B & T cell Development + Antigen Presentation Flashcards
what are the stages of development for a B cell?
pre-pro, pro-B, pre- B,
what occurs during B cell development?
spontaneous recombination with events generate IgM BCR with diverse antigen combining sites
what happens to immature B cells released from the bone marrow?
they express IgM receptors and are antigen reactive, travel to spleen to finish developing
what is BAFF?
B cell activating factor, provides a survival signal
What occurs during T2?
maturation with IgD, B cell fully mature, some stay in follicles of spleen while others migrate to the blood and peripheral lymph organs
what happens during receptor editing?
modifications to #D structure of binding site initiate a new round of VJ recombination
what occurs during T1 in the spleen?
negative selection, B cells that react with self molecules get deleted, rest go to T2
what is expressed of the surface of B cells?
IgM and IgD
what happens if a follicular B cell encounters an antigen?
recognizes it and gets help from helper T cell and divide exponentially
what happens with the C region of the B cells
gene expression changes as it matures and proliferates after stimulation with antigen under help from helper T cells
what is a plasma cell?
secrete large number of antibody but lose cell surface immunoglobulin
what is somatic hypermutation?
selection of B cells producing antibodies with increased affinity for the antigen
how do we get IgM and IgD?
RNA splicing (in spleen T2 has both, they generate two RNA transcripts which get processed differently)
how can different classes of Ig switch?
helper T cells guide the switch to CG, CE, CA to make IgG, IgE, IgA
what is the difference between the classes of AB?
all have same antigen binding specificity (V regions) but different constant regions on the heavy chain so they have different biological regions
what is a B1 cell?
primitive subclass of B cell, in peritoneal cavity, no IgD, have IgM w/o HT cell, more ike innate immunity- no specificity
what commits them to the T cell lineage?
a receptor called notch (it makes the assemble TCR)
when T cells arrive at the thymus what happens?
TCR not assembled, do not express CH4 or CD8 (so called double negitive)
What is significant about the TCRab cells?
CD4&8 positive, predominant in the lymph nodes and spleen
what are the two types of T cell receptors?
AB and GD
what do TCRab recognize?
proteins antigens and bind to antigen derived peptides and MHC,
diverse antigen characteristics
what do the TCRgd cells do?
CD4&8 negative, predominant on skin and mucosal surfaces recognize lipid antigens but do not use MHC, less diverse
what are the four mechanisms used by T cells to produce a diverse range of receptors?
- selection from many mini gene segment
- rocomb to join to randomly selected mini segments
- addition and deletion of nucleotides during joining of mini segments
- association of two different chains to form binding sites
what happens when the B chain rearrangement is productive?
the T cells rearrange the α chain, and the Cells become Tαβ cells