Serum IL-6, IL-8, and Th/Ts ratio for severity assessment and short-term clinical outcome risk stratification in pediatric Mycoplasma pneumoniae pneumonia: insights into inflammation-immune imbalance.

Mycoplasma pneumoniae pneumonia (MPP) exhibits significant clinical heterogeneity in children. This study investigated the clinical utility of serum interleukin-6 (IL-6), interleukin-8 (IL-8), and the T helper/T suppressor (Th/Ts) cell ratio for evaluating disease severity and 1-month short-term clinical outcomes in pediatric MPP. We retrospectively enrolled 194 hospitalized children with MPP without co-infection (102 mild, 92 severe; 171 favorable short-term clinical outcome, 23 poor short-term clinical outcome). Core biomarker levels were compared between groups. Diagnostic performance was evaluated using receiver operating characteristic (ROC) curves. Bootstrap mediation analysis was used to explore the statistical association pathway between systemic inflammation and cellular immune status. For short-term outcome risk stratification, LASSO logistic regression was performed as a sensitivity analysis, and candidate prognostic models were compared. Patients with severe MPP and poor short-term clinical outcomes exhibited significantly elevated IL-6 and IL-8 levels and a reduced Th/Ts ratio (all P < 0.001). A combined diagnostic model incorporating these three biomarkers achieved an AUC of 0.943 for predicting severe MPP. Mediation analysis suggested that the Th/Ts ratio partially mediated the associations of IL-6 (30.3%) and IL-8 (19.2%) with disease severity. For short-term outcome risk stratification, a parsimonious exploratory nomogram incorporating lactate dehydrogenase (LDH), IL-6, and the Th/Ts ratio showed favorable internal performance (C-index = 0.89), calibration, and clinical net benefit.Conclusions: Pediatric MPP is characterized by an inflammation-immune imbalance pattern involving elevated IL-6 and IL-8 levels and a reduced Th/Ts ratio. The LDH, IL-6, and Th/Ts ratio-based nomogram may serve as an exploratory risk-stratification tool for 1-month short-term clinical outcomes, but external validation in multicenter prospective cohorts is required before routine clinical application.