Antibodies against Group A Streptococcus, dopamine receptors, and ganglioside GM1 cross-react with a variety of food antigens, potentially interfering with biomarkers for PANS and PANDAS

Group A Streptococcus (GAS) is a bacteria that manifests itself in a variety of diseases, from strep throat to neuroautoimmune psychiatric disorders, such as pediatric acute-onset neuropsychiatric syndrome (PANS) or pediatric autoimmune neuropsychiatric disorder associated with streptococcal infections (PANDAS). Dopamine 1 and dopamine 2 (D₁ and D₂) receptors and asialoganglioside (GM₁) are used commercially as biomarkers in assessing neuropsychiatric diseases. However, some studies have found these antibodies in healthy subjects. Since previous research has shown cross-reactivity between foods and tissue antigens, we sought to determine whether or not cross-reactivity exists between GAS, D₁, D₂ receptors, GM₁ and commonly consumed foods, and whether the presence of food antibodies may be responsible for the false positivity. We reacted antibodies against GAS, D₁, D₂ receptors, and GM₁ with the antigens of 180 foods using the ELISA method. Anti-GAS antibodies had significant cross-reactivity with 17/180 foods, anti-D₁ antibody with 26/180 foods, anti-D₂ antibody with 20/180 foods, and anti-GM₁ antibody with 47/180 foods. Our results indicate that the presence in blood of antibodies to GAS, D₁, D₂ and GM₁ that cross-react with food antigens may not only interfere with the accurate measurement of these biomarkers of PANS and PANDAS, but show that these patients with these antibodies in their blood may not have these conditions at all, but just have innocuous antibodies against food antigens.