T cell aggregation

Definition

Target type: biologicalprocess

The adhesion of one T cell to one or more other T cells via adhesion molecules. [GOC:sl, PMID:12972508]

T cell aggregation is a critical process in adaptive immunity, where T cells, a type of white blood cell, cluster together in response to specific stimuli, enhancing their ability to mount an immune response. This process is orchestrated by a complex interplay of molecular interactions and signaling pathways.

1. **Antigen Recognition:** T cell aggregation begins with the recognition of specific antigens presented by antigen-presenting cells (APCs), such as dendritic cells or macrophages. T cell receptors (TCRs) on the surface of T cells bind to antigen-MHC complexes on APCs, triggering a cascade of signaling events.

2. **Signal Transduction:** Upon TCR engagement, intracellular signaling pathways are activated. This involves phosphorylation of key signaling molecules, such as ZAP-70, Lck, and LAT, leading to the formation of signaling complexes at the immunological synapse.

3. **Adhesion Molecule Up-regulation:** Activated T cells upregulate expression of adhesion molecules, including integrins (LFA-1, VLA-4) and ICAM-1 (intercellular adhesion molecule-1). These molecules facilitate strong adhesion between T cells and APCs, as well as between T cells themselves.

4. **Cytokine Release:** Activated T cells release cytokines, such as interleukin-2 (IL-2), which promote T cell proliferation and differentiation. IL-2 also enhances the expression of adhesion molecules, further contributing to T cell aggregation.

5. **Chemokine Signaling:** Chemokines, small chemoattractant proteins, play a crucial role in directing T cell movement and aggregation. T cells express chemokine receptors, which bind to chemokines secreted by APCs and other immune cells, guiding T cells towards areas of inflammation and antigen presentation.

6. **Formation of Immune Synapses:** As T cells aggregate, they form specialized structures called immune synapses. These synapses are characterized by tight junctions between T cells and APCs, facilitating efficient antigen presentation and signal transduction.

7. **T cell Polarization:** T cell aggregation leads to polarization of T cells, with the TCR and signaling molecules localized at the immunological synapse, and effector molecules (cytokines, granules) concentrated at the opposite pole of the cell.

8. **T cell Differentiation and Function:** T cell aggregation provides a microenvironment that supports T cell differentiation and function. Within the aggregate, T cells receive signals that drive their differentiation into effector T cells (e.g., cytotoxic T cells, helper T cells), which can then carry out their specific functions in eliminating pathogens or modulating immune responses.'
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Proteins (1)

Compounds (103)