lymphocyte maturation

Question 1

Function of thymus in development of immune response

Answer 1

Thymic education of T cells

Question 2

Function of spleen in development of immune response

Answer 2

Red pulp: filters blood for foreign pathogens, removes defective erythrocytes & platelets, stores erythrocytes & platelets

White pulp: has many cell types including T & B lymphocytes

Question 3

Function of lymph nodes in development of immune response

Answer 3

Presentation of antigen to lymphocytes & mount immune response if necessary

Question 4

Where does lymphocyte development occur in mammals

Answer 4

Yolk sac of embryo –> fetal liver –> bone marrow
T cells then go to thymus
B cells mature in bone marrow, Bursa of Fabricius, Peyer’s patch or appendix

Question 5

Outcome of thymic education

Answer 5

Central tolerance (T cells don’t react to bodys own peptide antigens - negative selection)
T cell diversity in peptide recognition
Maturation of T cells

Question 6

Bone marrow education of B cells

Answer 6

Self antigen presented on stromal cells, if B cell responds:
Death by apoptosis or receptor editing (re-arranging genes to avoid recognition of self antigens - unique to B cells)

Question 7

B & T cell diversity

Answer 7

Specificity of antibody/T cell receptor determined by shape of variable region

While at B-cell progenitor stage in bone marrow/ T cell progenitor stage in thymus, B/T cells randomly rearrange variable (V), diversity (D) & joining (J) genes

Diversity as there are multiple copies of V, D & J that can be joined together in different combinations

Junctional diversity = addition of random extra nucleotides between V, D & J regions to change structure of variable regions produced