What two signals are required for T lymphocyte activation by dendritic APCs?

What two signals are required for T lymphocyte activation by dendritic APCs?

• A. Binding of IgG with CD4 and costimulation with CD80
• B. Binding of MHC I with CD8 and IL-2
• C. Binding of MHC II with TLR and B7 with CD28
• D. Binding of CD40 with CD40L and cytokine signaling

Answer: (C)

For T lymphocyte activation by dendritic antigen-presenting cells (APCs), the process requires two essential signals. The correct answer highlights the binding of MHC II with T cell receptors (TCRs), accompanied by costimulation involving the interaction of B7 (CD80/CD86) with CD28. When a dendritic cell encounters an antigen, it processes and presents it on MHC II molecules. T helper cells (CD4+ T cells) recognize this peptide-MHC II complex through their TCR. This first signal is crucial for T cell activation, as it ensures that T cells are responding to a specific antigen presented by the APC. The second signal, which is also critical for full T cell activation, involves costimulatory molecules. Dendritic cells express B7 molecules (CD80/CD86) upon activation, which then bind to CD28 on T cells. This interaction provides a necessary additional signal that not only enhances the activation process but is also important for preventing anergy (a state of unresponsiveness) in T cells. This dual-signal requirement is fundamental in ensuring that T cells are properly activated in response to infections or other immune challenges, while also providing a safeguard against inappropriate activation that could lead to autoim

For T lymphocyte activation by dendritic antigen-presenting cells (APCs), the process requires two essential signals. The correct answer highlights the binding of MHC II with T cell receptors (TCRs), accompanied by costimulation involving the interaction of B7 (CD80/CD86) with CD28.

When a dendritic cell encounters an antigen, it processes and presents it on MHC II molecules. T helper cells (CD4+ T cells) recognize this peptide-MHC II complex through their TCR. This first signal is crucial for T cell activation, as it ensures that T cells are responding to a specific antigen presented by the APC.

The second signal, which is also critical for full T cell activation, involves costimulatory molecules. Dendritic cells express B7 molecules (CD80/CD86) upon activation, which then bind to CD28 on T cells. This interaction provides a necessary additional signal that not only enhances the activation process but is also important for preventing anergy (a state of unresponsiveness) in T cells.

This dual-signal requirement is fundamental in ensuring that T cells are properly activated in response to infections or other immune challenges, while also providing a safeguard against inappropriate activation that could lead to autoim