HUBS 191 Lecture 35 Flashcards
(24 cards)
how does the degradation of endogenous proteins differ from exogenous proteins
endogenous proteins are broken down by the proteasome
exogenous proteins are broken down by phagolysosomes
how does the adaptive response differ for viruses vs bacteria
for bacteria the pathway depends on the nature of the extracellular bacteria - viruses use both pathways (CD4 and CD8)
where are T cells produced and ‘educated’
T cells are produced in the bone marrow and migrate to the thymus where they are ‘educated’
how does the thymus ‘educate’ T cells
within the thymus almost all proteins are ectopically expressed (out of their normal place) and this means that we can delete those T cells that are auto reactive
T cells express T cell receptors with co-receptors…
CD4 or CD8
a fully developed T cell recognises _________
MHC peptide complexes
once in the thymus T cells are stimulate to undergo ______
genetic rearrangements in the genome/DNA in the variable genes of the T cell receptors which will alter the shape of the TCR
the thymus gets _____ as you age meaning T cell production ______
smaller - drops off/decreases
in the thymus T cells are stimulated to undergo rearrangements and then only can be expressed ____
on the cell surface
how is diversity created in the T cell repertoire
immature T cells rearrange the ‘variable’ parts of the TCR genes in the thymus. the rearrangement process is essentially random which ensure that individual T cells are unique in terms of the TCR
what are immature T cells called
thymocytes
other than the TCR what else is selectively expressed
co-receptors CD4 and CD8 - some T cells get CD4 and some get CD8 depending on how they interacted with each type of MHC as they moved through the thymus
what do CD4 and CD8 do
assist with the docking of the T cell receptors into MHC molecules - they aren’t covalently bound so they will migrate close the the T cell receptor to assist its specificity in binding MHC
what are naive T cells
T cells that have not been activated by MHC/peptide
what are effector T cells
activated T cells
what do CD4T helper cells recognise and what is their function
CD4 T helper cells recognise MHC-2/peptide and they help CD8 cells become cytotoxic as well as helping B cells make antibody
how do CD4 T helper cells act
they secrete cytokines which are able to act on other cells to encourage their differentiation and development
what do CD8 T cells recognise and what is their function
they recognise MHC-1/peptide and they develop into cytotoxic T lymphocytes (CTLs) also known as cytotoxic T cells which kill virus infected cells
in the lymph node or spleen CD4 and CD8 T cells are usually close together so even a small amount of cytokines gives _________
a large concentration of cytokines because its such a small area
what is needed for CD8 T cells to become activated
recognition of MHC-1/peptide
and help from CD4 T cells
what are CTLs
cytotoxic T lymphocytes are CD8 T cells that leave the lymph node and find areas of inflammation that a virus is targeting
true or false - CTLs can kill one virus infected cell each
false - CTLs can kill multiple virus infected cells
in addition to the formation of effector cells, T cell activation results in the formation of _______
memory T cells
what are memory T cells
memory CD4 or CD8 T cells reside in the body for long periods of time and become effector cells much quicker than naive T cells incase of a secondary infection
