Lymphocytic Cellular Maturation

Question 1

What are the different moleculars T-cells and B-cells can bind to and detect?

Answer 1

B-cells can bind anything in the plasma that is large enough from surface protein to chemicals in blood.
T-cells only bind to MHC molecules, Class I and II

Question 2

What kind of chains are used for B and T-cells?

Answer 2

B-cells – Heavy and Light Chains – Kappa/Lambda

T-cells – Alpha / Beta Chains

Question 3

How can B and T-cells make so many different combinations of antigenic receptors?

Answer 3

• -VDJC gene segements with multiple versions of each kind
• -Junctional Diversity, when nucleotides are added/subtracted
• -Hypermutation of gene segments (due to high use)

Question 4

What is the interluken that is key to maturation of lymphocytes?

Answer 4

IL-7

Question 5

When is the IgD lost from the surface of B-cell?

Answer 5

IgD is present until it matures after exposure to antigen in the lymph tissue.

Question 6

What are the steps of positive and negative selection of T-cells in the Thymus?

Answer 6

Positive Selection – must bind to self antigens at least partially, then Negative selection if they bind too tightly.

Question 7

Where does positive and negative selection occur in the thymus?

Answer 7

Positive = Cortex
Negative = Medulla

Question 8

What is the difference between B and T-cell maturation and clonal expansion?

Answer 8

• -B-cells leave the bone marrow and do not mature into plasma cells/clonal expansion until they encounter their corresponding antigen (Mantle–>Germinal Center)
• -T-cells mature in the thymus and go to the paracortex in lymphnodes and expanding when needed instructed to.