A recent study showed that 36% of children with an Autism diagnosis had significantly higher serum S100B protein levels than healthy controls and that those with severe autism had significantly higher serum S100B protein than children with mild to moderate autism.
The study was looking at levels to determine autoimmunity in Autism. Elevated S100B levels in biological fluids (CSF, blood, urine, saliva, amniotic fluid) are regarded as a biomarker of pathological conditions, including perinatal brain distress, acute brain injury, brain tumors, neuroinflammatory/neurodegenerative disorders, psychiatric disorders. In the majority of these conditions, high S100B levels indicate cell damage when standard diagnostic procedures do not reveal anything.
The study’s authors explain that S100B, “is a calcium-binding protein that is produced primarily by astrocytes. Increased serum S100B protein levels reflect neurological damage. Autoimmunity may have a role in the pathogenesis of autism in some patients. Autoantibodies may cross the blood–brain barrier and combine with brain tissue antigens, forming immune complexes and resulting in neurological damage… Furthermore, S100B protein may act as a cytokine and in vitro studies have shown that, at high levels, S100B protein can induce the neuronal expression and secretion of proinflammatory IL-6. Elevated levels of S100B have been detected in the CSF of MS patients during acute phases or exacerbations of the disease, and it has therefore been proposed that elevated S100B protein may be indicative of active cell injury and can reflect an axonal and glial pathology.”
The researchers concluded that S100B protein levels were elevated in children with autism and significantly correlated to autistic severity. They believe this may indicate the presence of an underlying neuropathological condition in those with autism. They did not find a correlation to the levels and autoimmunity but recommend further research is required to investigate the possible link between serum S100B protein levels and other autoantibodies, which are possible indicators of autoimmunity to central nervous system in autism.
The article A lack of association between elevated serum levels of S100B protein and autoimmunity in autistic children was published in the Journal of Neuroinflammation.