Humoral Effector Mechanisms (Intervention)

Question 1

Fab region

Answer 1

the region of immunoglobulins that binds antigens

Etymology: 
scientists studying immunoglobulins digested them resulting in fragments. based on these studies they named different parts of proteins
F- fragment
ab- antigen binding
c- constant

Question 2

Fc

Answer 2

the region of immunoglobulins that activates effector functions

Etymology:
scientists studying immunoglobulins digested them resulting in fragments. based on these studies they named different parts of proteins
F- fragment
c- constant
after protein digests, immunoglobulins form different fragments

Question 3

heavy-chain isotype switching

Answer 3

B-cells respond to antigen stimulation by expressing the Heavy chain (G, M, A, E) that binds antigen most effectively

Question 4

affinity maturation

Answer 4

a process called somatic hypermutation produces slight alterations in the Fab region that produces epitopes that are better at binding anitgens

prac- reason for multiple rounds of immunization

Question 5

IgM effector function

Answer 5

critical in primary immune resonse, it activates the classic pathway of the complement system

Question 6

IgA effector functions

Answer 6

mucosal immunity: secretion of IgA into lumens of gastrointestinal and respiroatyr tracts, neutralization of microbes and toxins

Question 7

IgE

Answer 7

defense against helminths and mast cell degranulation

Question 8

IgG

Answer 8

important in secondary immune response

1. activation of the classic complement pathway
2. neutralization
3. opsonization
4. cellular cytotoxicity (direction of NK cells)
5. neonatal immunity
6. feedback inhibition of B-cell activation

Question 9

FcRn

Answer 9

etymology: Fragment Constant Receptor, neonatal isoform

f(x): to spare IgG from lysosomal degradation

Question 10

Fc gamma RI

Answer 10

f(x): promotes phagocytosis of opsonized bacteria
wh cells: expressed on phagocytes and neutrophils
wh: a receptor expressed on phagocytic cells that promotes secretion of reactive oxygen species that digest polysaccharide rich capsules and phagocytosis of particles

Question 11

polysaccharide rich capsules

Answer 11

protect bacteria from direct phagocytosis unless reactive oxygen species secretion is stimulated by neutrophils or phagocytes

Question 12

Fc gamma RIIB

Answer 12

f(x): important in limiting B cell response/ inflammation
wh cells: B cells, DCs, mast cells (inflammatory cells)
wh: a receptor expressed on inflammation cells that binds the Fc region of agglutinated antibodies and triggers limitation of antibody response

Question 13

Fc gamma RIII

Answer 13

f(x): IgG directs NK cells during antibody mediated cytotoxicity
wh cells: natural killer (NK) cells
wh: antibodies coat virally infected cells and tumors. The Fc gamma receptors on NK cells directs them to kill these pathogens through degranulation

Question 14

ADCC

Answer 14

antibody dependent cellular cytotoxicity, IgG binding to

Question 15

Fc epsilon RI

Answer 15

f(x): IgE direct inflammatory cells to degranulate during helminthic infection/ inflammation
wh cells: mast cells, basophils, eosinophils,
wh: a receptor expressed on inflammatory cells that works with IL-5 from helper T cells to promote inflammation

Question 16

complement system in innate immunity (2)

Answer 16

1. lectin-mannose pathway: mannose binding lectin binds to pathogens
2. alternative pathway: C3b particles bind to polysaccharide residues on pathogens

• both these pathways skip C1, but the lectin pathway and classical pathway share many similarities

Question 17

complement system in adaptive immunity (1)

Answer 17

1. classical pathway- IgG directed binding of C1 to pathogens activates C3 formation of a C3 convertase and subsequent effector functions of C3a and b

Question 18

C3 convertase

Answer 18

an enzyme that cleaves C3 complement protein into C3a and C3b componenets

classical and lectin: C4b2a
alternative pathway: C3b and bb

Question 19

C5 convertase

Answer 19

an enzyme that cleaves complement C5 into C5a and C5b (membrane attack)

classical and lectin pathways: C4b,2a,C3b
alternative pathway: C3b,Bb,C3b,C5

Question 20

Membrane Attack Complex

Answer 20

C6, C7, C8, C9, starring C5b

formation of complements on the membrane of pathogens causes lysis

Question 21

CRI

Answer 21

f(x): complement mediate phagocytosis
wh cells: a receptor expressed on phagocytes
wh: a receptor expressed on phagocytes that functions as an opsonin

Question 22

CR2

Answer 22

f(x): complement mediated activation of the innate immune system
wh cells: expressed on B lymphocytes
wh: B cells bind to C3d, a complement protein coating microbes, and the receptor signaling promotes activation. This is especially potent in germinal centers

Question 23

C3d

Answer 23

a break down product of C3 complement that coats microbes and causes B lymphocyte activation

Question 24

systemic lupus erythematosus

Answer 24

a defciency of C2 and C4, early proteins in the classic and lectin pathways of complement activation

Question 25

DAF

Answer 25

decay accelerating factor, a protein that limits complement activation by disrupting binding of Bb and C3b

Question 26

MCP

Answer 26

Membrane Cofactor Protein, serves as a cofactor for “factor 1” in the reaction that degrades C3b formation

Question 27

Factor 1

Answer 27

a protein that degrades C3b into an inactive form

Question 28

C1 INH

Answer 28

inhibits the classical complement in its early stages

Question 29

hereditary angioneurotic edema

Answer 29

Deficiency of C1 INH causes excessive C1 activation and leakage of fluid into the laryxn and other tissues

Question 30

paroxysmal nocturnal hemoglobinuria

Answer 30

lysis of erythrocytes due to defective cell surface proteins that normally bind DAF, a factor that limits complement activation

Question 31

TGF-beta

Answer 31

a cytokine that promotes isotype switching to IgA in mucosa-associated lymphoid tissues

Question 32

poly Ig receptors

Answer 32

special receptors expressed in mucosal epithelia that allow translocation into lumenal compartments