Objective: This study aims to investigate the correlation between blood leukocyte, CRP, LDH, and cytokine levels and the severity of illness in children with adenovirus pneumonia. Methods: A total of 100 children with adenovirus pneumonia (55 mild cases and 45 severe cases) who were treated at Guangzhou Women and Children’s Medical Center from January 2022 to January 2024, and 40 healthy children as a control group, were selected. Clinical data, some laboratory test data, and serum cytokine levels detected by flow cytometry were collected, and statistical methods were used to analyze the correlation between relevant indicators and the severity of the illness. Results: The research showed that among general clinical manifestations, the proportions of children with fever, dyspnea, pleural effusion, and moist rales in the severe group were all higher than those in the mild group (p < 0.05). Among the collected laboratory test data, indicators such as WBC, neutrophils, and LDH were significantly higher than in the mild group and the control group (p < 0.05) and were positively correlated with the severity of the disease. Regarding the tested cytokines, most children with adenovirus pneumonia showed elevated levels, and cytokines such as IL-6, IL-2, and IL-8 were significantly positively correlated with the disease. In the ROC curve analysis, NEU 6.03 × 10⁹/L (sensitivity 82.2%, specificity 72.7%, AUC 0.830) and IL-6 41.823 pg/mL (sensitivity 75.6%, specificity 81.8%, AUC 0.833) demonstrated certain value in the early identification of children with severe disease. Conclusion: In this study, laboratory indicators (C-reactive protein, lactate dehydrogenase, neutrophils, etc.) and changes in the levels of specific cytokines (TNF-β, IL-2, IL-6, IL-8, etc.) in children with adenovirus pneumonia were closely related to the severity of the disease. Notably, neutrophil count and interleukin-6 were significantly positively correlated with disease severity and had high AUC values, suggesting they may be important parameters for early prediction of the progression of mild adenovirus infection to severe disease.

Background/Objectives: This study aimed to characterize the cell-mediated immune (CMI) profile—peripheral lymphocyte subsets, a 14-cytokine panel, and intracellular granzyme B/perforin expression—in children with acute IM compared with age- and sex-matched healthy controls, and to describe its dynamics at symptom resolution in an exploratory paired subset. This is a descriptive, hypothesis-generating study. Methods: We enrolled 40 patients and 50 healthy controls, analyzing peripheral blood T cell subsets, intracellular granzyme B and perforin expression, and serum cytokines. Cross-sectional comparisons were made between the IM group and the healthy control group at diagnosis; in addition, paired samples obtained at clinical symptom resolution were available for a subset of 7 patients and were analyzed as an exploratory longitudinal comparison. Results: Patients showed significantly elevated leukocytes, lymphocytes, and monocytes compared to healthy controls. Immunophenotyping revealed a higher total T cell count, with a lower CD4+ frequency but higher absolute count, and markedly increased CD8+ frequency and count. The B cell frequency was lower, while the NK cell frequency was lower but its absolute count was higher. A broad elevation in measured cytokines was observed, with significantly higher levels of IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-17A, IL-17F, IL-22, TNF-α, TNF-β, and IFN-γ. A cytotoxic phenotype was also more pronounced, with increased proportions of granzyme B- and perforin-expressing cells among CD3+ T cells, CD3+CD8+ T cells, and CD3-CD16/56+ NK cells. Conclusions: In conclusion, pediatric IM is characterized by profound changes in immune cell numbers and proportions, serum cytokine levels, and the expression of cytotoxic-effector molecules. These descriptive findings largely confirm the expected acute anti-EBV response and, in particular, reveal a pronounced coordinated CD8+/NK cytotoxic-effector signature. They warrant prospective, controlled study—ideally including a non-IM febrile/viral comparator—to determine whether such CMI parameters can support diagnosis or grade disease activity.