Rebuck N, Gibson A, Finn A
Department of Paediatrics, University of Sheffield, Children's Hospital, UK.
Clin Exp Immunol. 1995 Jul;101(1):183-9. doi: 10.1111/j.1365-2249.1995.tb02296.x.
The functional deficits of neonatal neutrophils are well documented and are thought to contribute to the increased susceptibility of newborn infants to infection. We measured the adhesion molecules L-selectin, CD11a/CD18 and CD11b/CD18 on neutrophils from the cord blood of term (n = 22) and premature (n = 32) infants using a whole blood method with flow cytometry and quantitative bead standards to enumerate cell surface receptors. We also assayed plasma for the shed form of L-selectin (sL-selectin). Our results suggested that L-selectin expression on term infant neutrophils is lower than that on adult neutrophils (unstimulated and stimulated, both P < 0.001), but that stimulated premature infant cell express higher L-selectin than term infants (P < 0.05); it is possible that this deficiency is caused by physiological changes occurring around the normal time of parturition. We observed reduced sL-selectin in term infants (P < 0.001) compared with adults, and even lower concentrations in premature infants (P < 0.001). The sL-selectin concentrations in plasma may be a reflection of granulopoiesis, which may be reduced in premature infants. Our results showed increased resting neonatal neutrophil expression of CD11b/CD18 compared with adults, and the absence of any neonatal deficit of the ability to up-regulate CD11b/CD18 expression on stimulation. These findings are contrary to previous reports. Further studies suggested that the isolation procedures used in previous reports reduces the capability of the cells to respond to a formyl methionine leucine phenylalanine (fMLP) stimulus. This effect is more marked in neonatal neutrophils, suggesting that the previously reported deficiency is in fact due to the isolation techniques used rather than the cells' innate ability to up-regulate CD11b/CD18 expression. The results of our study lead us to propose that the adhesive function of neonatal neutrophils may be less defective than previously thought.
新生儿中性粒细胞的功能缺陷已有充分记录，被认为是新生儿易受感染的原因之一。我们采用全血法结合流式细胞术和定量微球标准来计数细胞表面受体，测量了足月（n = 22）和早产（n = 32）婴儿脐带血中性粒细胞上的黏附分子L-选择素、CD11a/CD18和CD11b/CD18。我们还检测了血浆中L-选择素的可溶性形式（sL-选择素）。我们的结果表明，足月婴儿中性粒细胞上L-选择素的表达低于成人中性粒细胞（未刺激和刺激后，P均< 0.001），但刺激后的早产婴儿细胞表达的L-选择素高于足月婴儿（P < 0.05）；这种缺陷可能是由正常分娩时间前后发生的生理变化引起的。我们观察到，与成人相比，足月婴儿的sL-选择素降低（P < 0.001），早产婴儿的浓度更低（P < 0.001）。血浆中sL-选择素的浓度可能反映了粒细胞生成情况，早产婴儿的粒细胞生成可能减少。我们的结果显示，与成人相比，新生儿静息中性粒细胞CD11b/CD18的表达增加，且刺激后上调CD11b/CD18表达的能力不存在新生儿缺陷。这些发现与之前的报道相反。进一步研究表明，之前报道中使用的分离程序降低了细胞对甲酰甲硫氨酸亮氨酸苯丙氨酸（fMLP）刺激的反应能力。这种效应在新生儿中性粒细胞中更为明显，表明之前报道的缺陷实际上是由于所使用的分离技术，而非细胞上调CD11b/CD18表达的固有能力。我们的研究结果使我们提出，新生儿中性粒细胞的黏附功能缺陷可能比之前认为的要少。
