Antigens and Antibodies

Question 1

5 features of adaptive immune response

Answer 1

Specificity
Immunologic Memory
Diversity
Self-Regulation
Discrimination of Self vs. Non-self

Question 2

Specificity

Answer 2

due to lymphocytes having cell membrane receptors
each lymphocyte has just one specificity
Immune responses are generated toward determinants/epitopes

Question 3

Immunologic Memory

Answer 3

Faster and more vigorous immune response upon re-exposure to antigen

Question 4

Memory cells

Answer 4

more sensitive to stimulation by antigen than antigen-naive lymphocytes

Question 5

Diversity

Answer 5

you can make a lot of different lymphocytes against lots of things
this is due to the expression of cell surface receptos that can react with a diverse number of antigens

Question 6

immune responses abate with time because of:

Answer 6

removal of antigen
activated lymphocytes dying within a short peroid of time by apoptosis
regulatory immune mechanisms

Question 7

Discrimination of self vs. non-self

Answer 7

immune cells specific for self are usually destroyed or regulated
adaptive immune responses are normally directed against foreign antigens
autoimmune disease occurs when discrimination is lost

Question 8

Immunogenicity

Answer 8

properties that promote an immune response

Question 9

Antigenicity

Answer 9

properties that allow a substance to react with an antibody, used loosely to describe an immunogen

Question 10

Haptens

Answer 10

small molecules that cannot induce antibody formation but can react with antibody that it is specific for.
Must be coupled to a carrier molecule to induce antibodies
Is an antigen, but not an immunogen

Question 11

5 most important features required in order to generate an immune response against an immunogen

Answer 11

Size (larger the better)
Internal complexity (more complex the better)
Degradability (immunogen processing must occur)
Foreignness (has to be foreign)
accessibility (easy to reach areas more likely to induce an immune response)

Question 12

Linear determinants

Answer 12

formed by adjacent amino acids. T lymphocytes can only recognize these.

Question 13

conformational determinants/epitopes

Answer 13

amino acid residues from different parts of the protein brought together in 3D space

Question 14

neoantigens

Answer 14

new antigens formed by proteolysis, phosphorylation

Question 15

Most common, most immunogenic type of antigen to which the human immune system is most frequently exposed

Answer 15

Protein antigen

Question 16

Characteristics of antibodies

Answer 16

glycoprotiens that mediate their biological effects by binding to antigen in a very specific manner
not present until stimulated by antigen

Question 17

Locations of antibodies

Answer 17

surface of B lymphocytes
blood plasma and tissue fluids
surface of mast cells/basophils
secretory fluids (mucus and breast milk)

Question 18

Monoclonal antiserum

Answer 18

antibodies that bind one specific antigen

Question 19

Polyclonal antiserum

Answer 19

population of antibodies that collectively can bind to more than one particular antigen

Question 20

Titer

Answer 20

reciprocal of the last dilution of antiserum that still yields a demonstrable antibody binding reaction. To get the number, take the inverse of the smallest dilution where you get a reaction

Question 21

heavy chain

Answer 21

connected together by covalent disulfide bonds

Question 22

light chain

Answer 22

connected to heavy chains by disulfide bonds, form the antigen binding site

Question 23

hypervariable regions

Answer 23

fingertips

form the binding surface

Question 24

framework regions

Answer 24

fingers

support the hypervariable regions

Question 25

hinge region

Answer 25

allows for flexibility of antibody arms

Question 26

5 antibody classes

Answer 26

IgG, IgM, IgA, IgD, IgE

Question 27

IgG

Answer 27

most abundant immunogloblin in normal serum
secretory form = monomer
activates complement by the classical pathway
crosses placenta to convey protective immunity to fetus, in mother’s milk
main antibody produced in secondary immune response

Question 28

IgA

Answer 28

mediator of mucosal immunity
present in tears, saliva, colostrum, and milk
monomeric in serum, dimer in secretions
dimer held together by J-chain
eosinophil-mediated ADCC of parasitic infections such a helmiths

Question 29

IgM

Answer 29

secretory form = pentamer
excellent activator of complement (even better than IgG)
predominant antibody produced in primary immune response

Question 30

IgE

Answer 30

secreted as monomer
eosinophil-mediated ADCC of certain parasites
binds to cell surface receptors for IgE on basophils and mast cells to mediate allergies and anaphylaxis
Receptor is high affinity

Question 31

IgD

Answer 31

very low concentrations in serum
primarily on the surface of antigen-naive B lymphocytes
important in the transduction of signals across the plasma membrane to result in antigen-driven B cell activation

Question 32

Affinity

Answer 32

strength of binding for antigen of one antigen combining site. IgG has greater affinity than IgM

Question 33

Affinity maturation

Answer 33

average affinity for a population of antibodies will increase with repeated immunization with an antigen

Question 34

Avidity

Answer 34

overall strength of attachment which takes into account how many antigen combing sites the antibody has bound. IgM has greater avidity than IgG

Question 35

Allotype

Answer 35

differences in the constant regions of antibodies (of the same isotype) between individuals due to the presence of multiple alleles of the constant region genes in the human population

Question 36

Idiotype

Answer 36

collection of hypervariable regions contributed by heavy and light chains that form the antigen binding site