines that activate the cells of cell-mediated immunity (cytotoxic T cells, macrophages, NK cells)
TH2 cells: produce cytokines that activate the B-cells involved in humoral immunity
Which receptor on the helper T-cell recognizes the specific antigen from an antigen-presenting cell?
TCR (T-cell receptor)
TH2 cells produce cytokines that activate what?
B-cells
Which proteins on the antigen-presenting cell are recognized by the helper T-cell?
MHC; Class II proteins
When do helper T-cells develop into TH1 or TH2 cells?
After proliferation into a clonal population
Natural killer cells are activated by what?
TH1 cells
What is clonal selection?
The process of B-cell activation;
a B-cells with a specific antigen receptor recognizes an antigen
this cell proliferates to produce a multitude of cells (clone of cells)
differentiate into memory B-cells and plasma cells
What is clonal expansion?
When the cell proliferates to produce a multitude of cells (called clone of cells)
and differentiates into memory B-cells and plasma cells
The antibodies produced by the plasma cells bind to antigens to produce the _________ response
The antibodies produced by the plasma cells bind to antigens to produce the humoral response
antibodies IgM
IgG
In the simplest form of B-cell activation, and antigen called a ______________ antigen enters the _______________ and binds to a B-cell receptor (BCR) on the surface of the B-cell
In the simplest form of B-cell activation, and antigen called a T-independent antigen enters the lymphatic tissue and binds to a B-cell receptor (BCR) on the surface of the B-cell
The BCR on a particular B-cell are _______ and very specific to ________ antigen(s)
The BCR on a particular B-cell are identical and very specific to just one antigen
Once the BCR binds to the _____________ antigen, the B-cells becomes ________ and is _____________
Once the BCR binds to the T-independent antigen, the B-cells becomes activated and is now ready to proliferate
B-cell is now ready to proliferate, however most antigens are not potent enough to activate B-cells by themselves.
In these cases what will the B-cell require?
In these cases the B-cell will require a second opinion form a helper T-cell to become activated by releasing cytokines
These antigens are called T-dependent antigens
After a B-cell proliferates or divides what do the B-cells differentiate into?
- Some become long- lived Memory B-cells
- Most become plasma cells which secrete antibodies against the antigen that activated them
These antibodies can enter the bloodstream and travel throughout the body
Plasma cells live for ________________ but each one can produce about _______ antibodies every second
Plasma cells live for only a few days but each one can produce about 2000 antibodies every second
What best characterizes clonal selection?
The production of identical B cells producing the same antibody
What is produced by the process of clonal expansion?
Plasma cells & memory B cells
An antigen that is potent enough to activate a B cell on its own is known as?
T-independent antigens
Based on the animation, T cells recognized the antigen displayed by what protein of the B cell?
MHC protein
How can a sufficient humoral immune response occur if a plasma cell only lives for a few days?
Each plasma cell can produce up to 2000 antibodies every second
After the first exposure to an antigen there is a ______ in which the exposed person’s ________ does not contain any detectable antibodies
After the first exposure to an antigen there is a lag period in which the exposed person’s serum does not contain any detectable antibodies
The primary immune response involves:
When after several days of being exposed to an antigen the concentration of antibodies slowly rises, followed by a gradual decline
For approximately how many days is IgG present in the serum?
10 days
On what day does IgM first appear?
Day 5
What is the secondary immune response?
aka, memory response or anamnestic response
When after the B-cells differentiate into long lived memory cells if they become stimulated by the original antigen, even years later, they rapidly produce antibody-secreting plasma cells
Faster and stronger response
Which cells are involved in a secondary response?
Memory B cells and plasma cells
How is the secondary response different from the primary response in terms of antibody concentration in the blood?
The secondary response is faster and produces more antibodies than the primary response
On which day does the production of IgG occur in the secondary response?
Day 5
An anamnestic response is another name for what?
Secondary response
In regard to antibody function, identify the MISMATCHED pair.
- opsonization = simulates phagocytosis
- antibody-dependent cell-mediated cytotoxicity = target cell dies by apoptosis
- neutralization = covering a critical portion of a toxin so that it is no longer harmful
- agglutination = antibodies bind microbes to the vessel walls inhibiting spread of the microbe
- agglutination = antibodies bind microbes to the vessel walls inhibiting spread of the microbe;
Agglutination causes soluble molecules to become insoluble, which may target them for phagocytosis or filtering by the kidneys.
When a cytotoxic T cell encounters an infected cell with a specific antigen bound in an MHC molecule, it produces receptors for what?
IL-2;
and other cytokines such as gamma interferon, IFN-y (gamma)
Cytotoxic T- cell can be activated by what?
Cytokines from activated helper T cells
What is one pathway cytotoxic T cells can destroy infected cells?
Perforin-granzyme cytotoxic pathway:
T cells secretes 2 kinds of protein molecules: perforin and granzyme
What do perforin and granzyme do?
Perforin: forms a pore in the membrane of the target cell allowing granzyme to enter the cell
Granzyme: activates the enzymes inside the cell leading to programmed apoptosis (cell death)
What is apoptosis?
The process of programmed cell death
What is the function of the CD8 receptor?
Bind to MHC molecules
What is the fate of activated cytotoxic T-cells?
They proliferate into a clone of cells specific to the same antigen
Some of these cells then differentiate into long-lived memory T-cells
While others mature to attack infected cells
Which molecule triggers apoptosis?
Granzyme
Which event happens first during cytotoxic T-cell activation?
CD8 binds to MHC molecules of infected cells
