B cells: distribution and function of antibodies

Question 1

Name all ab fucntions - Gen= 5

Answer 1

Virus and toxin neutralization = prevent pathogen binding to target
Opsonization —> phagocytosis
Complement —> Mac
Adcc
Fc receptors

Question 2

Describe abs binding fc receptors

Answer 2

Bind fc receptors on rganulocytes = mast cells, esoinphils, basophils —> ag binding to ab triggers degranualtion (like adcc)

Question 3

Describe ab transport

Answer 3

Not ab function to clear infection but are transported so can exert fucntion

Question 4

Describe fc receptors

Answer 4

Heavy chain constant region

Question 5

Fc receptors fucntion

Answer 5

Igs opsonzie, act on cells, get across cells

Question 6

Describe fc recpetor family = gen

Answer 6

Family of cell surface tm receptors that bind fc portion igs
Expressed on macrophages, granulocytes, dcs, mast cells, B cells epithelial cells etc

Question 7

Describe fc recpetor family = binds what

Answer 7

Bonds igs in a classs specific manner - not one fits all

Question 8

Name fc receptors and what they bind

Answer 8

Fcyr = binds fc region igg
Fcer = binds fc region ige
Fclaphar = bind fc region iga

Question 9

What do fc receptors mediate - cross linking

Answer 9

Many effector fucntions of abs
Cross linking fc repcetros = imrpoatn for triggering signalling
When fc repcetros bind their abs that are bound to ag (ab bound to speciifc ag!!)

Question 10

Name the 4 fucntions of fc receptors

Answer 10

Degranulation
Opsonization
Transportation and maintenance of serum levels - trasncytosus
Adcc

Question 11

Describe advtange of using fc receptors

Answer 11

= allows non specific immune cells to take advantage of ag specific abs

Question 12

What is opsonizaiton

Answer 12

Promotes/enhances engulfment of ags by phagocytes

Question 13

Does free igg cross link fc receptors

Answer 13

Nooo
Free igg does not cross link fc repcetros = igg bound to macrophage does tho

Question 14

What allows cross linking of fc receptors

Answer 14

Aggregation of binding can allow cross linking of fc repcetros = multiple abs bind ag
= trigger intracellualr signalling= phagocytosis

Question 15

Describe igg effector fucntion

Answer 15

Several subclasses = each with distinct effector fucntions
Some igg = effective at complement fixation, some good at mediated adcc by nk cells

Question 16

wHat do all igg variants do

Answer 16

Bind to fc repcetros, enhAncing phagocytosis by macrophages (or phagocytes) —> oponization

Question 17

Define adcc

Answer 17

Antibody dependent cell mediated cytotoxicity
Activates killing activity of several types of cytotoxic cells - like nk cells

Question 18

Compare adcc and innate fucntions

Answer 18

Nk cells have fcyrs
Can recognize fc region of igg
If fc repcetros bind to abs on a cell —> cross linking triggers signalling —> nk cell releases toxic granules —> target cells die by apoptosis
Same toxic granules released in adcc and innate but activating signal sent to nk cells not the same

Question 19

Describe fc receptors and grnaulaocytes

Answer 19

Antibody dependent degranulation from granulocytes
Mechanism similar to adcc, but not same type granule release

Question 20

What is ige effector fucntion

Answer 20

Best known for allergy adn asthma
Also play role in protecting against parasitic helminths and protozoa

Question 21

Name ige potent effects

Answer 21

Made in small quantities but potent effects = degranualtion of eosinophils/basophils
Release of molecules like histamine to damage large pathogens

Question 22

Describe neutralization

Answer 22

Protects against viral or bacteria infection
Or against damaging effects of toxins

Question 23

What can be neutrazlied

Answer 23

Diff targets = toxins, viruses, bacteria (usually binds to repcetros on human cells- on surface)

Question 24

Describe purpose of neutralization

Answer 24

Binding of abs to toxins or pathogen to prevent them from binding their targets and exerting effects = anti ab = binds to that thing

Question 25

Which abs neutralize

Answer 25

Iga and igg

Question 26

What major ab isotype found in secretions

Answer 26

Iga = mucus in gut, milk from mammary glands, tears, saliva

Question 27

Describe complement activation

Answer 27

Results in generation of Mac, inflammation and/or opsonization

Question 28

Describe/summarize classical pathway

Answer 28

C1q can bind pathogen directly or bind abs bound to pathogen surface Connect adaptive to innate —> cascade, c3 convertase generated

Question 29

Which abs can trigger complement cascade

Answer 29

Igg and igm

Question 30

Which ab most effective at triggering complement cascade

Answer 30

Igm

Question 31

Describe ab transport

Answer 31

Fc repcetros = allow targeting of diff ig classes to diff parts of body

Question 32

Where iga found

Answer 32

Selectively found in mucosal tissues

Question 33

Where ige found

Answer 33

Near epithelial tissues

Question 34

Where igm found

Answer 34

In blood

Question 35

Where igg found

Answer 35

Widely distributed —> including to developing fetus Also blood

Question 36

Describe igg in fetus

Answer 36

Newborns have maternal igg in circulation = passive immunity Abs remain for 4-6 months

Question 37

What transports igs across barriers

Answer 37

Fc repcetros

Question 38

Where is igd found specifically

Answer 38

Minor component of blood = 0.2% of circulating abs But is present at higher levels in secretions of upper respiratory tract

Question 39

Describe effector functions igd

Answer 39

Binds basophils and mast cells (fc repcetros) = prompting them to release anti microbial peptides (amps), cytokines and chemokines

Question 40

What do abs mediate

Answer 40

Clearance and destruction of pathogen in variety of ways

Question 41

Describe each ab isotype

Answer 41

Has distinct properties and traits that enable it to do so

Question 42

Describe igm

Answer 42

First ab produced in primary response Tends to be lower affinity Pentavalent = 10 total ag binding sites - nice landing pad for c1q

Question 43

What is igm good at

Answer 43

Activating complement Also efficient at making dense ab-pathogen complexes that are efficiently engulfed by macrophage

Question 44

Describe c1q binding igg

Answer 44

Binds 2 igg subtypes at once