Lymphoid tissues Flashcards
Where do T cells undergo final development ?
Thymus
Where do B cells undergo maturation?
Bone marrow
What are the two types of immunity?
Specific and memory
What are the specialised receptors for T cells?
TCRs (T-cell receptor)
What are the specialised receptors for B cells?
BCRs (B-Cell receptors)
Where does the B-cell progenitor stage occur?
Bone marrow
How are B cell receptor variable regions form?
Multiple copies of V,D and J genes can be rearranged in different combinations, contributing to diversity
Distinct V and J genes
What genes are responsible for the heavy chains?
D genes
What happens to the BCR upon antigen recognition?
Somatic hypermutation occurs; resulting in antibody with greater affinity to the target, B cells will subsequently differentiation into plasma cells (antibody-producing).
Which enzyme is used to promote mutations in antibody variable region gene?
Activation induced cytidine deaminase (AID)
What does CD mean?
Cluster of differentiation, CD proteins specific to particular lymphocyte
What are primary lymphoid tissues?
sites where lymphocytes are produced, supporting lymphoid-progenitor cells that mature into B and T cells (helper and NK)
THYMUS, Bone marrow and foetal liver
What is the primary site of haemopoesis?
Bone marrow
Which cells do HSC differentiate into?
Lymphoid and myeloid progenitor cells
Where does further maturation proceed?
In the periphery
Where is the B cell repertoire generated?
Bone marrow
Which factor stimulates increased white cell production during infection?
Granulocute-colony stimulating factor
What is the definition of a repertoire?
Range of genetically distinct BCRs, or TCRs, present in a given host (larger the repertoire, the greater the number of recognisable threats)
Where do the lymphoid progenitors migrate to for antigen-independent maturation?
Thymus gland
Which specific T cell marks develop within the thymus?
TCR, CD3, CD4/8 and CD2
What is positive selection ?
Identifies whether T cells are capable of recognising peptide-MHC complexes with appropriate affinity. Positive T bind to cortical epithelial cells expressing Class I, or Class II MHC (+ self peptides) with high affinity to provide a survival signal.
Which complexes are recognised by TCRs during maturation the Thymus gland?
Peptide-MHC complexes (Class I and II MHC + self peptides)
Which cells do positive T cells bind to?
Cortical epithelial cells
Which signal is produced upon high affinity binding during positive selection?
Survival signal