Immunology 2

Question 1

how many classes of Abs? what are they?

Answer 1

5: IgG, E, A, M and D

Question 2

how are the different antibody classes distinguished from each other

Answer 2

IgG, D and A have 3 CH domains, E and M have 4. G and E only monomeric, while M and A make multimers

Question 3

IgM in secreted form: present as what structure

Answer 3

very large pentameric structure with 5 monomers condensed around a joining chain, linked to each other via carboxyl terminal disulfide bonds. so total 10 antigen combining sites

Question 4

IgA secreted: what structure?

Answer 4

dimer or trimer, condensed around a J chain, also with disulfide bonds

Question 5

main antibodies which function day to day?

Answer 5

IgG, IgM

Question 6

IgE purpose

Answer 6

allergy, and protection from worms

Question 7

titre: what?

Answer 7

concentration of Abs against the immunogen

Question 8

when immunized the first time: what happens? what about the second time?

Answer 8

first get a relatively low and slowly rising titre of IgM = primary response. secondary response = faster rising titre of IgG

Question 9

secondary response is an ____ response, because?

Answer 9

anamnestic response = it shows that the immune system remembers the antigen

Question 10

class switching example: primary to secondary response to immunization?

Answer 10

primary to secondary response: IgG has the same light chain and VH region as the original IgM, but the heavy mu chain is swapped for a gamma chain

Question 11

immune complex: what and when does it form?

Answer 11

when just the right ratio of antibodies and bi- or multi valent antigens are present in solution, an immune complex forms = large matrix of interlocked antigens + antibodies

Question 12

affinity vs. avidity

Answer 12

affinity = strength of interaction of a single determinant with a single antibody combining site. avidity = antibody with multiple binding sites binding a multi valent antigen = multiple interactions, refers to overall strength of attachment

Question 13

two types of specificity in the immune system

Answer 13

recognition specificity = determines which antigens are recognized. effector specificity = which defense mechanisms are invoked as a result

Question 14

what part of antibodies determines what type of specificity

Answer 14

Fab region = recognition of antigen. Fc regions = effector specificity

Question 15

antibody binding to antigen: what does that mediate? (3)

Answer 15

neutralizes toxin by masking active site. aggregates viruses/bacteria. neutralize bacterial/viral attachment sites, preventing entry into cells

Question 16

Fc receptors: do what?

Answer 16

specifically bind to the Fc region of different Ig isotypes: binding of antigen then triggers various effector functions of the cell

Question 17

IgE Fc receptors: where? does what

Answer 17

mast cells and basophils: bind IgE = release of mediators like HA

Question 18

IgG Fc receptors: where?purpose?

Answer 18

macrophages and granulocytes = bind IgG = effecter cell can ingest or kill antigen coated bacteria

Question 19

opsonization: what

Answer 19

enhancing phagocytosis by antibodies binding to microbes - you get antibody coated bacteria with Fc regions sticking out = can bind Fc receptors