Final answer:
Superantigens are bacterial or viral proteins that cause a nonspecific activation of helper T cells, leading to an excessive release of cytokines and a potentially fatal inflammatory response.
Step-by-step explanation:
Superantigens are bacterial or viral proteins that cause a nonspecific activation of helper T cells, leading to an excessive release of cytokines and a systemic, potentially fatal inflammatory response. When superantigens bind to MHC II molecules and the TCR ß chain outside the antigen-binding cleft, they bridge together and activate MHC II and TCR without specific foreign epitope recognition. This uncontrolled release of cytokines can have serious consequences such as a cytokine storm, which can result in decreased blood pressure, shock, multi-organ failure, and even death.