positive regulation of T cell activation via T cell receptor contact with antigen bound to MHC molecule on antigen presenting cell

Definition

Target type: biologicalprocess

Any process that activates or increases the frequency, rate or extent of T cell activation via T cell receptor contact with antigen bound to MHC molecule on antigen presenting cell. [GOC:obol]

The activation of T cells is a complex process that involves a series of steps, ultimately leading to the destruction of infected or cancerous cells. This process is initiated by the interaction of the T cell receptor (TCR) on the T cell with an antigen presented by an antigen-presenting cell (APC). The antigen is bound to a major histocompatibility complex (MHC) molecule on the surface of the APC. This interaction triggers a signaling cascade that leads to the activation of the T cell.

Positive regulation of T cell activation refers to the mechanisms that enhance or promote this activation process. One key mechanism is the engagement of the TCR with antigen-MHC complexes. This interaction initiates a cascade of events, including:

1. **TCR Signaling:** The TCR, along with associated signaling molecules, such as CD3, is clustered at the site of interaction with the antigen-MHC complex. This clustering activates the TCR complex, leading to the phosphorylation of intracellular signaling proteins.
2. **Signal Transduction:** The phosphorylated signaling proteins initiate downstream signaling pathways, including the MAPK and NF-κB pathways. These pathways activate transcription factors that regulate the expression of genes involved in T cell activation and differentiation.
3. **Calcium Signaling:** The engagement of the TCR also leads to the influx of calcium ions into the T cell cytoplasm. Calcium ions act as second messengers, activating calcineurin and other downstream signaling molecules.
4. **Co-stimulatory Signals:** For full activation, T cells require additional co-stimulatory signals, such as the interaction of CD28 on the T cell with CD80 or CD86 on the APC. These co-stimulatory signals further amplify the TCR signaling pathways and promote T cell activation.
5. **Cytokine Production:** Activated T cells produce cytokines, such as IL-2, that further promote their own proliferation and differentiation into effector T cells.

The positive regulation of T cell activation via TCR-antigen-MHC interaction is crucial for the initiation and maintenance of immune responses. It ensures that T cells are only activated when they encounter their specific antigen, preventing unwanted immune responses. This process is carefully regulated to maintain immune homeostasis and protect against pathogens while minimizing the risk of autoimmunity.'
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Proteins (1)

Compounds (7)