lesson 8 tcells Flashcards
How does the T- recognize antigens on HLA complex (main HLA complex)
With the use of TCR, variable region, antigen specificity
types of TCR’s present on T-cells
TcR2alpha beta on d4 and cd8 and TcR1gemmadelta expressed very little
Can a t cell have more than one type of TCR?
No, A specific t cell will have a specific TCR and only 1 type with alpha betta chains or gamma delta chains
What can the structure of the TCR be compared to
can be compared to a Fab fragment on antibodies, contains two chains each with a variable region and constant region
Two different types of t cell receptors and their chain nomenclature
TCR-2 with alpha and beta chains TCR1 with delta and gamma chains
Name TCR chain regions
Variable region and constant region
TCR genetics, how is variability achieved
in a similar way to antibodies, through somatic recombination during t cell differentiation, different for alpha and for beta
Sequences for alpha chain and b chain, which ones recombine ?
alpha has V , j and c sequences where v and j recombine randomly recombine while beta has VDJ and C sequences where VDJ are the ones that recombine
How many T-cells graduate from thymus university
about 2%, hard as shit
Positive t cell selection, where and how
Through recognition of antigen and self expressed HLA (variable antigens)
Negative t cell selection when and how
happens when t cells can recognize self antigen leading to the recognition of peptides that lead to cell death
Name all interactions between a t cell and an antigen presenting cell
HLA with TCR and cd4 or 8 bound to HLA, B7 with CD28, Adhesion molecules LAF-1 with ICAM,
what are the signals necessary for T cell activation through APC
Antigen recognition, cd4,cd8 recognition of HLA, B7 and cd28 , cd3 intracellular signals
What happens if no second signal occurs, what is the second signal
anergy-antigen recognition with no activation
CTLA4 receptor
Expressed on t cells AFTER activation, involved in cessation of t cell activity and a return to homeostasis
two ways antigen presentation can fail in activating a t cell
either no B7 cd28 interaction or no antigen recognition by TCR
What happens after cd4 T-cell activation
Dendritic cell activation in lymph nodes leading to activation of t cells and differentiation of memory t cells
What happens after cd8 t cell activation
chemical signaling and release of cytotoxic granules to kill infected or tumor cells
Name immunosuppressive drugs and what they suppress
Abatacept and abatacept which are ctla4 antibodies, Cyclosporine and tacrolimus inhibiting signaling from Cd3 and thus IL-2 synthesis p.w, corticoids inhibiting IL-2 synthesis. Chimeric and humanized MoAbs Basilximab and daclizumab as anti CD-25 blocking IL-2 receptor . Rapamycin on M-tor (blocks cell cycle) and finally, Azathioprine and mycophenolate (MFF) inhibiting mitosis.
