Immunology 4 Flashcards
phases of T cell maturation
cognitive phase (naive T lymphocyte activated by APC). activation phase (Il-2 autocrine growth factor). differentiation and then the effector phase
as a result of the triggering process, naive T cells stimulated to secrete? to also do what?
secrete IL2. proliferation, differentiation into various effector cells
4 examples of effector T cell actions
T helper cells for antibody production. T helper cells for delayed type hypersensitivity (activate macrophages). T helper cells for anti-parasitic and allergic reactions (activate neutrophils, eosinophils). T cytotoxic cells.
in the transition from naive to activate Th, T cells secretes?
initially only secretes IL2 = autocrine, causes proliferation
calcineurin
important for IL 2 production
best cells to trigger naive T cells
dendritic cells. B cells/macrophages will only do it under certain circumstances where they’ll also express B7
for naive Th cells to be mature effectors, what 2 things must happen
activated by APCs with appropriate MHC+peptide combination. B7 molecules (costim signal through CD28)
why are dendritic cells super presenters?
they always express B7 co stimulatory molecule
B memory cell characteristics
small, non replicating circulating B cells that express surface but not secreted antibody - similar properties to naive B cells
3 ways memory B cells carry memory
clone of B cells specific for an antigen have expanded = more cells will mount a faster response when challenged. mutations were selected to encode higher affinity Abs, and that’s preserved in the memory B cell pool. isotype and effector function of switched B cells is preserved
Ig_ for primary vs. secondary response
primary: IgM, some IgG later. secondary responses produce IgG immediately
when do you have T-independent antibody responses?
protein antigens require T cell help for B activation, but carb and lipid antigens don’t
2 ways CTLs can be activated
direct interaction with a virally infected dendritic cell. indirectly by getting some Th1 type help from a CD4 cell
CTL activation in 2 ways, but what is commonly required?
both cases you need a professional APC expressing B7 to activate
after activation, CTLs can? don’t need?
can kill any other infected cells by interacting with just Class I + viral peptide. don’t need anymore co stimulatory signals
dendritic cells express high levels of?
B7 (signal 2 via CD 28)
activated CD 8 cell makes __, driving?
IL2 = drives its own proliferation and differentiation
main mechanism of CTL killing is via (names of substances)
perforin and granzymes = fragmentins
main mechanism of CTL killing: description
CTL attaches to target, secretes perforin = pore in membrane of target cell. granzymes move into target cell = induce apoptosis
