Lecture 1: Intro to the immune system

Question 1

What do B cells (B lymphocytes (white blood cells)) produce?

Answer 1

Antibodies

Question 2

Where do B cells mature?

Answer 2

In the bone marrow

Question 3

What part of the immune response do B cells belong to?

Answer 3

The adaptive/acquired and humoral (fluids/lymph/blood) immune response

Question 4

What is a vaccination?

Answer 4

Introduction of a dead or weakened antigen (bacteria/virus/toxin) to the immune system so that the adaptive immune system can “meet” the antigen and produce antibodies against it so that if you run into that antigen/infection again your body already knows how to mount a response against it (so if you get sick you won’t get nearly as sick)

Question 5

What is the primary difference between the innate and adaptive immune responses?

Answer 5

The adaptive immune response has the ability to “remember” specific pathogens

The adaptive response is also systemic rather than restricted to a specific mucous membrane, such as the sinus cavity

Question 6

What are the three main characteristics of the adaptive immune response?

Answer 6

1. It is specific (through antibodies)
2. It is systemic (via the blood and lymph)
3. It has a memory

Question 7

What are the two components of the adaptive immune response?

Answer 7

1. Humoral immunity (blood and lymph systems)

2. Cellular defenses

Question 8

What are antigens?

Answer 8

An external “invader” or foreign object: essentially “non-self” material

Bacteria, viruses, fungus, toxins, pollen, and even cancerous cells

Question 9

What is immunocompetence?

Answer 9

The ability of a B cell to recognize “friend or foe,” this ability is developed while maturing in the bone marrow.

Also how to recognize and bind a particular antigen
While also developing “self-tolerance” so the immune system doesn’t attack the healthy cells of the body it belongs to

Question 10

Membrane bound antibodies

Answer 10

Expressed on the surface of B cells

Each B cell expresses one unique type of membrane bound antibody so that your adaptive immune system is highly diversified and prepared for attack

Question 11

What happens when a mature but inactive B cell meets its “perfect match” antigen?

Answer 11

The B cell becomes activated and goes into “berserker mode,” dividing and producing two specific B cell sub-types

Question 12

What two types of cells do B cells produce once activated by their antigen?

Answer 12

Effector cells: active fighters which can produce free floating versions of their membrane bound antibodies that can target the specific antigen

Memory cells: long lived “mages” that preserve the genetic code for the successful antibody that originally matched the invading antigen

Question 13

Memory B cells

Answer 13

Hang around and are able to mount a faster attack when the body is re-exposed to a previously experienced pathogen.

This is why vaccines against diseases like measles, mumps, rubella, and chickenpox are so effective. The memory B cells make our immune systems more effective so we don’t become reinfected even when re-exposed to these antigens.

The secondary immune response is both stronger and faster than the initial immune response when the B cell needed to “meet” its “perfect match” antigen for the first time

Question 14

Another name for effector B cells

Answer 14

Plasma cells

Question 15

What organelle do plasma cells have an abundance of?

Answer 15

Rough endoplasmic reticulum

This is to pump out tons of free floating antibodies

Question 16

What do free floating antibodies do?

Answer 16

They travel through the blood and lymph, binding to their antigen match, thus marking those antigens for death/phagocytosis

They can also block the binding sites on viral and bacterial toxins to prevent them from binding to your tissues

Question 17

What is agglutination?

Answer 17

When free floating antibodies (which have multiple binding sites) bind to multiple antigens forming clumps so they have a harder time getting around and are easier for macrophages to consume and digest

Question 18

Why aren’t babies immunized right after birth?

Answer 18

Because in the first few months their immune systems are passively acquired through the placenta and breast milk and their B cells can’t create memories from those acquired free floating antibodies

Question 19

History of cowpox and small pox

Answer 19

Sticking scabs from infected people into other people to confer some degree of immunity

Milkmaids (who were exposed to cowpox) wouldn’t develop small pox because the two diseases are similar enough to act like a rudimentary vaccination

So Jenner inoculated a boy with cowpox and then exposed him to smallpox but the boy didn’t get sick

Pasteur repeated this with more scientific rigor in chickens using old and weakened bacterial cultures as the initial inoculation

Vaccination comes from vacca for cow

Question 20

What is an antibody

Answer 20

a Y shaped host protein (immunoglobulin Ig_) produced in response to antigens

Question 21

Structure of an antibody

Answer 21

Y shaped
2 identical heavy chains(determine class G, A, E, D, M) IgG is most common
2 light chains (kappa or lambda)
The heavy and light chains are linked by disulfide bonds
Variable ends for binding and specificity
Base of the Y is the constant region

Question 22

Antigen binding sites

Answer 22

Antigens can bind antibodies using their membrane, cytoplasm, nucleus, organelles, or a combination of sites.

Proteins are ideal, but polysaccharides, nucleic acids, and other polymers can also be antigenic

Question 23

Pasteur “pasteurization”

Answer 23

Heat inactivation of bacteria
Worked on chicken cholera and anthrax
Also developed a rabies vaccine

Question 24

Hypo-immune diseases

Answer 24

Weakened immune response HIV/AIDS

Question 25

Hyper-immune response

Answer 25

Autoimmune, like leukemia where the body attacks itself “over reaction”

Question 26

Innate immunity

Answer 26

The immunity you have because you are you (genetics) Some people have better “natural” immunity against certain antigens than others

Question 27

Adaptive immunity

Answer 27

The immunity you develop through living

Question 28

What are the three types of lymphocytes (White blood cells)?

Answer 28

Natural Killer NK
T cells (mature in the thymus)
B cells (mature in the bone marrow)

Question 29

T cells (destroy)

Answer 29

Destroy infected cells (some bacteria, all viruses)

Question 30

B cells (destroy)

Answer 30

Secrete antibodies to attack extracellular pathogens (most bacteria)

Question 31

Where lymphocytes produce an immune response

Answer 31

Malt, Balt, Galt

lymph nodes
spleen
tonsils
appendix
peyers patches in the intestines
other mucosal associated lymphoid tissue (MALT)

Question 32

Other antigens

Answer 32

non-self human tissue (like transplants)
pollen
protozoa
you own tissue from a different part of your body (ex: arm skin grafted onto the leg)

Question 33

What are epitopes?

Answer 33

Antigen binding sites

This is a specific region on an antigen (the foreign object) that is recognized by T cells or B cells

The spot on an antigen that binds to the unique portion of the short Y arms of the antibody

Antibodies can attach to multiple antigens (because they have two N-terminal specific end sites) but that bond only occurs between the n-terminus and one specific/unique epitope

Question 34

Antigen binding sites (fab)

Answer 34

The N terminus that determines specificity of the antibody

The variable regions at the short end of the heavy and light chains combine to form this region

Question 35

Biological activity site (fc)

Answer 35

Constant region (long base of the Y) on the heavy chains

Determines the immunological fate of an antigenic microbe

Can activate the serum proteins in the immune response

Question 36

Specificity vs sensitivity

Answer 36

Specificity is the selectivity of binding a particular epitope

Sensitivity is the amount of antigen a technique can detect

Question 37

Cross reactivity

Answer 37

the ability of some antibodies to bind to epitopes that are similar to their perfect match (ex cow pox vs small pox)

Different clones of plasma cells will make antibodies to the same antigen, but some may be a more perfect fit than others

Question 38

Avidity

Answer 38

strength of the overall fit between n-terminal antigen binding sites and all of the epitopes on an antigen

Question 39

Affinity

Answer 39

the association constant between antibody and an antigen (how close/tight the fit is)

Question 40

Polyclonal antisera

Answer 40

IgM antibody isolated from human blood
Injected into rabbit, acts as an antigen
Rabbit makes anti human IgM antibodies
Multiple B cell lines against the antigen develop
These multiple lines of antibodies are isolated as a heterogeneous mixture known as polyclonal antiserum

Generally less specific, more variable, esp if one or several of the rabbits die

Question 41

Polyclonal characteristics

Answer 41

highly sensitive (because multiple epitopes are targeted by the mixture)

Not as selective, due to multiple epitope targeting that can result in background staining since some different molecules may have shared epitopes

Difficult to standardize since there can be batch to batch and lot to lot variation

Question 42

Monoclonal antibodies

Answer 42

Inject mouse with antigen
B lymphocyte cell selected based on desired epitope specificity
Fused with highly proliferative cancer cell line (myeloma) to form hybridomas (produces antibodies like B cells and retains immortality of cancer)
Hybridomas divide rabidly producing a single “cloned” cell line, producing identical antibodies
Allows unlimited production via cell culture or implantation in mouse peritoneal cavity

Question 43

Monoclonal advantages

Answer 43

Homogeneity
Absence of non-specific antibodies
No batch to batch or lot to lot variability

Question 44

Paratope

Answer 44

The (specific) region on an antibody arm that binds to the epitope region of an antigen

Question 45

Short arms can be?

Answer 45

kappa or lambda