目的 了解难治性肺炎支原体肺炎（RMPP）患儿支气管肺泡灌洗液（BALF）中半乳凝素-3与肺炎支原体（MP）载量、气道内中性粒细胞及巨噬细胞细胞免疫的相关性。方法 选取2013年1月至2017年1月住院治疗的64例RMPP患儿作为研究对象。64例RMPP患儿在内科保守治疗的基础上，均在急性期（入院治疗5~7 d）、部分患儿（48例）同时在恢复期（入院治疗10~14 d）进行支气管肺泡灌洗术干预治疗，收集患侧肺叶或肺段BALF 4 mL，离心后采用ELISA检测BALF上清中半乳凝素-3水平，实时荧光PCR（RT-PCR）检测MP载量，离心沉淀的细胞成分在苏木精-伊红染色下计数中性粒细胞及巨噬细胞百分比。6例支气管异物患儿作为对照组。结果 与对照组相比，半乳凝素-3水平在RMPP组急性期及恢复期均明显升高（P < 0.01）；与急性期相比，恢复期明显下降（P < 0.01）。与对照组相比，BALF中中性粒细胞百分比在RMPP组急性期及恢复期均明显升高（P < 0.01）；与急性期相比，恢复期显著下降（P < 0.01）。与对照组相比，RMPP组急性期及恢复期巨噬细胞百分比均显著降低（P < 0.01）；恢复期与急性期相比差异无统计学意义（P > 0.05）。与对照组相比，RMPP组急性期及恢复期BALF中MP载量明显升高；与急性期相比，恢复期显著下降（P < 0.01）。RMPP患儿急性期BALF中半乳凝素-3水平与MP载量和中性粒细胞百分比均呈正相关（分别r_s=0.789、0.726，P < 0.01）。结论 半乳凝素-3参与了RMPP气道炎症反应过程，急性期BALF半乳凝素-3水平与MP载量呈正相关。RMPP是以中性粒细胞增加、巨噬细胞减少为主的细胞免疫炎症损害，半乳凝素-3与RMPP患儿中性粒细胞趋化及管腔浸润密切相关。随着RMPP病情恢复，MP载量呈下降趋势，但恢复期仍未被机体免疫系统完全清除。MP感染可诱发RMPP患者巨噬细胞消耗增加。

Objective To study the correlation of galectin-3 level in bronchoalveolar lavage fluid (BALF) with Mycoplasma pneumoniae (MP) load and cellular immunity of neutrophils and macrophages in the airway in children with refractory MP pneumonia (RMPP). Methods A total of 64 children with RMPP who were hospitalized from January 2013 to January 2017 were enrolled. In addition to the conservative medical treatment, all the 64 children with RMPP were given bronchoalveolar lavage in the acute stage (5-7 days after admission) and 48 out of the 64 children were given bronchoalveolar lavage in the recovery stage (10-14 days after admission). Four milliliters of BALF of the affected lung lobe or segment were collected. ELISA was used to measure the level of galectin-3 in BALF supernatant. RT-PCR was used to measure MP load. Hematoxylin and eosin staining was used to measure the percentage of neutrophils and macrophages. Six children with bronchial foreign bodies were enrolled as the control group. Results The RMPP group had a significantly higher level of galectin-3 in BALF in both the acute and recovery stages than the control group (P < 0.01), and the level of galectin-3 in the acute stage was significantly higher than in the recovery stage (P < 0.01). The RMPP group had a significantly higher percentage of neutrophils in BALF in both the acute and recovery stages than the control group (P < 0.01), and the percentage of neutrophils in the acute stage was significantly higher than in the recovery stage (P < 0.01). The RMPP group had a significantly lower percentage of macrophages in BALF in both the acute and recovery stages than the control group (P < 0.01), but there was no significant difference in the percentage of macrophages between the acute and recovery stages (P > 0.05). The RMPP group had a significantly higher MP load in BALF in both the acute and recovery stages than the control group (P < 0.01), and the MP load in the acute stage was significantly higher than in the recovery stage (P < 0.01). In the children with RMPP, galectin-3 level in BALF in the acute stage was positively correlated with MP load and the percentage of neutrophils (r_s=0.789 and 0.726 respectively; P < 0.01). Conclusions Galectin-3 is involved in the process of airway inflammation in children with RMPP, and the level of galectin-3 in BALF is positively correlated with MP load. RMPP is a cellular immune inflammatory lesion with the increase of neutrophils and the reduction in macrophages. Galectin-3 is closely associated with neutrophil chemotaxis and luminal infiltration in children with RMPP. MP load gradually decreases with the recovery from RMPP, but it is not completely eliminated by the immune system in the recovery stage. MP infection can increase the consumption of macrophages in children with RMPP.