6.6 Flashcards
T cells are a part of the
adaptive immune system
T cells originate in
bone marrow, Lymphoid cell line (with B cells)
T cells differentiate in the thymus to
- Helper (CD4+) T cells
- Cytotoxic (CD8+) T cells
what are CD4/CD8
surgace glycoproteins
used to identify these types of cells in the lab
early precursors to T cells are
double negative (dont have CD4 nor CD8) then double positive (have both) finally single positive (have one of them, CD4 or CD8)
Helper T cell job
Helps B cells to become active
Cytotoxic T cells job
destroy virus infected cells and tumor cells
Define what positive selection is
in the cortex of thymus
when the T cell are double positive they interact with epithelial cells -> epithelial cells have MHC-I / MHC-II merkers on them -> it the T cell binds one of them they get to live
in positive selection, what happens to T cell who wont bind epithelial cell?
T cell is marked for apoptosis
what is negative selection
in the thymus medulla
in the medulla there are dendritics cell and macrophages that express antigenes.
if T cell binds tightly- apoptosis
if T cell binds moderetly- stay alive
what is the purpose of negative selection?
to determine if the T cell will bind the body antigene and destroys them - which is super bad
how many binding site does a T cell receptor have?
1
MHC
Major Histocompatibility Complex
where can we find MHC1?
every nucleated cell in the body
where can we find MHC2?
present on the surface of antigene presenting cells
what are antigene presenting cells?
dendritic cells
monocytes/macrophages
B cells
Th1 cells are for
activation of macrophages
Th2 cells are for
activate B lymphocytes
what are naturel killer cells?
they bind with cells and search for MHC1 complex -> if the cell doesnt have MHC1 -> killer cells kills it
which MHC does the natural killer cells use?
MHC1
