Peripheral Blood Treg/Th17 Imbalance and Altered Th2 Cytokine Profiles in Children with Autism Spectrum Disorder.

BACKGROUND: Intestinal microbial imbalance may cause immune abnormalities, contributing to autism spectrum disorder (ASD). This study investigated immune-related cytokines and T cell subpopulations in children with ASD. METHODS: In this retrospective cross-sectional study, forty-five children with ASD and 45 age- and sex-matched healthy controls were enrolled. Serum cytokines [interleukin (IL)-10, IL-4, and IL-5] and peripheral blood T cell subpopulations [regulatory T cells (Treg) and T helper type 17 (Th17) cells] were analyzed and compared between groups. RESULTS: The ASD group exhibited significantly higher Th17 cell proportions (0.41 ± 0.15% vs 0.24 ± 0.13%, P < 0.001), lower Treg cell proportions (5.72 ± 1.92% vs 9.82 ± 0.95%, P < 0.001), and a lower Treg/Th17 ratio (18.33 ± 11.57 vs 50.68 ± 14.12, P < 0.001). Serum IL-10, IL-4, and IL-5 levels were also elevated (IL-10: 59.57 ± 22.41 vs 46.71 ± 15.32 ng/L, P = 0.002). IL-10 levels positively correlated with Th17 cell proportions (r = 0.42, P = 0.004), suggesting a compensatory feedback response. All measurements were performed in peripheral blood. CONCLUSIONS: Children with ASD exhibited a significant Treg/Th17 imbalance skewed toward Th17 predominance, accompanied by elevated IL-10, IL-4, and IL-5, likely reflecting compensatory anti-inflammatory and Th2 responses. These immune markers may serve as potential biomarkers for ASD, although peripheral blood may not fully reflect gut immune status.