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
