目的 探讨淋巴细胞亚群绝对数对重症肺炎支原体肺炎（severe mycoplasma pneumonia，SMPP）患儿早期预警的价值及支气管镜检查特点，从而为SMPP的早期诊断提供有价值的参考。 方法 本研究纳入了102例肺炎支原体肺炎（mycoplasma pneumoniae pneumonia， MPP）患儿，其中普通MPP（54例）和SMPP患儿（48例），收集并比较两组患儿淋巴细胞亚群、临床特点及实验室指标。并进一步将患儿分为黏液栓痰组和非黏液栓痰组，比较其淋巴细胞亚群特征。 结果 淋巴细胞亚群CD3⁺CD19 ^- T、CD4⁺T、CD3 ^- CD19⁺B、CD3 ^- /CD16⁺CD56⁺ NK细胞绝对数水平两组比较差异均有统计学意义（P < 0.05）。淋巴细胞亚群CD3⁺、CD4⁺、CD19⁺、CD56⁺绝对计数与铁蛋白、LDH、CRP、D-D均呈负相关（P < 0.05）。多因素logistic回归模型分析发现CD3⁺CD19 ^- T、CD4⁺T、CD3 ^- CD19⁺B、CD3 ^- /CD16⁺ CD56⁺ NK绝对计数是SMPP的独立危险因素。ROC曲线分析显示，CD3⁺CD19 ^- T、CD4⁺T、CD3 ^- CD19⁺B、CD3 ^- /CD16⁺ CD56⁺ NK细胞绝对计数鉴别诊断SMPP和普通MPP的曲线下面积分别为0.711、0.887、0.856、0.860，其敏感度分别为47.4%、80.8%、82.1%、92.3%，特异度分别为89.7%、87.2%、75%、70.5%。4种淋巴细胞亚群的组合ROC曲线面积为0.983，敏感度为97.4%，特异度为92.3%。SMPP组行支气管镜比例、镜下黏液栓痰高于普通MPP组（P < 0.05）。黏液栓痰组CD3?CD19?T细胞及CD4?T细胞绝对数显著低于非黏液栓痰组，且CD8?T细胞百分比升高、CD4?/CD8?比值降低（P < 0.05）。 结论 外周血CD3⁺CD19 ^- T、CD4⁺T、CD3 ^- CD19⁺B、CD3 ^- /CD16⁺ CD56⁺ NK细胞绝对数预测SMPP具有较高的敏感性以及特异性，可作为SMPP的潜在预测指标。SMPP镜下发生黏液栓比例高，需积极行支气管镜治疗；T细胞亚群失衡与支气管镜下黏液栓形成显著相关。

Objective To investigate the value of the absolute number of lymphocyte subpopulations as an early warning indicator for children with SMPP（severe mycoplasma pneumonia， SMPP） and to analyze the characteristics observed via bronchoscopy， thereby providing a valuable reference for the early diagnosis of SMPP. Methods This study included 102 children with Mycoplasma pneumoniae pneumonia （MPP）， comprising 54 cases of common MPP and 48 cases of SMPP. The lymphocyte subpopulations， clinical characteristics， and laboratory indicators were analyzed. Results There were statistically significant differences between the two groups in the absolute number levels of lymphocyte subpopulations CD3⁺CD19^-T， CD4⁺T， CD3^-CD19⁺B， CD3^-/CD16⁺CD56⁺NK cells （P < 0.05）. The absolute numbers of CD3⁺CD19^-T， CD4⁺T， CD3^-CD19⁺B， and CD3^-/CD16⁺CD56⁺NK cells showed negative correlations with serum ferritin， LDH， CRP， and D?D， respectively （P < 0.05）. Multifactorial logistic regression analysis identified the absolute numbers of CD3⁺CD19^-T， CD4⁺T， CD3^-CD19⁺B， and CD3^-/CD16⁺CD56⁺NK cells as independent risk factors for severe Mycoplasma pneumoniae pneumonia （SMPP）. ROC analysis demonstrated that the areas under the curve for diagnosing SMPP based on the absolute numbers of CD3⁺CD19^-T， CD4⁺T， CD3^-CD19⁺B， and CD3^-/CD16⁺CD56⁺NK cells were 0.711， 0.887， 0.856， and 0.860， respectively， with sensitivities of 47.4%， 80.8%， 82.1%， and 92.3%， and specificities of 89.7%， 87.2%， 75%， and 70.5%， respectively. The combined ROC curve of the four lymphocyte subsets had an area of 0.983， with a sensitivity of 97.4% and specificity of 92.3%. The proportions of bronchoscopy findings and microscopic examination of mucus plugs in the SMPP group were significantly higher than those in the ordinary MPP group （P < 0.05）. In the mucoid plug subgroup， the absolute numbers of CD3?CD19?T cells and CD4?T cells were significantly lower compared to the non?mucoid plug subgroup， while the percentage of CD8?T cells increased and the CD4?/CD8? ratio decreased （all P < 0.05）. Conclusions The absolute number of CD3⁺CD19^-T， CD4⁺T， CD3^-CD19⁺B， and CD3^-/CD16⁺CD56⁺NK cells in peripheral blood serves as a highly sensitive and specific predictor of small airway mucus plugging phenomenon （SMPP） and can thus be utilized as a potential biomarker for SMPP. Microscopic analysis under SMPP conditions reveals a high prevalence of mucus plugs， necessitating proactive bronchoscopic intervention. Furthermore， the significant imbalance in T cell subpopulations is strongly correlated with the formation of mucus plugs observed during bronchoscopy.