This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
A 38 year old woman presents with fever of 103degF, hypotension, confusion and a diffuse, erythematous rash. She had uncontrollable epistaxis for which a nasal pack was placed 3 days ago. What is the likely mechanism of action of the microbial toxin that has caused her current illness? 
Select and explain. 
A. Increased antigen presentation by macrophages, B. Polyclonal activation of T-cells, C. uncontolled activation of complement, D. Enhancement of phagocytosis
B: Polyclonal activation of T-cells
Answer: B: Polyclonal activation of T-cells 
Explanation: This woman presented with fever, hypotension and a diffuse rash 3 days after a nasal packing was done. This is characteristic of toxic shock syndrome - commonly caused by Staphylococcal Toxic Shock Syndrome Toxin - 1 (TSST -1), which is a superantigen. Superantigens act by causing polyclonal activation of T cells - Activate large number of T cells irrespective of their antigen specificity. In contrast to regular antigens which bind to the binding groove on T Cells, superantigens bind outside the groove directly to the lateral aspect of TCR b chain. This leads to massive release of cytokines and polyclonal activation of T cells: Clinically, this manifests as fever, hypotension, and skin exfoliation. Examples of organisms which produce superantigens: Bacterial Staphylococcus aureus Streptococcal toxin Mycoplasma ahritidis mitogen 1 Yersinia enterocolitica Yersinia pseudotuberculosis Viral Epstein-Barr virus (EBV) Cytomegalovirus (CMV) Rabies nucleocaspid HIV-encoded negative regulatory factor. Fungal Malassezia furfur Reference: Ananthanarayan and Paniker&;s Textbook of Microbiology Tenth edition