September 3, 2015 - Humoral Immunity

Question 1

Common Markers of B Cells

Answer 1

CD19 and CD20

Question 2

Somatic Recombination

Answer 2

Picking a V, D, and J region to combine together to make a unique variable region for the antibody.

There are 10⁹ possible combinations.

Question 3

Somatic Hypermutation

Answer 3

Restricted to B cells engaged with a matching antigen. Requires the help of a helper T cell and only occurs within the V-segment of the Ab gene.

Deliberate, random nucleotide substitutions in the Ab gene. Ones that lead to an inceased antigen affinity result in proliferation of the B cell and thus, a stronger antibody interaction.

Question 4

B Cell - T Cell Crosstalk

Answer 4

B cells bind with a matching antigen, and then the B cell MHC Class II receptor binds with the T Cell Receptor (TCR).

T cells tell the B cells to proliferate and differentiate. This causes isotype switching, somatic hypermutation, maturation into memory or plasma cells, and communication via chemical signals.

Question 5

Functions of Antibodies

Answer 5

1. Neutralization
2. Opsonization
3. Complement activation

Question 6

Opsonization

Answer 6

Marks a target for destruction. This is particularly important against encapsulated organisms such as H. influenzae, S. pneumoniae, N. meningitidis, K. pneumoniae .

Phagocytes bind the marked target through their Fc receptor.

Question 7

Complement Activation

Answer 7

Antibodies bound to a target can induce C1 to become activated and initiate the complement cascade.

Question 8

Professional Antigen Presenting Cells

Answer 8

Macrophages

Dendritic Cells

B Cells