L4 Flashcards
what are CD4 t cells aka
helper t cells
what are CD8 t cells aka
cytotoxic t cells
how did the thymus get discovered
thymectomised mice
became susceptible to infection
reduced no. lymphocytes
immunodeficient
a reason why thymic function declines with age
‘involutes’ ie shrinks as we age
what 2 chains does the TCR have
alpha and beta
each chain has a variable region, constant region, hinge and then TM region
joined by disulphide bonds
which signal transducing molecules is BCR associated with
Ig alpha
and
Ig beta
whcih signal transdcuing molecule is TCR associated with
CD3
APC
antigen presenting cell
must be done for T cell recognition
What complex allows antigen to be presented
MHC (1 and 2)
major histocompatibility complex
differences between MHC 1 and 2 structure
MHC-I has one long alpha chain that forms the TM domain, and is non cov bound to Beta 2 microglobulin chain
MHC-II has 2 chains (alpha and beta) and therefore 2 TM domains
where are MHC I and II expressed
I is on most nucleated cells
II has restricted expression - macrophages, B cells
which chain is encoded by the A, B and C loci on chromosome 6
alpha chain of MHC-I
what is MHC II encoded by
DP, DQ and DR regions on chrom 6
(alpha and beta chain)
which type of antigens do MHC I typically present vs MHC II
I = intracellular antigens e.g. viral
II = extracellular antigens e.g. parasites, bacteria
where is antigen degraded in cell in MHC I process
proteosome to form peptides
what chaperone protein is MHC Class I bound to in the ER
Calnexin (is removed once B2M binds)
what chaperone protein takes calnexins place once B2M binds
calreticulin
and tapasin also binds which allows the TAP transporter to bind
what does TAP tranporter do
delivers the peptide fragmets to bind to the MHC I molecule
in MHCII process, where is antigen degraded
an endolysosome
(endosome and lysosome fuse)
what is bound to MHC II to block binding of stuff that isnt the antigenic peptide
invariant chain
when the invariant chain is cleaved, what is left bound to MHC II
short peptide fragment (CLIP)
this has to be removed to allow other peptides to bind
how is CLIP removed
HLA-DM
allows other peptides to bind
the MHC II can then travel to the surface
what mhc is CD4 associated with
class II
what mhc is CD8 associated with
class I
