Elevated IL-16 expression is associated with development of immune dysfunction in children with autism.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impairments in communication skills and social behaviors. Several studies have suggested that neuroimmune dysfunction plays a significant role in the pathogenesis of ASD; however, its exact etiology is unknown. Interleukin-16 (IL-16), a chemoattractant, is associated with various inflammatory processes. However, its role in children with ASD is unclear. This study aimed to investigate whether IL-16 expression is associated with immune dysfunction in children with ASD. We examined IL-16 expression in CD4+, CD8+, CD14+, CCR3+, and CXCR7+ cells in typically developing (TD) controls and children with ASD using flow cytometry in peripheral blood mononuclear cells (PBMCs). We also investigated the expression of IL-1β+IL-16+, IL-6+IL-16+, and TNF-α+IL-16+ in TD controls and children with ASD. We further explored IL-16 mRNA and protein expression using RT-PCR and western blotting. CD4+IL-16+, CD8+IL-16+, CD14+IL-16+, CCR3+IL-16+, and CXCR7+IL-16+ cells increased significantly in children with ASD compared with TD controls. We also showed that expression of IL-1β+IL-16+, IL-6+IL-16+, and TNF-α+IL-16+ was elevated in children with ASD compared with TD controls. Moreover, IL-16 mRNA and protein expression was significantly induced in children with ASD compared with TD controls. These results suggest that IL-16 expression could play an essential role in immune alteration in children with ASD.