Background: Most children have uncomplicated streptococcal tonsillitis.  A minority develops Sydenham's chorea (SC), a post-streptococcal, neuropsychiatric disorder associated with anti-neuronal antibodies. While several autoantibodies such as antidopamine receptor antibodies were found elevated in children with SC compared to controls their existence and role in uncomplicated tonsillitis has not been studied. We hypothesized that unique autoantibodies would be detected in children with Sydenham's Chorea and not in children with tonsillitis.

Methods: We examined autoantibody profile from children with acute SC (aSC; n=35) and persistent (pSC; n=11) SC compared to age-matched controls with streptococcal tonsillitis within the past month (n=28) and healthy children (HC; n= 32). Sera was examined for anti-streptolysin-O (ASLO) anti-dopamine-1-receptor (D1R), anti-dopamine-2-receptor (D2R), anti tubulin and anti- Lysoganglioside (LG) titers in respect of time for clinical presentation.

Results: ASLO titers were high but similar in children with tonsillitis and aSC (p=0.071-0.51). Anti-D1R antibody was higher in aSC than in tonsillitis after 2 weeks (p=0.02-0.078). Anti-D2R antibody titers were similarly high in aSC and tonsillitis (p=0.59) participants compared to controls. anti- LG was higher among children with aSC compared to tonsilitis after 2 weeks (p=0.0081-0.026). Anti-tublin was lower in aSC compared to the tonsillitis group during the first 2 weeks only (p=0.01). Combined titers were higher in children with SC compared to controls from 2 weeks and beyond (p=0.005- 0.049).

Conclusion: Autoantibodies are higher in children with SC compared to children with tonsillitis beyond two weeks. a composite test may have implications on diagnosis and treatment of this autoimmune disorder.