Block 1 Review Flashcards
(37 cards)
IL-2
stimulates T cell development, proliferation, and survival; also maintains regulatrory T cells, thereby controlling immune response; produced by CD4+ and CD8+ cells
3 TFs that regulate IL-2 expression
- NFAT (from IP3/DAG pathway)
- NF-kB (from PKC pathway)
- AP-1 (Fos + Jun; from Ras pathway)
* all 3 accumulate in nucleus and bind to promotor on IL-2 gene
high-affinity IL-2 receptor chain
alpha, beta, and gamma
low-affinity IL-2 receptor chain
beta and gamma
1st cytokine produced by activated CD4+ T cells?
IL-2
how does IL-2 affinity change on activated T cells?
Naive T cells express only beta and gamma IL-2 receptor chains, so don’t bind IL-2 with high affinity. Within hours after activation, T cells produce alpha receptor chain, so the complete IL-2 receptor can bind IL-2 strongly
example of autocrine T cell stimulation?
IL-2 produced by activated T cells preferentially binds to and acts on the same T cells
IL-4
produced by Th2 cells; functions include:
- IgE production (mast cell/eosinophil activation)
- M2 activation
- mucus secretion
IL-5
Th2 cytokine that activates eosinophils
4 general properties of T cell cytokines
- produced transiently in response to antigen
- autocrine or paracrine functions
- pleiotropic (mutliple biologic actions)
- redundancy/overlap btwn cytokine functions
IFN-gamma
produced by NK cells and T cells (Th1);
- activates M1 macrophages
- stimulates expression of MHC II and B7 on dendritic cells and macrophages
IL-17
Th17 cytokine that stimulates acute inflammation
TGF-beta
inhibits T cell activation; stimulates differentiation of Th17 & regulatory T cells; activates M2 macrophages
T cell differentiation mediated by?
changes in gene expression
CD4+ effector function
activate phagocytes and B cells through cytokine secretion
CD8+ effector function
kill infected cells
most important cell surface protein for CD4+ effector function?
CD40L – expressed on active CD4+ cells; activates B cells, dendritic cells, and macrophages by binding to their CD40 receptor
CD40L
expressed on active CD4+ cells; activates B cells, dendritic cells, and macrophages by binding to their CD40 receptor
CD40 receptor
B cells, dendritic cells, and macrophages are activated when CD40L on CD4+ cell binds to their CD40 receptor
Th1 cell function
stimulate phagocyte-mediated ingestion and killing of microbes
Th2 cell function
- stimulate eosinophil-mediated immunity for defense against parasites
- role in allergic reactions
Th17 cell function
- induce inflammation to destroy extracellular bacteria and fungi
- recruit leukocytes (mainly neutrophils but also monocytes) to sites of antigen recognition
- may contribute to several inflammatory diseases (MS, IBS, rheumatoid arthritis)
regulatory T cells
inhibit CD4+ and CD8+ effector functions
Type I IFNs (alpha, beta)
induce resistance to viral infection and replication (antiviral state)
