B cell and T cell maturation Flashcards
Initial BCR complex present on immature B cells in BM consists of:
membrane bound IgM
CD79a CD79b
How can you differentiate three groups of pro B cells?
Early have TdT only
Intermediate have both TdT and CD45R
Late have CD45R and downregulated TdT
What is CD45R?
receptor for cell growth and differentiation
What binds stem cell factor on bone marrow stromal cells to induce pro-Bcells to proliferate and differentiate into precursor B cells?
cKit
Go look at slide 7 from the lecture…
it has a nice timeline of when what is expressed.
Which comes first pro or pre b-cells?
PRO
How can pre-Bcells be divided?
Large– mitotically active
small– non-dividing
What two different time do you see activity of RAG1/2? Why?
Early pro-B-cell, rearranging of heavy chain Ig (V-D-J)
small Pre-Bcell, rearranging of light chain Ig (V-J)
What cytokine stimulates division and differentiation of Pre-B cells into immature B-cells?
IL-7
Ig’s present on immature B-cell surface when they leave the bone marrow?
IgM
IgD
Mutation of the gene encoding Btk enzyme involved in signal transduction down stream of pre-BCR and BCR –> very few circulating B-cells and negligible serum Ig:
XLA immunodeficiency
Mutations on CD40L on T-cells, B-cell CD19, ICOS, and TACI have been identified in?
common variable immunodeficiency (CVID)
Two options for B-cells that recognize self antigen in bone marrow:
- die (apop)
2. back to the drawing board for another try at kappa/lamda chain editing of the light chain
Primary T-cell Independent (TI) antigen in TI-1 group?
LPS
Primary TI antigen in TI-2 group?
large polysaccharides
