1 - Infectious Agents and Host Immunity

Question 1

What is a normal range for White Blood Cell count?

Answer 1

4.0 - 10 x 10^3 microliters

Question 2

What is the most numerous type of white blood cell? What does it mean if there’s an increase in this cell type?

Answer 2

Neutrophils are the most abundant WBC type.

An increase in neutrophils is diagnostic for a bacterial infection.

Question 3

What are the only WBC types that are adaptive immune cells? What are the rest?

Answer 3

Lymphocytes are adaptive immune cells.

Everything else is innate immune cells.

Question 4

What are the basic three components of immunology when considering any interaction?

Answer 4

Cells and tissues

Soluble mediators

Receptors

Question 5

What is the physiological function of the immune system?

Answer 5

Prevent infections and eradicate established infections.

Question 6

What is immunity?

Answer 6

The state of being immune to, or protected from an organism of foreign agent.

Question 7

What is innate immunity?

Answer 7

Inherent protection against organisms that are permanent from birth and DO NOT CHANGE or adapt to pathogens or foreign agents.

Question 8

What is adaptive immunity?

Answer 8

DYNAMIC protection that results from specific immune components changing or adapting to unique features of the pathogen of foreign agent.

Question 9

What decision is made when the immune system decides whether an antigen is self or non-self?

Answer 9

Self: tolerogenic immune response against self - tolerates it

Foreign/non-self: mount an innate or adaptive response

Question 10

How does the immune system decide to react to self or non-self molecules (ie what types of molecules can be present)?

Answer 10

Antigen (Ag): molecule recognized by antigen receptors

Immunogen: antigen that induces immune response

Tolerogen: antigen that induce immune unresponsiveness to subsequent doses of molecule

Question 11

What characteristics make something more likely to be an immunogen?

Answer 11

Large
Intermediate dosage
complex composition 
bacteria 
effective interaction with MHC complex.

Question 12

Rate these locations from most to least immunogenic?

Intravenous
Intragastric
Intraperitoneal
SubQ

Answer 12

SubQ > Intraperitoneal > IV >intragastric

This makes sense because the places that are more immunogenic are where things should NOT be chillin.

Question 13

How does the innate immune system recognize something as non-self? What is the speed of this?

Answer 13

Via pattern recognition receptors (PRR) with limited diversity.

This is very fast.

Question 14

How does the adaptive immune system recognize something as non-self? What is the speed of this?

Answer 14

Via antigen receptors expressed on either T or B lymphocytes with nearly unlimited diversity.

Slower than innate immune system.

Question 15

How does the body respond to an intracellular antigen vs. an extracellular antigen?

Answer 15

Intracellular: cell-mediated immunity - think T cells

Extracellular: humoral immunity - think B cells

Question 16

What is a primary immune response? What is a secondary immune response? Compare the speeds.

Answer 16

Primary: response to initial exposure to substance - usually slow.

Secondary: more rapid and stronger response to subsequent exposure to substance.

Question 17

Why do the antibody and effector T cell levels not return to their baseline levels after a primary immune response?

Answer 17

Because the memory lymphocytes are still present.

Question 18

Within adaptive NATURAL immunity, what are the two types?

Answer 18

Passive: from mom

Active: from infection

Question 19

Within adaptive ACQUIRED immunity, what are the two types?

Answer 19

Passive: Serotherapy

Active: Vaccination

Question 20

In terms of adaptive natural immunity, describe passive and active immunity. What are the benefits of each?

Answer 20

Passive: receiving preformed from mom; rapid protection for a short duration.

Active: exposure to foreign antigen during infection; slower protection and longer duration from memory lymphocytes.

Question 21

In terms of acquired natural immunity, describe passive and active immunity. What are the benefits of each?

Answer 21

Passive: receiving antibodies as therapy for rapid protection. Short duration.

Active: receiving altered foreign antigen during immunization. Slow protection and longer duration from memory lymphocytes.

Question 22

What is a live attenuated vaccine? What does it induce? What are the pros and cons?

Answer 22

Modified to decrease pathogenicity or limited growth after injection.

Induces CELLULAR response from T cells.

Pro: strong, long-long immunity
Con: may revert to virulent

Question 23

What is an inactivated vaccine? What does it induce? What are the pros and cons?

Answer 23

Pathogen inactivated by retains an immunologic epitope on surface.

Induces HUMORAL response from B cells.

Pro: stable and safer than live
Can: weaker immunity-requires booster

Question 24

How is the innate immune system activated?

Answer 24

Pattern recognition receptors recognize molecular patterns (PAMP) on bacteria, virus, fungus, or parasite.

These activate a series of proinflammatory or anti-viral signaling pathways.

NO MEMORY. Response to pathogen will be immediate and same to subsequent infection.

Question 25

What is the function of the innate immune system?

Answer 25

Provide primary defense against invading pathogens.

Always ON and does NOT require previous exposure for activation.

Question 26

What are the mechanisms that the innate immune system uses?

Answer 26

Natural barriers - epithelium (skin/mucous membranes)

Phagocytic cells such as macrophages and neutrophils

Dendritic cells

NK cells

Complement pathways

Question 27

The binding of what activates the adaptive immune system?

Answer 27

Antigen: A molecule that binds to an antibody or T cell receptor.

Epitopes: The specific part of a macromolecular antigen recognized by receptors expressed on lymphocytes

Question 28

In the adaptive immune system:
What does an antibody (B cell receptor) recognize?
What does a T cell receptor recognize?

Answer 28

Proteins and lipid antigens expressed on naive B cells.

Question 29

What is the function of adaptive immunity? What are it’s characteristics?

Answer 29

To provide an antigen-specific defense via T and B lymphocytes.

Must be activated by invading antigen to cause a cascade of events.

Allows body to prepare for future via immune memory.

Question 30

Where in the body are immune decisions made? Give examples.

Answer 30

1. Generative immune organs such as bone marrow and thymus
2. Peripheral immune organs such as the spleen, lymph nodes, and tonsils
3. Peripheral tissues: the site of infection or antigen entry