OBJECTIVE: It has been hypothesized that Sydenham's chorea, a major manifestation of rheumatic fever, may provide a medical model for obsessive-compulsive disorder and associated conditions, such as Tourette's syndrome. Monoclonal antibody D8/17 identifies a B lymphocyte antigen with expanded expression in nearly all patients with rheumatic fever and is thought to be a trait marker for susceptibility to this complication of group A streptococcal infection. The authors investigated whether D8/17 expression is greater than normal in some forms of obsessive-compulsive disorder and Tourette's syndrome. METHOD: By immunofluorescence techniques, 31 patients with childhood-onset obsessive-compulsive disorder and/or Tourette's syndrome or chronic tic disorder and 21 healthy comparison subjects were evaluated for percentage of D8/17-positive B cells. None had rheumatic fever or Sydenham's chorea. Levels of antineuronal antibodies and streptococcal antibodies were also determined. RESULTS: The average percentage of B cells expressing the D8/17 antigen was significantly higher in the patients (mean = 22%, SD = 5%) than in the comparison subjects (mean = 9%, SD = 2%). When classified categorically, all patients but only one comparison subject were D8/17 positive. No difference between groups in the presence of antineuronal antibodies or high streptococcal titers was found. CONCLUSIONS: Patients with childhood-onset obsessive- compulsive disorder or Tourette's syndrome had significantly greater B cell D8/17 expression than comparison subjects despite the absence of documented Sydenham's chorea or rheumatic fever. These findings suggest that D8/17 may serve as a marker for susceptibility among some forms of childhood-onset obsessive-compulsive disorder and Tourette's syndrome, as well as rheumatic fever or Sydenham's chorea.Abstract Teaser