Altered immunoglobulin profiles in children with Tourette syndrome

Background: Post-infectious autoimmunity and immune deficiency have been implicated in the pathogenesis of Tourette syndrome (TS). We asked here whether B cell immunity of patients with TS differs from healthy subjects.

Methods: In two independent cross-sectional samples, we compared serum levels of IgG1, IgG2, IgG3, IgG4, IgM, IgA, and IgE in 21 patients with TS from Yale University (17 males, 4 females, 8-16 years) versus 21 healthy controls (13 males, 8 females, 7-17 years); and in 53 patients with TS from Groningen University (45 males, 8 females, 6-18 years) versus 53 healthy controls (22 males, 31 females, 6-18 years), respectively. We also investigated correlations between Ig concentrations and symptom severity. In 13 additional patients (9 males, 4 females, age range 9-14), we established Ig profiles at time points before, during, and after symptom exacerbations.

Results: IgG3 levels were significantly lower in Yale patients compared to healthy children (medians 0.28 versus 0.49 mg/ml, p=.04), while levels of IgG2, IgG4, and IgM in patients were lower at trend-level significance (p≤.10). Decreased IgG3 (medians 0.45 versus 0.52 mg/ml; p=.05) and IgM (medians 0.30 versus 0.38 mg/ml; p=.04) levels were replicated in the Groningen patients. Ig levels did not correlate with symptom severity. There was a trend-level elevation of IgG1 during symptom exacerbations (p=.09).

Conclusion: These pilot data indicate that at least some patients with TS have decreased serum IgG3, and possibly also IgM levels, though only few subjects had fully expressed Ig immunodeficiency. Whether these changes are related to TS pathogenesis needs to be investigated.