anatomy and surveillance Flashcards
(33 cards)
what T cells are removed during clonal deletion ?
the ones that bind too tightly to self MHC peptide complex
the large number of lymphocytes that are produced from a single progenitor , do they all have the same specificity?
no they all have a different specificity
how does the T cell precursor produce diversity and where does this occur ?
in the thymus it rearranges it’s T cell genes through somatic recombination.The TCR are diverse
what happens in the thymus if the immature T cell recognises self MHC and binds moderately ?
it receives a signal for survival
what happens to the T cells that interact with self antigens ?
they are removed by apoptosis
what happens to the mature T cell after selection has occured ?
move to the periphery lymphoid organs from the thymus and it is here that they encounter foreign antigens and become activated and matured fully.
what happens once the T cells become activated ?
they acquire effector functions. The activated T cells then proliferate and migrate to the site of infection to eliminate it.
name the primary lymphoid organs ?
thymus and bone marrow
what are lymph nodes ?
small glands that filter lymph that circulates the lymphatic system.
what are the lymph nodes ideal for ?
ideal environment for communication of immune cells
where do the lymphocytes encounter and respond to antigens ?
in the peripheral lymphoid organs
what is the Peyers patch ?
this is the lymphoid organ that is near the intestine
what is situated in the inner paracortical area ?
this is where the T cell are
what is situated in the outer area called primary lymphoid organ ?
this is where the B cells are
do the B and T cells have seperate areas or are they in the same section ?
separate areas
what occurs in the germinal centre ?
the B and T cells meet and they can activate each other
what does the naive T cells do ?
migrate through the secondary lymphoid tissues
what does the dendritic cells act as in the lymphoid organ ?
act as APC in the T cell area of the lymph node so that they can initially activate the naive T cell.
what happens if the naive T cell does not become activated by the dendritic APC in the lymph node ?
it exits the lymph node via the cortical sinuses
how do naive lymphocytes enter the lymph nodes ?
via the blood
how are peptides presented to the TCR in context of the MHC ?
in two forms
– MHC-I - CD8+ T cells – killer cells
– MHC-II - CD4+ T cells – helper T cell
how is the adaptive immune response initiated?
by the antigen and antigen presenting cells in the secondary lymphoid organs.
what occurs if the T cell recognises the antigen/MHC ?
T cell and APC have an interaction and the TCR transmits a signal and the T cell becomes activated
what happens once the T cell becomes active ?
proliferates it can no longer exit the lymph node and it is here that it differentiates into the effector cell of either Cd4+ or Cd8+ and then exits the lymph node.
