Immunological characteristics of children with autism spectrum disorder and comorbid atopic dermatitis.

Objective: Current studies on immune dysregulation in autism spectrum disorder (ASD) have not adequately accounted for the influence of common comorbidities like atopic dermatitis (AD). To address this gap, the objective of this study was to characterize the peripheral immune profile in children with both ASD and AD, and to assess whether AD comorbidity modulates the link between immune dysregulation and ASD symptoms. Methods: This single-center cross-sectional study recruited children with ASD who attended the outpatient clinic of Peking Union Medical Hospital (PUMCH) from April 2019 to September 2025. According to whether AD was present, children were divided into an ASD without AD group and an ASD with AD group. ASD severity was evaluated using standardized rating scales, and six clinical symptoms were assessed. Immunological markers, including T and B lymphocyte subsets, immunoglobulins (Ig), complete blood count, total Ig E, and cytokines, were measured. Spearman rank correlation analysis was performed to assess associations between immune markers and ASD severity and clinical symptom scores. Logistic regression analysis was used to explore whether AD moderates the relationships between immune markers and clinical symptoms. Results: A total of 72 children with ASD aged 1-11 years were included in the study. Among them, 42 were classified into the ASD without AD group and 30 into the ASD with AD group. Compared with the ASD without AD group, children in the ASD with AD group had significantly higher levels of IgG, IgG1, IgG2, IgE, eosinophils (EO), and memory CD4+ T cells (CD4 + CD45RA-/CD4+), while having significantly lower levels of 45RA + CD4+ T cells, the percentage of 45RA + CD4+ T cell, naive CD4+ T cells, and the percentage of CD8 + CD38+/CD8+ T cells. Children were further divided into mild-to-moderate ASD and severe ASD groups according to their CARS scores, and the prevalence of AD did not differ statistically between them. Ordered logistic regression analysis showed that AD had interaction effects on the associations between several immune indicators, including memory T4 cells (CD4 + CD45RA-/CD4+), 45RA + CD4+ T cells, naive CD4+ T cells, and the percentage of CD8 + CD38+/CD8+ T cells, and clinical symptoms such as picky eating, agitation, sleep disturbances, mood problems, and allergies. These findings suggest that AD may influence the relationships between specific T lymphocyte subsets and clinical symptoms in children with ASD. Conclusions: Children with ASD and comorbid AD present more pronounced allergic and inflammatory phenotypes. Immune homeostasis imbalance appears to be a characteristic immunological feature in children with ASD and AD. AD may influence with T lymphocyte subset phenotype, and further influence the comorbid clinical symptoms in children with ASD.