CSIM 1.15 - Humoral Immunity

Question 1

Describe humoral immunity?

Answer 1

Immunity of the extracellular space via antibodies and complement proteins

Question 2

Name the five antibody isotypes?

Answer 2

IgM
IgG (4 subclasses)
IgA (2 subclasses)
IgE
IgD - irrelevant

Question 3

Name the five heavy chain variants found on the constant region of the antibody?

Answer 3

Mu - μ chain
Delta - δ chain
Gamma - γ chain
Alpha - α chain
Exellon - ε chain

Question 4

Name the two light chain variants found on the constant region of the antibody?

Answer 4

kappa (κ) chain

lambda (λ) chain

Question 5

Which isotype class of immunoglobulin is initially expressed by all B-cells?

Answer 5

IgM (transmembrane)

Question 6

What is isotype class switching dependant upon?

Answer 6

environmental T-cell and cytokine influences

Question 7

How do antibodies accumulate changes to their variable regions (Ag capture region)?

Answer 7

Somatic hypermutation

Question 8

What specialist functions are attributed to IgG.1?

Answer 8

Placental transfer (+++)
Classical pathway complement activation (++)

Question 9

What specialist functions are attributed to IgG.3?

Answer 9

Classical pathway complement activation (+++)
Placental transfer (++)

Question 10

What specialist functions are attributed to IgM?

Answer 10

Classical pathway complement activation (++++)

Found in serum

Question 11

What specialist functions are attributed to IgE?

Answer 11

High affinity binding to mast cells and basophils (+++)

Question 12

What specialist functions are attributed to IgA?

Answer 12

Found in tears and saliva

Question 13

Which antibody isotype has the highest degree of diffusion into extracellular sites?

Answer 13

IgG

Question 14

Variable (V), Diversity (D) and Joining (J) gene segments are all found on which region of the antibody?

Answer 14

Heavy chain of the variable region

Question 15

Variable (V) and Joining (J) gene segments are all found on which region of the antibody?

Answer 15

Light chain of the variable region

Question 16

How many Variable (V) gene segments are found on the heavy chain and the light chain of the antibody variable region?

Answer 16

Heavy - 40

Light - 70

Question 17

How many Diversity (D) gene segments are found on the heavy chain and the light chain of the antibody variable region?

Answer 17

Heavy - 25

Light - 0

Question 18

How many Joining (J) gene segments are found on the heavy chain and the light chain of the antibody variable region?

Answer 18

Heavy - 6
Light kappa (κ) chain - 5
Light lambda (λ) chain - 4

Question 19

Which genes are important in binding to recognition elements surrounding gene segments?

Answer 19

Recombination activating genes (RAG) 1 + 2

Question 20

Describe the two ways of generating B-cell receptor diversity?

Answer 20

Junctional diversity - Imprecise joining at N regions and random addition of nucleotides by terminal transferase
Somatic hypermutation

Question 21

Name the two internal immunoglobulins found on the B-cell receptor that mediate intracellular signalling? Where are they located?

Answer 21

Ig-alpha and Ig-Beta

Located on heavy chain

Question 22

To activate a B-cell which two signals are required?

Answer 22

1. Membrane bound B-Cell receptor and specific Ag

2. Clustering of Ig(X) receptors enables multiple internal Ig-alpha and Ig-Beta to associate - (Activation)

Question 23

Describe isotypic antibody differences?

Answer 23

IgG vs IgA

Question 24

Describe allotypic antibody differences?

Answer 24

IgG (mine) vs IgG (yours)

Question 25

Describe idiotypic antibody differences?

Answer 25

IgG (measles) vs IgG (chicken pox)

Question 26

Define epitope?

Answer 26

Portion of Ag molecule recognised by the antibody/receptor (same Ag may be recognised by multiple antibodies due to different epitopes)