T-helper 1 cell activation

Definition

Target type: biologicalprocess

The change in morphology and behavior of a T-helper 1 cell resulting from exposure to a mitogen, cytokine, chemokine, cellular ligand, or an antigen for which it is specific. [CL:0000545, GOC:BHF]

T-helper 1 (Th1) cell activation is a complex process initiated by the recognition of antigen presented by antigen-presenting cells (APCs), such as dendritic cells (DCs). This recognition occurs via the interaction of the T cell receptor (TCR) on the Th1 cell with the major histocompatibility complex (MHC) class II molecule on the APC, which presents the antigen peptide.

Upon TCR engagement, a series of signaling cascades are activated within the Th1 cell. This includes the phosphorylation of key signaling molecules like ZAP-70 and the activation of downstream pathways involving mitogen-activated protein kinases (MAPKs) and the nuclear factor kappa B (NF-κB).

These signaling events lead to the induction of transcription factors, including T-bet and STAT4, which promote the expression of Th1-specific genes. This includes the production of cytokines like interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), and lymphotoxin-α (LT-α).

IFN-γ plays a crucial role in Th1 cell differentiation and function. It acts as a potent activator of macrophages, enhancing their ability to kill intracellular pathogens. It also contributes to the development of cell-mediated immunity by promoting the differentiation of cytotoxic T lymphocytes (CTLs).

The activation of Th1 cells is tightly regulated by a complex interplay of cytokines and transcription factors. Interleukin-12 (IL-12) produced by APCs is a key driver of Th1 differentiation, while IL-4 produced by Th2 cells inhibits Th1 development.

Th1 cell activation and subsequent cytokine production play a critical role in host defense against intracellular pathogens, such as viruses, bacteria, and parasites. They also contribute to the development of autoimmune diseases and inflammatory responses.

Overall, Th1 cell activation is a complex process involving TCR signaling, transcription factor activation, and cytokine production, ultimately leading to the development of a robust cell-mediated immune response.'
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Proteins (1)

Compounds (4)