B and T Cell Development - Robison Flashcards
Describe a B1 cell
Made in the fetal liver Self renewing Short lived plasma cell IgM T cell independent
Describe a B2 cell
Made in the bone marrow
T cell dependent
More diversity with antibodies IgM and IgD
By just the antibodies, how can you tell the difference between a immature and mature B cell?
Mature B cells have IgD while immature B cells don’t
What kind of selection do B cells go through?
Negative selection only
What is negative selection?
If a cell binds tight, then get rid of cell (deletion) or
Change in BCR
Anergy
Describe the interaction with T cells and B cells
T helper cell communicates by bringing over an antigen and activates with CD28
Describe somatic hypermutation and class switching with B cells
B cell goes into the dark portion of the germinal center in the lymph node and becomes a centroblast
AID will then introduce mutations on the variable region and either becomes low or high affinity to the antigen. Only the high affinity will stay
Will then go to the light portion and become centrocyte. Will then go through class switching and differentiation (either plasma or memory cell)
Describe the general stages of B cell development from bone marrow to peripheral tissues
In the bone marrow: pluripotent cells to lymphoid stem cells to progenitor B cells to early pro B cells to pre B cells to immature B cells
In the lymph node: immature B cell and then activated by a T cell to become a mature B cell
Describe the general stages of T cell development
Hematopoietic cell to DN to DP to SP
TCR formation is during the DN stage
What kind of selection do T cells go throughout?
Both positive and negative
Positive- can bind to antigen tightly and to MHC loosely
Negative- binds self tightly
Describe the two signal hypothesis
Needs to signals to activate a naive T cell
Positive activation: cd28 and ICOS
Negative deactivation: BTLA, CTLA, PD
Describe superantigens
Superantigens weld together TCR and MHC II causing an inappropriate immune response
Also can cause immunosuppressive if T cells get destroyed
What does Th1 do?
Cell mediated response against viruses and bacteria
What does Th2 do?
Elicits an antibody response (parasites and worms)
What does Th17 do?
Secretes IL17 that attracts neutrophils to phagocitize stuff
What does Treg do?
Monitors the activity of T cells and is anti inflammatory
Secretes IL10 and TGF-beta
What does Tfh do?
Sends signals to help guide B cel,s in class switching
What is ADCC?
Antibody dependent cellular cytotoxicity
Mechanism where NK cells recognize the Fc portion on IgG and kill the cell
Explain IgM
Hexamer/ pentamer
Neutralization
Complement activation
Can be secreted
Describe IgG
Neutralization Complement activation Opsinization Can cross the placenta 4 subclasses
Describe IgA
Monomer or diner
Neutralization
Protection of mucosa
Opsinization
Describe IgE
Activates mast cells and basophils
Describe IgD
On mature B cells
How many chains are on the heavy portion?
4 domains Variable Joint Diverse Constant
How many domains are on the light chain?
Two domains
Variable and joint
What do follicular dendritic cells do?
House intact antigens for B cells
What is a CDR?
Regions on the antibody or TCR
Which CDR is the most variable?
CDR3
What are the two ways for the “kiss of death?”
ADCC with NK cells or
Cell surface interaction with FasL and Fas in cytotoxic T cells
