What is T cell Polarisation?
Cytokines determine T-cell polarization. The presence of IL-12 and/or interferon γ drives previously uncommitted T cells to become polarized to produce T1 cytokines, while IL-4 drives them to become polarized to secrete T2 cytokines.
What is the function of polarizing cytokines?
In this model, surface molecules on the APC or cytokines in the surrounding tissue environment deliver polarizing signals to naive CD4 T cells upon Ag stimulation. Such polarizing signals induce up-regulation of transcription factors that drive the differentiation of Th1 and Th2 cells.
How are T cells different from in vitro?
In vitro differentiation of Th cells from naïve CD4+ T cells is achieved by stimulating their T cell receptor (TCR) in the presence of appropriate cytokines.
How do CD4 differentiate?
Upon TCR activation triggered by antigen-presenting cells, naive CD4 T cells differentiate into distinct Th lineages in the context of combinations of cytokines. The differentiation processes involve upregulation of master transcriptional regulators and activation of STAT proteins (185).
What does Polarisation mean in immunology?
Polarization of immune cells is commonly observed in host responses associated with microbial immunity, inflammation, tumorigenesis, and tissue repair and fibrosis. In this process, immune cells adopt distinct programs and perform specialized functions in response to specific signals.
What are the roles of cytokines in the development of CD4+ T cells?
CD4+ T cells may promote the generation of effector and memory CD8+ T cell populations through many possible pathways. One such pathway involves enhancing the APC-mediated production of cytokines that augment initial CD8+ T cell responses; these cytokines include IL-1, IL-6, TNF and IL-15 (Ref. 69).
How do cytokines activate T cells?
As naïve CD8 T cells become activated they require cognate antigenic signals through their T cell receptor (TCR), costimulatory signals provided by CD28-B7 interactions, and a third signal provided by inflammatory cytokines in order to fully elicit an immune response [13].
How do T cells produce cytokines?
In culture, they cause the T cells to stimulate their own proliferation and differentiation by inducing the cells to secrete a cytokine called interleukin-2 (IL-2) and simultaneously to synthesize high affinity cell-surface receptors that bind it.
What happens when CD4 T cells are activated?
The activated CD4+ T cells undergo extensive cell division and differentiation, giving rise to distinct subsets of effector T cells (Box 1). The best characterized of these are T helper 1 (TH1) and TH2 cells, which are characterized by their production of interferon-γ (IFNγ) and interleukin-4 (IL-4), respectively1.