Final answer:
The immunological synapse is the interaction between APCs and TH cells via MHC class II, leading to T cell activation. Superantigens can disrupt this by binding non-specifically, resulting in a dangerous cytokine storm.
Step-by-step explanation:
The immunological synapse refers to the specialized interaction between Antigen-Presenting Cells (APCs) and helper T lymphocyte (TH) cells, primarily through MHC class II molecules. This synaptic junction facilitates the crucial activation of T cells by APCs. When a T cell receptor (TCR) recognizes and binds to a specific foreign epitope presented within the MHC II antigen-binding cleft of an APC, along with the interaction of CD4 on the TH cell with the MHC II, a stimulation pathway is initiated. Following recognition, the APC and T cell secrete cytokines that further activate the helper T cell, which then proliferates and differentiates.
In the context of superantigens, they can bind non-specifically to MHC II molecules and TCRs, bypassing the need for specific antigen recognition. This can lead to an uncontrolled activation of T cells, resulting in a cytokine storm with potentially fatal consequences such as shock and multi-organ failure. The targeted interaction between APCs and TH cells, normally leading to a controlled immune response, is thus subverted by superantigens, demonstrating the delicate and crucial nature of the immunological synapse in health and disease.