Midterm Part 5

Question 1

What are the three main types of secreted antibodies?

Answer 1

IgM, IgG, IgA

Question 2

How does IgG kill pathogens? Where is it located?

Answer 2

• Neutralization, opsonization, complement activation

- bodily secretions

Question 3

Which antibody contributes to passive immunity from mother’s immune system across the placenta?

Answer 3

IgG

Question 4

What is the purpose of IgA? Where is it found?

Answer 4

bodily secretions (tears, saliva, mucus, mother’s milk, etc.). Its purpose is to bind to and neutralize pathogens

Question 5

Where is IgE found? What does it do?

Answer 5

In serum, it binds to mast cells and triggers histamine response, also gets rid of worms/parasites
- located in tissues

Question 6

How does IgM kill pathogens? Where is it located?

Answer 6

1. Neutralization
2. Complement activation
   (Opsonization happens through complement activation)
   - blood

Question 7

If the T helper cell produces IFNy, what will the antibody class switch to?

Answer 7

IgG

Question 8

What is the most appropriate response for an intracellular bacterial infection? (Cell-mediated response)

Answer 8

1. Local innate responses to contain pathogen Spread
2. Activation of adaptive immunity
   • CD4+ T helper cells
   • Effector function: cytokines to help MP activation
   (B cells are less important)

3. Ag-specific CD4+ Th cell activation
• Cytokine mediated activation of Mϕ function
• Mϕ activation
• Enhanced phagocytosis
• Destroy pathogen

Question 9

How does the dendritic cell uptake the viral peptide and display it through cross presentation?

Answer 9

DC—Phagocytosis of the viral pathogen, and displays on both MHC I and II

Question 10

What is the appropriate response for a viral pathogen?

Answer 10

Cell-mediated immunity:
- TH cells to coordinate CTLs and B cells
- CTLs to kill infected cells
Humoral immunity:
- Antibodies to neutralize and prevent 
entry

Question 11

True or False: The TCR of a thymocyte must be able to interact with an MHC protein in order for the thymocyte to escape apoptosis.

Answer 11

True

Question 12

True or false: Healthy cells present MHC without a peptide on the cell surface

Answer 12

False

Question 13

True or False: A vaccine that contains “live” virus particles will generate a CTL response and an antibody response.

Answer 13

True

Question 14

True or false: A vaccine that contains a protein isolated from a virus particle will generate a CTL response and an antibody response.

Answer 14

False

Question 15

What are the steps of an extracellular bacterial response?

Answer 15

1. Tissue damage is a danger signal to activate mast cell degranulation
2. Leads to the characteristic signs of inflammation
3. Macrophages activate by PRR recognition (phagocytic and TLRs) of bac PAMP
4. Alternative activation of complement cascade
5. Macrophages release IL-1, IL-6 and TNFa and CXCL8
6. DC phagocytosis bacteria and migrates to the lymph node to present the peptide to the T cell (could also travel through the lymph node on its own)

Question 16

What kinds of lymphocytes generate long lived memory cells?

Answer 16

B cells, T helper cells, and cytotoxic T cells

Question 17

Why is the secondary response better, faster, and bigger?

Answer 17

1. More antigen specific cells - BIGGER
2. Memory cells are easier to activate than naïve cells - FASTER
3. Memory cells have improved their ability to function (especially for
   B cells) - BETTER

Question 18

Why are effector functions increased and improved in secondary response?

Answer 18

Increased: Ab production, Th cytokines, and CTL killer function
Improved: already class switched

Question 19

Where do long lived plasma cells live?

Answer 19

In the bone marrow

Question 20

Where do long lived memory B cells live?

Answer 20

Secondary lymphoid organs

Question 21

What is active immunity?

Answer 21

The immune system is doing the work of making antibodies
•B cells and T cells are becoming activated, proliferating and differentiating
•Memory responses develop
Example: influenza infection or vaccine

Question 22

What is passive immunity?

Answer 22

• you are getting antibodies made by someone (or something) else
• your immune system has done zero work in making these antibodies
• you will not develop memory responses
• temporary - the antibodies are degraded over time

Question 23

What kind of antibody does mother’s milk have?

Answer 23

IgA

Question 24

What are polyclonal antibodies and how are they prepared?

Answer 24

• Multiple targets

* Prepared by immunising an animal (rabbit, goat) and collecting blood

Question 25

What are monoclonal antibodies and how are they prepared? What are they useful for?

Answer 25

• One target
• Prepared by fusing B cells with a cancer cell to form a hybrid cell called a “hybridoma”

Useful for:

1. Testing if someone has been exposed to an infectious agent or had a vaccine for one
2. Measuring soluble proteins (cytokines or hormones)
3. Visualizing cells and proteins they produce within tissues
4. Identifying the presence, quantity, and phenotype of different cell types
5. Treating disease

Question 26

How is ELIZA used to test if someone has antibodies against a particular agent?

Answer 26

1. Bind a known target (antigen) to the plastic
2. Add primary antibody (from hybridoma) specific for the target, incubate, then wash away
3. Add Secondary Ab, specific for the primary Ab, eg. anti-human IgG, bound to an enzyme, incubate and then wash
4. Add Substrate for the enzyme, that produces a colour

Question 27

How is ELIZA used to measure the concentration of a soluble protein in a sample?

Answer 27

1. Add known primary antibody
2. Add diluted patient serum (and a known concentration of protein as a control), incubate and wash
3. Add enzyme-linked secondary antibody, incubate and wash
4. Add coloured substrate for enzyme

Question 28

How do you used fluorescence microscopy?

Answer 28

1. Take a throat swab from a patient and rub it onto a microscope slide.
2. Fix the bacteria to the slide.
3. Soak the slide in a solution of fluorescent antibodies that recognises the bacteria.
4. Wash away unbound antibodies.
5. Place the slide on a fluorescence microscope. The microscope has a light source that emits light of the proper wavelength in order to excite the fluorescent molecule. It also has filters that allow you to see only the light emitted by the fluorescent molecules.
6. If bacteria are present, bacteria on the slide will be lit up and visible through the microscope.

Question 29

What is graft rejection? What are the two types?

Answer 29

when the recipient’s T cells mount an attack against the donor organ

1. INDIRECT ALLORECOGNITION: antigen presenting cells (APCs) from the recipient take up and process MHC proteins from the transplanted organ/tissue. The recipient T cells then recognize the presented peptide as foreign and mount a response
2. DIRECT ALLORECOGNITION: donor-derived antigen-presenting cells are able to move out of the transplanted organ and interact with the recipient’s T cells. The recipient T cells recognize the MHC proteins on these donor-derived APCs as foreign and react very strongly (independent of the peptide presented)

Question 30

What is tissue typing?

Answer 30

the process that determines the specific HLA alleles that an individual has.

Question 31

What is graft vs host disease?

Answer 31

If hematopoietic stem cells are transplanted into a recipient’s body with the allograft, the transplanted immune cells might recognize the host’s MHC as foreign and mount an immune response against the host’s cells, tissues and organs