T cell mediated immunity Flashcards
function of effector and memory CD4+ T cells
activate macrophages, B cells, other cells
function of effector and memory CD8+ T cells
kill infected target cells; macrophage activation
effector cells ____ # memory cells
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what happens when dendritic cells meet antigen? where are they?
skin: take up antigen, enter draining lymphatic vessel; settle in T cell areas
do dendritic cells have MHC I or II?
both
selectins, integrins, chemokine receptors on T cells
control migration of naive T cells in and out of lymph nodes
how do T cells enter a lymph node
through blood or through lymph
requirements for stimulating naive T cells
- antigen recognition
2. costim signal = B7/CD28
when are B7 and CD28 upregulated and why is this timing important
- during innate immune response
- want immune system to respond to microbes but not to harmless antigens
recognition of specific antigen without costim leads to
anergy
does B7-2 appear on unstimulated cells?
yes - low levels (constitutive expression)
what is the major initial ligans for CD28? what comes later?
-B7-2
B7-1 comes later, sustains T cell activation
when is CD28 not required? why?
- some CD8+ T cells (high avidity, strong signal 1)
- gamma-delta T cells
- effector and memory T cells
- use alternative costim pathways
IL-2 drives
prolif and differentiation of activated naive T cell
how do T cells migrate to site of infection
selectins, integrins, chemokine receptors
CD4+ T cells rely on ____ to activate other cells
CD40 ligand
interaction between B cell and T cell with specificity for same antigen
cognate interaction
determines whether a CD4+ T cell becomes a Th1 or Th2 type after activation
cytokine exposure
determines outcome of intracellular infections
balance of Th1 and Th2
how do Th1 and Th2 interact
Th1 leads to better outcome bu stimulating INF-gamma and TNF; Th2 can inhibit activity of macrophages
cytotoxic T lymphocytes (CTLs)
CD8+ T cells
what molecules do CD4+ Th1 cells stimulate? ( effector functions)
INF-gamma and CD40 ligand, Fas ligand, TNF-B and -a, IL-2, CXCL2
how do some virus-infected dendritic cells activate a virus-specific CD8+ T cell on their own
dendritic cell activates CD8 T cell, T cell now has effector status and makes IL-2, which drives CD8 T cell’s own prolif
how do dendritic cells activate a virus-specific CD8+ T cell using help from other cells
dendritic cel activates virus-specific CD4+ T cell, which makes IL-2, and CD8+, which expresses IL-2 receptors
