肺炎支原体肺炎患儿支气管肺泡灌洗液T淋巴细胞亚群变化及临床意义

Changes in T Lymphocyte Subsets in Bronchoalveolar Lavage Fluid and Their Clinical Significance in Children with Mycoplasma pneumoniae Pneumonia

摘要: 目的：探讨肺炎支原体肺炎(MPP)患儿支气管肺泡灌洗液(BALF)中T淋巴细胞亚群的变化特征，并分析其临床意义。方法：选取2023年10月~2025年10月本院收治的80例MPP患儿作为研究对象，根据病情严重程度分为轻症组(n = 45)和重症组(n = 35)。采用流式细胞术检测两组患儿BALF中CD3⁺、CD4⁺、CD8⁺ T淋巴细胞百分比；通过二元Logistic回归分析影响因素，并采用向前逐步回归法(纳入α = 0.05，剔除α = 0.10)构建简约预测模型。结果：重症组乳酸脱氢酶(LDH)高于轻症组(P < 0.05)；重症组BALF中CD3⁺、CD4⁺低于轻症组，CD8⁺高于轻症组(P < 0.05)。全变量Logistic回归显示，BALF CD4⁺是重症的保护因素(OR = 0.703, 95% CI: 0.533~0.928, P = 0.013)；BALF CD8⁺ (OR = 1.169, 95% CI: 0.960~1.423, P = 0.121)和LDH (OR = 1.030, 95% CI: 0.996~1.066, P = 0.083)未达统计学显著性。逐步回归筛选后，最终模型仅纳入BALF CD4⁺，构建的简化预测模型为：Logist (P) = 11.725 + (−0.350) × BALF CD4⁺；Hosmer-Lemeshow检验χ² = 4.102，P = 0.848；该模型预测重症MPP的AUC为0.845 (95% CI: 0.762~0.928)，约登指数0.680；以0.438为截断值，敏感度、特异度分别为85.71%、82.22%。结论：MPP患儿BALF中存在T淋巴细胞亚群失衡；BALF CD4⁺可作为评估病情严重程度的独立免疫指标；基于逐步回归构建的简约预测模型避免了过拟合，具有较好的校准度与临床实用性，但仍需多中心外部验证。

Abstract: Objective: To investigate the characteristic changes in T lymphocyte subpopulations in bronchoalveolar lavage fluid (BALF) of children with Mycoplasma pneumoniae pneumonia (MPP) and analyze their clinical significance. Methods: A total of 80 children with MPP admitted to our hospital from October 2023 to October 2025 were selected as study subjects and divided into a mild group (n = 45) and a severe group (n = 35) based on disease severity. Flow cytometry was employed to measure the percentages of CD3⁺, CD4⁺, and CD8⁺ T lymphocytes in the bronchoalveolar lavage fluid (BALF) of both groups. Binary logistic regression analysis was conducted to identify influencing factors, and a simplified predictive model was constructed using forward stepwise regression (with inclusion cutoff at α = 0.05 and exclusion cutoff at α = 0.10). Results: The lactate dehydrogenase (LDH) level was significantly higher in the severe group compared to the mild group (P < 0.05). The BALF levels of CD3⁺ and CD4⁺ were lower in the severe group, while CD8⁺ levels were higher (P < 0.05). Full-variable logistic regression revealed that BALF CD4⁺ was a protective factor for severe disease (OR = 0.703, 95% CI: 0.533~0.928, P = 0.013); BALF CD8⁺ (OR = 1.169,95% CI: 0.960~1.423, P = 0.121) and LDH (OR = 1.030, 95% CI: 0.996~1.066, P = 0.083) showed no statistically significant associations. After stepwise regression screening, the final model included only BALF CD4⁺ cells, yielding a simplified predictive model: Logistic regression equation (P) = 11.725 + (−0.350) × BALF CD4⁺. The Hosmer-Lemeshow test yielded a χ² value of 4.102 with P = 0.848; this model demonstrated an AUC of 0.845 (95% CI: 0.762~0.928) and a Joenson index of 0.680 for predicting severe MPP. Using a cutoff value of 0.438, the sensitivity and specificity were 85.71% and 82.22%, respectively. Conclusion: BALF samples from children with MPP exhibit an imbalance in T lymphocyte subsets; BALF CD4⁺ serves as an independent immunological marker for assessing disease severity; the simplified predictive model developed via stepwise regression avoids overfitting, exhibits good calibration and clinical utility, but requires further multicenter external validation.