Introduction to Immunology

Question 1

Why is it important to wash our hands (in regular soap, i.e. non-antimicrobial)?

Answer 1

1. Washing hands reduces risk of transmitting pathogens by person to person spread.
2. Antimicrobials destroy our commensal organisms (that do not harm us and can help keep out pathogens as they compete for resources).

Question 2

What are commensal microorganisms?

Answer 2

Those microorganisms that inhabit specific areas of the human body that do NOT cause disease or infection. They help prevent infections by competing with pathogens for space and food.

Question 3

What are opportunistic pathogens?

Answer 3

Pathogens that normally do not cause disease in a healthy individual but if the immune system is compromised then the pathogen is able to cause disease.

Question 4

What two things can help ensure a healthy immune system?

Answer 4

Diet and exercise greatly reduces the risk of any type for disease state that can inflict the human body.

Question 5

What are the four classes of pathogens? Is there another potential class?

Answer 5

Viruses
Bacteria
Fungus
Parasite
Other (potential): Prions

Question 6

What is the smallest known pathogen? How small can it be?

Answer 6

Viruses

Can be ~20nm in diameter.

Question 7

Describe the basic structure of a virus (as per notes).

Answer 7

Simple structure.
Contain a nucleic acid genome (DNA or RNA) that is enclosed by a protein coat (capsid) and sometimes a membranous envelope.

Question 8

What is a bacteriophage?

Could they be on our body/

Answer 8

1. A virus that infects bacterium.
2. Some research that suggests bacteriophage is within our mucus in mucosal linings that provide non-specific immunity. Infect and destroy bacterium that comes in contact with mucus.

Question 9

How do viruses replicate?

Answer 9

1. Viruses can only replicate within other cells and need a host (bacteria, plants, animals, humans, etc.).
2. Recognizes a host by molecules on its surface, invades past the membrane and inserts its genome into the host cells nucleic acid genome, and the host cell will produce more viruses.
3. They will continue until the host cell undergoes lysis.

Question 10

What is the most commonly encountered pathogen?

Answer 10

Bacteria

Question 11

Describe bacteria.

Answer 11

1. Unicellular microorganism.
2. Avg. size of 2 um length.
3. Lacks organized nucleus
4. Possess capability to grow and reproduce independently.
5. Typically surrounded by a rigid cell wall.
6. Can be found in many different shapes (which aids identification).

Question 12

What shapes can bacteria be found in?

Answer 12

Cocci (round), rods, bacilli, spirillum, and curved.

Question 13

T/F. bacteria can inhabit a wide variety of environments.

Answer 13

True

Question 14

T/F. Maintaining healthy flora is important in maintaining good health.

Answer 14

True

Question 15

What are the two categories of fungi?

Answer 15

Yeast

Molds

Question 16

Describe characteristics of yeast (fungi)?

Answer 16

1. Unicellular oval structures.
2. Reproduce by budding.
3. Non-photosynthetic plants.

Question 17

Describe characteristics of molds (fungi)?

Answer 17

1. Non-photosynthetic plants.
2. Multicellular
3. Forms clumps of blue-green or black (like on cheese/bread).

Question 18

What type of pathogen is Streptococcus pneumonia?

Answer 18

Bacteria

Question 19

What are parasites?

Answer 19

1. Large variety of unicellular protozoa and multicellular worms found in water and soil.
2. Causes disease by using all of host’s nutrients.
3. Classified based on their life cycle/relationship with host.

Question 20

What are prions?

Answer 20

1. Infectious substances, but not living.
2. “Prion Hypothesis” - misfolded proteins. (Debated theory)
3. Mechanism by which they cause disease is not well understood.

Question 21

Name an example of a disease state caused by a prion?

Answer 21

Creutzfeldt-Jakob Disease (CJD), a degenerative brain disease.

• Incurable and fatal.
• Often undetected until an autopsy is performed.
• Brain tissue in someone w/ CJD has holes, like sponge.

Question 22

What causes Typhoid fever?

Answer 22

Salmonella typhi, bacteria

Question 23

What causes Mononucleosis?

Answer 23

Epstein-Barr virus

Question 24

What causes Thrush?

Answer 24

Candida Albicans,

Bacteria

Question 25

What causes Tuberculosis?

Answer 25

Mycobacterium tuberculosis

Bacteria

Question 26

What causes Malaria?

Answer 26

Plasmodium falciparum

Parasite

Question 27

What are superantigens? Name one example.

Answer 27

Superantigens stimulate a much larger population of cells.
Example: Staphylococcal aureus - releases bacterial toxin which produces a massive immune response.
Symptoms: High fever, low blood pressure, coma, and … death.

Question 28

What can antigens be made of?

Answer 28

Any macromolecule in existence can elicit an immune response.
Proteins, carbohydrates, lipids, and/or nucleic acids.

Question 29

What is a hapten?

Answer 29

Non-immune stimulating compounds of small molecular weight that can be coupled with an antigen to create a new antigen. This changes the immune response stimulated.

Question 30

What is the part of the antigen called that is actually recognized by the immune system?

Answer 30

Epitope

Also called ‘antigenic determinant’.

Question 31

What are the characteristics of antigens?

Answer 31

1. Foreignness - More foreign (degree of difference to host) –> more response
2. Molecular Size - The larger the molecule the more antigenic (larger response)
3. Chemical Nature - Generally more complex the more antigenic;
4. Method of Introduction - varies whether injected, ingested or inhaled.
5. Genetic Susceptibility - genes affect how well an individual will respond to an antigen.

Question 32

What units are molecules measured in?

Answer 32

Da, dalton for size

Atomic mass unit for weight, ~ 1 nucleon = 1g/mol

Question 33

Compare some molecular size of antigens reviewed in notes and the immune response they cause?

Answer 33

1. Insulin <10,000 Da Poor response.
2. Antibody of 150,000 Da, Good response.
3. E.coli of 2,500,000,000 Da Great Response.
   Get the idea?

Question 34

Are there exceptions to the molecular size rule related to antigenicity? Example?

Answer 34

Yes there are some exceptions to the rule.
Penicillin has a molecular mass of 335 Da but is very immunogenic for some individuals.
Heparin (anticoagulant is 12,000-15000 Da is not immunogenic (fortunately).

Question 35

List the molecules which are antigenic from the greatest to the least.

Answer 35

From High to low immune response:
Proteins (Great),
Carbohydrates (Good),
Nucleic Acids (DNA/RNA) (Poor), Lipids (very poor)

Question 36

What gene helps people who posses it to have good immune responses?

Answer 36

IR gene - good immune responders compared to those who lack it.

Question 37

What methods of introduction gives the greatest antigenicity?

Answer 37

Injected subcutaneously - more potent immune response than with ingested or inhaled.

Question 38

What happens to our immune response if a vaccine dose is too large or too small?

Answer 38

If too large or small - immune response will be avoided.

Needs to be optimal concentration/amount!

Question 39

Is it possible to exhaust your immune system?

Answer 39

Yes, it is possible to manipulate the immune system and create a state of exhaustion in an individual. By repeated and vigorous stimulation by an antigen - will cause eventual ceasing of the immune response. E.g. treating an allergy.