Detection of IL-17 and IL-23 in Plasma Samples of Children with Autism

Abstract

Interleukin-23 (IL-23) is a survival factor for a newly described population of T lymphocytes, namely Th-17 cells, that secrete IL-17, tumor necrosis factor- alpha (TNFα) and IL-6. It has been shown that Th-17 cells are a pathogenic T cell subset involved in autoimmune and chronic inflammatory diseases. Based on the increasing evidence of immune dysfunction in autism, including possible autoimmune and inflammatory processes, we hypothesized that Th-17 cells, a T cell lineage that has not been previously examined in this disorder, may be altered in autism. To assess the potential role, if any, of Th-17 cells in autism, we analyzed plasma samples obtained from children ranging in age from 2-5 years with a diagnosis of autism and age-matched typically developing controls for the presence of IL-17 and IL-23 cytokines. Plasma samples from 40 children with autism including 20 children with a regressive form of autism, 20 with early onset and no regression and 20 typically developing age-matched control children were analyzed for IL-17 and IL-23, under the hypothesis that altered number and function of Th-17 cells would directly correlate with altered levels of IL-17 and IL-23 in the plasma. In this study, we were able to demonstrate that IL-23 cytokine levels were significantly different in children with autism compared with age-matched controls, a finding primarily driven by children with early onset autism. In contrast, there were no statistical differences in IL-17 levels autism compared with age-matched typically developing controls. This is the first study to report altered IL-23 production in autism. The decreased plasma IL-23 production observed in children with autism warrants further research as to its affect on the generation and survival of Th-17 cells, a subset important in neuroinflammatory conditions that may include autism.