Demonstration of inter- and intraspecies differences in serotonin binding sites by antibodies from an autistic child.

Serotonin (5-HT) binding sites from bovine and rat cerebral cortex membranes share pharmacological properties that allow both to be subclassified by the same criteria. We show here that [3H]5-HT binding sites from human cortex also possess pharmacological properties that follow the same subclassification scheme as for bovine and rat cortex. In addition, we show that solubilized 5-HT1 and 5-HT3 sites from all three species have an s20,w value of 3.4. Despite these similar pharmacological and physical characteristics, we can demonstrate antigenic differences between receptor types and species. Human 5-HT1A sites can be distinguished from human 5-HT1B, 5-HT2, and 5-HT3 sites and from equivalent sites in rat and bovine cortex. The anti-human 5-HT1A antibodies were discovered in the blood of an autistic child and may have clinical or etiologic significance for this disorder.