Superantigen causes-
1.Superantigensare a class of molecules that can interact with APCs and T lymphocytes in a nonspecific way(attach to TCR by the side not in tne centre) . The superantigens act differently by interacting with MHC class II molecules of the APC and the Vb domain of the T-lymphocyte receptor. This interaction results in the polyclonal activation of a larger number of T cells (10%) than conventional antigens (1%), leading to massive cytokine expression and immunomodulation. fig:-Mechanism of action of superantigen 2. Examples: Staphylococcal toxin: TSST, Exfoliative toxin, Enterotoxins, Streptococcal toxin: Streptococcal pyrogenic exotoxin (SPE)-A Viral: EBV, CMV, Rabies nucleocapsid, HIV encoded nef (negative regulatory factor) Fungal superantigen: Malassezia furfur
Polyclonal activation of T-cells
Stimulation of B cells
Enhancement of phagocytosis
Activation of complement
Immunology Pa 1 (Immune Response, Antigen-Antibody Reactions, Hypersensitivity, Structure of Immune System, Immunodeficiency Disorders)