Previous studies have suggested that an immune response to an infection by streptococcal bacteria may lead to Tourette Syndrome in some children. Because antibodies play an important role in the body’s defense against bacterial infections, such as those caused by Streptococcus pyogenes, it has been postulated that these molecules may be involved in the reaction. It is speculated that similarities between molecules on the brain surface and the bacterial surface may result in antibodies mistakenly attacking the brain cells of affected children. In this study we will examine various aspects of the immune system to determine whether an autoimmune reaction can be implicated in TS. Aspects to be studied include: • Whether people with Tourette Syndrome have immune cells localized in those areas of the brain affected by TS. The presence of immune cells in these areas would provide strong evidence to support the autoimmune hypothesis. • Whether children with Tourette Syndrome have more streptococcal infections than their peers and if so, why this should be the case. • Whether those with Tourette Syndrome have the same level of antibodies in their blood as healthy children of the same age. • Whether the number of a specialized white blood cell type—T helper cells—are elevated in people with TS. During infections, T helper cells are known to assist B cells in generating adequate amounts of antibodies to help ward off the infection. These studies should help us better understand whether the immune system plays a role in Tourette Syndrome. If it does, new possibilities for treatment of affected children, such as mucosal vaccination, could become possible. Ivana Kawikova, M.D., Ph.D., Alfred L. Bothwell, Ph.D., James F. Leckman, M.D. Yale School of Medicine New Haven, CT Award: $75,000 Tourette Association of America Inc. – Research Grant Award 2007-2008