早产儿中性粒细胞活性氧代谢的研究

目的：该研究通过对于不同胎龄新生儿中性粒细胞活性氧代谢水平的检测研究，以了解新生儿中性粒细胞功能发育成熟的过程，并探讨早产儿对于细菌高易感性的部分原因。方法：选择早产儿35例，分为胎龄32周以下和33～36周两组，并选择足月新生儿23例作为对照组。在新生儿出生后取脐静脉血进行体外实验，分别以金黄色葡萄球菌和大肠杆菌刺激诱导呼吸爆发后用超氧阴离子特异性探针氢化溴乙非锭进行细胞内染色，通过流式细胞仪检测中性粒细胞超氧阴离子阳性细胞比率和产生水平；同时对两组不同胎龄早产儿细菌感染实际发生情况进行比较。结果：胎龄32周以下早产儿超氧阴离子阳性中性粒细胞比率与胎龄32周以上早产儿和足月新生儿相比差异有显著性，呈明显低下状态［金黄色葡萄球菌:（79.4±8.6）% vs （89±6.1）% vs （91.3±3.8）%,F＝18.05,P＜0.01；大肠杆菌: （78.2±7.8）% vs （89.3±5.3）% vs （92±4.1）%,F＝28.3, P＜0.01)］；而且阳性率和早产儿胎龄大小密切相关(y＝2.66 x ，P＜0.01)；但3组不同胎龄的新生儿活性氧代谢阳性细胞超氧阴离子产生水平之间的差异无显著性。临床观察发现小胎龄早产儿组全身性细菌感染实际发生率高于大胎龄组早产儿。结论：新生儿中性粒细胞细菌诱导活性氧代谢的总体能力直接和新生儿成熟度相关，在胎龄小于32周早产儿中处于明显低下状态，并随着胎龄的增加逐渐成熟。早产儿中性粒细胞活性氧代谢水平的总体低下是导致早产儿细菌感染高易感性的重要原因之一。［中国当代儿科杂志，2007，9（4）：355-357］

Decreased active oxygen metabolism in neutrophils of preterm infants

OBJECTIVE: To investigate the influence of neonatal maturity on active oxygen metabolism in neutrophils and possible causes of a high susceptibility to bacterial infection in preterm infants. METHODS: Thirty-five preterm infants born at a gestation age of 26-32 weeks (< or =32 weeks group, n=15) and at 33-36 weeks (> 32 weeks group, n=20) and 23 full-term infants (control group) were enrolled in this study. The samples of whole cord blood from the two preterm groups and the control group were stimulated in vitro with live bacteria,Staphylococcus aureus ( S. aureus) and Escherichia coli (E. coli) and stained with hydroethedine, an indicator of superoxide. The percentage of neutrophils which produced superoxide and the mean fluorescence intensity for superoxide production were measured by flow cytometry. The incidence of bacterial infection during hospital stay was compared between the two preterm groups. RESULTS: Under S. aureus or E. coli stimulation, the percentage of neutrophils which produced superoxide in the < or =32 weeks group was significantly lower than that of the > 32 weeks group and the control group (P < 0.01). The percentage of neutrophils which produced superoxide was closely related to gestational age in preterm infants ( y=2.66 x, P < 0.01).There were no significant differences in the blood level of superoxide production in neutrophils among the three groups. The incidence of bacterial infection during hospital stay in the < or =32 weeks group (40%) was significantly higher than that the > 32 weeks group (10%) (P < 0.05). CONCLUSIONS: The capability of active oxygen metabolism in neutrophils was significantly related to the gestational age in preterm infants. The decreased capability of active oxygen metabolism might be contributed to a higher susceptibility to bacterial infection in preterm infants.