Blood and Lymph Unit 2-2019 Flashcards
(221 cards)
t cells have to be _______ at the site of interaction with antigen.
present. they do not secrete their receptors. the only see antigenic determinants shown to them by presenting molecules on other cells.
what happens if you neonatally thymectomize mice?
they grow up with wasting syndrome, cannot reject foreign skin grafts. If you give them a thyme transplant they are ok!
what are the 6 T cells?
5 helper T cells, 1 killer T cell
Th0
undecided precursor to helper T cells. found in paracortex. when DC brings them a correct antigen, they divide and become Th1, Th17, Th2, Tfh, or Treg cells.
what is the thing that helper T cells express on their surface?
surface marker CD4
what is the main determinant of Th0’s ultimate fate?
what the DC experienced: conditions in periphery when stimulated, what TLR is engaged, what cytokines/chemokines predominated.
Th1 Cells
delayed hypersensitivity T cells. after activated, daughters leave and circulate the body. when they find antigen, they secrete lymphokines.
what is the most important lymphokine secreted by Th1?
interferon gamma. IFNy. pro inflammatory. chemotactic for blood monocytes—>become tissue macrophages. move areas where Th1 recognizes antigen. activated IFNy, to become CLASSICALLY ACTIVATED M1 (angry) macrophages
what cytokines do macrophages release to intensify inflammation?
tumor necrosis factor alpha. TNFa. and IL-1
what is the main cause of fever and inflammation?
IL1. stimulates PGE2 which slows firing rate of temp. control neurons. activates heat generation and fever
Besides INFy, what else does a Th1 secrete?
IL-2. helps CTL (killer T cells) get activated post antigen recognition
Th17 cells
makes inflammatory lymphokine Il-17. resembles Th1, causes inflammation but it is also implicated in immune diseases.
cytokines
short range mediators made by any cell that affect behavior of the same or another cell
lymphokines
short range mediators made by lymphocytes, affect behavior of same or another cell. subset of cytokines
chemokines
small short range mediators made by any cell-primarily cause inflammation
list some cytokines
IL-1, TNFa, IL-12
list some lymphokines
IL-2, INFy, IL-4, IL-5, IL-10
list some chemokines
MIP-1 to 4, RANTES, CCL 28, CXCL16, Eotaxin, IL-8
Th2 cells
when activated leave the node, circulate until they encounter antigen. then they make IL4, IL5, and IL13 to attract ALTERNATIVELY ACTIVATED M2. these are more involved in healing (debris removal, scar, pathogen wall off).
IL-4 is chemotactic for what?
eosinophils (cells specialized for killing parasites)
Tfh (follicular helper T cells)
after DC presenting cell arrives in node, some activated Th migrate to follicles of cortex to find the B cells! These Th cells role is to help B cells that have recognized antigen, in order active and differentiate into plasma cells. Tfh secrete variety of cytokines, and stimulate B cells with direct contact to switch from secretion of IgM to IgG, A, or E.
Tfh cells tend to be________, the Tfh in the gut for example switch B cells to IgA, those in the spleen switch B cells to IgG.
heterogeneous!!!!
are Tfh of a separate lineage from Th1 and 2?
nah. its more likely that one of those buggers picked up a chemokine receptor like CXCR5 that lets them boogey over to the follicle.
Treg (regulatory cells)
a small number of Th cells suppress activation of all the other T cells. See, most regulatory T cells have CD4+/CD25+ and make TRANSCRIPTION FACTOR Foxp3. CD4=helper family. they also produce TGFbeta and IL10. they are super duper potent and one can suppress 1000 Th cells.