1. After this class, you should be able to:
Tuesday February 21st, 2017
Class 28 Learning Goals
Innate Immunity
After this class, you should be able to:
Describe the relative importance of the different parts of the innate immune system in terms of the number and types of infections prevented
Predict the overall health effect of mutations in innate immune cells
Define and identify an epitope
Explain how a single group of cells can all have the same initial DNA…but then create a huge random diversity in the shape of a single type of protein

2. What % of pathogens are stopped by passive barriers?
Eyes
Blinking wipes tears across
the eye. Tears contain the
antibacterial enzyme lysozyme.
Ears
Hairs and ear wax trap
pathogens in the passageway
of the external ear.
Nose
The nasal passages are lined
with mucus secretions and
hairs that trap pathogens.
Digestive tract
Pathogens are trapped in saliva
and mucus, then swallowed.
Most are destroyed by the low
pH of the stomach.
Answer: 5
Airways (lining of trachea)
Instead of reaching the
lungs, most pathogens are
trapped in mucus and swept
up and out of the airway by
the cilia.
Ciliated
cells
Mucus-secreting
cells

3. 1) How do platelets in the bloodstream limit infection?
Peer Instruction
1) How do platelets in the bloodstream limit infection?
Blood vessel
Red blood cell
Platelet

4. 1) Neutrophils and macrophages help to stop infections. How?
Peer Instruction
Granules contain
pathogen-killing
molecules
Neutrophils arrive,
begin removing
pathogens by
phagocytosis.
Some newly arrived leukocytes
mature into macrophages
Pseudopodia engulf
bacteria
Lysosomes
digest
bacteria
Macrophage
Initiate tissue
repair
Vesicles secrete recruiting and fever signals

5. 1) How do mast cells signaling help to fight infections?
Peer Instruction
1) How do mast cells signaling help to fight infections?
Mast cells at the site secrete signaling molecules that:
-constrict blood vessel at wound
-dilate blood vessels near wound
Granules contain signaling molecules
Nucleus
Mast cell
2) How can the same signal cause two different responses?

6. 1) Will organisms with only innate immune systems live long?
Peer Instruction
Pathogens stopped by mucous membranes
Pathogens stopped by physical barriers
Pathogens stopped by innate immune cells
Internal pathogens that are new or have evolved rapidly to change their external molecular shapes
1) Will organisms with only innate immune systems live long?
2) Why are the external molecular shapes (aka epitopes) of parasites important to understanding immunity?
3) Will a strong adaptive immune system react to all shapes?

7. 3 2
Answer: 3 is probably the best 1 4

8. 1) What kind of biomolecule is this?
Peer Instruction
1) What kind of biomolecule is this?
Light-chain Gene in a Single Immune Cell:
Adaptive immune cell
2) What part of this is molecule is likely to have a uniform structure/function between different versions?
3) What part of this molecule does the unique binding with a specific epitope?

9. 2) Is this gene processing a permanent change in the cell?
1) How is an individual antibody protein created?
Peer Instruction
Start with DNA containing full
set of V, J, and C segments.
Light-chain Gene in a Single Immune Cell:
Recombined DNA that has
been cut and rejoined.
mRNA:
One V segment joins with one J
segment and the C segment by
recombination.
Processed mRNA:
Translation results in a protein with a
unique amino acid sequence.
2) Is this gene processing a permanent change in the cell?
Light-chain protein:

10. Each antibody has a light chain and a heavy chain.
Peer Instruction
Light-chain
DNA:
Heavy-chain
DNA:
Each antibody has a light chain and a heavy chain.
Light chain: 40 ‘V’ regions, 5 ‘J’ regions, and 1 ‘C’ region
Heavy chain: 51 ‘V’, 27 ‘D’, 6 ‘J’, and a C
1) How many possible antibody shapes are there?
2) The machinery that cuts the V, D and J regions is sloppy and inconsistent in making exact cuts.
Is this good or bad for antibody diversity?
Is this good or bad for your health?

11. Concept Questions
A physician’s assistant notes that “the most important cell in the entire immune system isn’t an immune cell; it’s a common skin cell”. Do you agree or disagree? Why?
What are the health consequences for an individual born with:
A mutation that inactivates all platelets
A mutation that stops cell crawling in all immune cells
A mutation that allows bacteria or viruses to move through skin cells
A mutation that prevents innate immune cells from sending signals
In three sentences (max), give a guide for deciding whether something is an epitope or not.
Eventually, immune B cells compose a group of many thousands of cells. Each cell is 99.9% or more similar in terms of DNA to each other. However, there is a single gene that when compared to other B cells is less than 10% similar.
How can this be?
How did it happen?

12. After this class, you should be able to:
Wednesday, February 22nd, 2017
Class 29 Learning Goals
Adaptive Immunity
After this class, you should be able to:
Explain how the human adaptive immune system can prevent infections in the first patient infected (in other words: without evolving to stop that particular parasite).
Compare and contrast the roles of B cells, T cells and dendritic cells in the adaptive immune system.
Compare and contrast the humoral and cell-mediated responses.
Examine the role of MHC proteins across different cell types.

13. Peer Instruction
Binding prevented
Uninfected
host cell
Antibody
Virus
Antigen epitope
Explain two ways that antibodies fight pathogens in the ‘humoral response’
Neutrophil
Neutrophils naturally recognize and ingest
anything bound by many antibodies

14. B-cell activation
Peer Instruction
Foreign peptide
B-cell receptors
B-cell binds and presents antigen.
B-cell
MHC protein
2. The MHC-peptide complex interacts with
complementary receptors on a helper T-cell,
activating it.
Why is B-cell activation good for fighting against a particular parasite?
Activation
B-cell
Cytokines
3. Cytokines from the activated
helper T-cell activate the B-cell.
Helper T-cell
B-cell clonal expansion
Plasma
cells
Antibodies

15. Explain the cellular system of B-cell activation.
Peer Instruction
Foreign peptide
B-cell receptors
B-cell binds and presents antigen.
B-cell
MHC protein
B-cell
Cytokines
B-cell activation
Activation
Helper T-cell
B-cell clonal expansion
Plasma
cells
Antibodies

16. How do killer T-cells fight pathogens in the ‘cell mediated’ response?
Peer Instruction
Killer c T-cell
Virus-infected
host cell
Granules
How do killer T-cells fight pathogens in the ‘cell mediated’ response?
Virus particle

17. 2) How does a dendritic cell help against viruses?
Peer Instruction
1) Why is a dendritic cell like a ‘street sweeper’?
Dendritic cells in the lymph nodes absorb a
sampling of all protein available in the body
MHC
MHC proteins on dendritic cell present proteins
Antigen
Antibody-derived receptors on T-cells may
bind to dendritically-presented proteins
2) How does a dendritic cell help against viruses?
Cytotoxic ‘killer’ T-cells
Clonal expansion
Killer T cells leave lymph node -> into blood stream

18. Concept Questions
NASA is worried about Martian parasites. Before a Mars landing, patients were exposed to preserved Martian air.
Why would this help?
What cells would be activated?
If NASA could predict the proteins on the outer surface of a Martian virus, what would be the best way to help astronauts protect themselves through adaptive immunity? Explain your answer.
Grow thicker skin
Create B cells with the DNA for all possible antibodies
Create and many more B cells each with a different VDJ region
Use gene therapy to give the same VDJ region to all B cells
What cell would be most important in the response to the Ebola virus?
What cell would be most important in the response to a poison molecule in the bloodstream?
What cell would be most important in the response to a rapidly changing parasite?
Diagram the input information and final products of the:
Humoral response
Cell-mediated response
Predict three consequences of a failure to transport MHC proteins to the plasma membrane.