100384 - Altered CD4⁺ T Helper cell subsets in children with Severe Asthma: A focus on Th1, Th2, and Th17 Cells

Pediatric asthma is a heterogeneous chronic inflammatory airway disease whose immunological mechanisms remain incompletely characterized. While asthma has traditionally been described as a Th2-driven disorder, increasing evidence suggests that multiple CD4⁺ T helper (Th) cell subsets contribute to disease heterogeneity and severity, particularly in children. This study aimed to evaluate the distribution of circulating CD4⁺ T helper cell subsets (Th1, Th2, and Th17) in children with severe asthma compared with healthy controls, in order to better understand the cellular immune profile associated with pediatric asthma severity.

A prospective observational case–control study was conducted including 11 children with severe asthma and 11 age-matched healthy controls. Peripheral blood samples were analyzed by flow cytometry after in vitro stimulation. Th1, Th2, and Th17 cells were identified as CD3⁺CD8⁻ cells producing interferon-γ, interleukin-4, or interleukin-17, respectively. Frequencies were expressed as percentages of cytokine-producing CD4⁺ T cells.

No significant differences were observed in the frequencies of Th1 and Th2 cells between severe asthma patients and healthy controls. In contrast, a pronounced and statistically significant reduction in circulating Th17 cells was detected in children with severe asthma compared with controls (p < 0.0001).

Pediatric severe asthma is associated with a distinct CD4⁺ T helper cell profile characterized by decreased Th17 cells rather than altered Th1 or Th2 responses. These results highlight the complexity of immune dysregulation in childhood asthma and support further investigation into immune endotypes to inform targeted therapies.