T cells and cell-mediated immunity Flashcards
(39 cards)
which T helper cells enhance inflammation
TH17
which T helper cells direct toward cell-mediated immune response
TH1
which T helper cells direct toward humoral immune response
TH2
which T helper cells promote germinal center formation in lymphoid organs
TFH
which T cells downregulate immunity
regulatory T cells (Tregs)
which T cells lyse virus-infected cells
cytotoxic T cells (CTLs)
ontogeny of T lymphocytes
prothymocytes arise in bone marrow, migrate to thymus
thymocytes (in thymus) mature
mature T cells are released from thymus and travel to peripheral lymphoid organs
await activation by antigens in lymphoid organs
TCR
T cell antigen receptor
encompasses the proteins on the surface of T cells that allow them to recognize and respond to antigen
30,000 identical copies of TCR on T cell surface
not responsible for MHC restriction (function of CD4 and CD8)
equivalent to antibodies on B cells
TCR vs antibody
TCR has only one antigen-binding site while antibody has two binding sites
TCR is never secreted
CD3
cytoplasmic tails of TCR chains are not long enough to act as signal transducers
TCR is dependent on surface proteins (CD3) to transduce signals
co-stimulatory molecules
required for full activation of T cells examples: CD28 and CD40L found on T cell surface CD28 binds B7 on APC CD40L binds CD40 on APC
what cytokine is the most potent activator of macrophages
IFN gamma
when is IL-12 produced
IL-12 is produced by macrophages and dendritic cells upon exposure to antigen
toward which pathway does IL-12 direct the immune response
IL-12 directs toward TH1 pathway (cell-mediated immune response)
toward which pathway does IL-4 direct the immune response
IL-4 directs toward TH2 pathway (humoral immune response)
what produces IL-4
IL-4 is thought to be produced by mast cells or antigen-activated T cells
early activation events of T cell activation
clustering of TCRs with MHC peptide complexes on APC
phosphoinositide pathway, RAS, MAP kinase
protein kinase C and other kinases phosphorylate transcription factors
gene transcription in T cell activation
transcription factor AP-1 initiates IL-2 cytokine production
IL-2 and IL-2 receptor produced for autocrine growth
T cell activation
early signal transduction events
gene transcription
mitosis
functions of CD4 and CD8
cell adhesion molecules
signal transduction
restriction of T cell responses to MHC class II/I
TH1 cells primarily secrete
IFN gamma
TH2 cells primarily secrete
IL-4, IL-5, and IL-13
TH2 cytokines (IL-4, IL-5, and IL-13) promote production of
IgE for anti-parasite defense
TH1 cytokine (IFN gamma) promotes
microbicidal activities of macrophages
B cell production of IgG (microbe opsonization)
with IL-2, IFN gamma generates CTLs
