Toxic Shock Syndrome

A toxin is a chemical that acts as a poison within the body. TSS is caused by toxins released from certain strains of Staph. aureus and Strep. pyrogenes. Not all strains of these bacteria release these toxins. About 30% of Staph aureus strains and less than 10% of Strep pyrogenes strains are TSS-toxin-producing.

Toxins that cause TSS are called "superantigens" because of their effects on the immune system. An antigen is the protein on a bacterial cell or viral coat that certain immune cells, called helper T cells, identify as "foreign." Helper T cells recognize antigens by binding to them. When this recognition occurs, the immune system swings into action against the invader and makes specific proteins, called antibodies, which tag the invader for destruction by other immune cells. The TSS toxins are superantigens because the immune reaction they incite is nonspecific and aggressive. Helper T cells binds to the toxins, but instead of activating one small part of the immune system—the antibody production mechanism—the helper T cells-toxin binding "turns on" all of the immune system.

This nonspecific activation of the immune system has devastating effects on the body. As a result of TSS-toxins binding to helper T cells, several immune proteins are overproduced. Monokines and lymphokines, proteins that promote the further proliferation of helper T cells, are produced in large quantities. Histamine, a protein that functions in allergic reactions and the inflammatory response, is released from immune cells. These proteins, in turn, exert several physiological effects. Histamine causes blood vessels to dilate, increasing blood circulation. Monokines and lymphokines contribute to the body's fever response, in which the internal temperature of the body increases in response to an immune signal. The combination of all these effects leads to TSS.