A growing field in the world of immunology is the study of T regulatory cells (Tregs), a specialized subset of T cells that has the ability to “”turn off”” the immune system after an infection has been cleared. While research has been focused on how Tregs suppress one class of lymphocytes (Th1 and Th2 cells) from proliferating and making molecules that are involved in activating the immune system, the effect of Tregs on the other major class of lymphocytes – the B cells – has received far less attention. Previous experimentation in the laboratory of Grace Lam’s supervisor, Dr. Anthony Chow, has revealed that one injection of Toxic Shock Syndrome Toxin (TSST-1) to cell cultures induces a massive systemic inflammatory response. However, repeated injections of this toxin leads to the activation of Tregs that “”calm down”” the immune response. Grace’s own research has shown that TSST-1 induced Tregs may be able to prevent activation of B cells by suppressing B cell proliferation and/or inducing B cell death. Now, she is studying the mechanisms by which this down regulation occurs. This work holds important promise for understanding and developing more effective treatment for chronic health problems caused by an overactive immune response. Diseases such as systemic sclerosis, systemic lupus erythematosus, or rheumatoid arthritis, all result from overactive B cells producing excessive amounts of antibodies that damage normal tissue. Grace hopes her research might open the possibility of employing TSST-1 induced Tregs to shut down this abnormal immune response.