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  2. T cell - Wikipedia

    en.wikipedia.org/wiki/T_cell

    Markers of T cell activation include CD69, CD71 and CD25 (also a marker for Treg cells), and HLA-DR (a marker of human T cell activation). CTLA-4 expression is also up-regulated on activated T cells, which in turn outcompetes CD28 for binding to the B7 proteins. This is a checkpoint mechanism to prevent over activation of the T cell.

  3. Priming (immunology) - Wikipedia

    en.wikipedia.org/wiki/Priming_(immunology)

    This activation of naive T cell is controlled by a variety of signals: recognition of antigen in the form of a peptide: MHC complex on the surface of a specialized antigen-presenting cell delivers signal 1; interaction of co-stimulatory molecules on antigen-presenting cells with receptors on T cells delivers signal 2 (one notable example ...

  4. Antigen processing - Wikipedia

    en.wikipedia.org/wiki/Antigen_processing

    The discussion that follows now concerns alpha/beta T cells. The TCR (of αβ T-cells) binds a bimolecular complex displayed at the surface of some other cells called an antigen-presenting cell (APC). This complex consists of: a fragment of an antigen lying within the groove of a histocompatibility molecule. The complex has been compared to a ...

  5. Cell-mediated immunity - Wikipedia

    en.wikipedia.org/wiki/Cell-mediated_immunity

    Cellular immunity protects the body through: T-cell mediated immunity or T-cell immunity: activating antigen-specific cytotoxic T cells that are able to induce apoptosis in body cells displaying epitopes of foreign antigen on their surface, such as virus-infected cells, cells with intracellular bacteria, and cancer cells displaying tumor antigens;

  6. Co-stimulation - Wikipedia

    en.wikipedia.org/wiki/Co-stimulation

    Activation of T cells without co-stimulation may lead to the unresponsiveness of the T cell (also called anergy), apoptosis or the acquisition of the immune tolerance. [ 3 ] The counterpart of the co-stimulatory signal is a (co-)inhibitory signal, where inhibitory molecules interact with different signaling pathways in order to arrest T cell ...

  7. Antigen presentation - Wikipedia

    en.wikipedia.org/wiki/Antigen_presentation

    Antigen presentation is a vital immune process that is essential for T cell immune response triggering. Because T cells recognize only fragmented antigens displayed on cell surfaces, antigen processing must occur before the antigen fragment can be recognized by a T-cell receptor.

  8. Kinetic-segregation model of T cell activation - Wikipedia

    en.wikipedia.org/wiki/Kinetic-segregation_model...

    The TCR/peptide-MHC complex, formed when a T cell recognises its ligand on an antigen presenting cell (APC) and the T-cell-APC contact occurs, spans a short length. This results in the formation of close contact zones between the membranes of the T cell and antigen presenting cell (~15 nm apart) around the TCR/peptide-MHC complex. [3]

  9. Humoral immunity - Wikipedia

    en.wikipedia.org/wiki/Humoral_immunity

    Step 3: A T helper cell binds to the macrophage and becomes an activated T helper cell. Step 4: The activated T helper cell binds to a B cell in order to activate the B cell. Step 5: When the B cells are activated, some B cells turn into plasma cells and are released in the blood, while other B cells become B memory cells that quicken response ...