[Non-myeloperoxidase-mediated system activity of neutrophil in newborn infants].
OBJECTIVE
To evaluate the variety of non-myeloperoxidase-mediated system activity of neutrophils in newborns during bacterial infection and the effect of cord plasma on the activation of non-myeloperoxidase-mediated system.


METHODS
An infection model with Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) and a non-infection model with phorbol-12-myristate-13-acetate (PMA) were established to investigate the activation of non-myeloperoxidase-mediated system in neutrophils. According to the intensity of fluorescence, the activation of non-myeloperoxidase-mediated system of neutrophils was detected by flow cytometry (FCM). The blood cells and plasma were separated from cord blood and adult blood and cross-mixed in order to investigate the opsonic activity.


RESULTS
In the non-infection model, the activation of non-myeloperoxidase-mediated system with PMA stimulation in cord blood was lower compared with that in adult blood, the statistical difference was significant (t = 3.378, P < 0.01). In the infection model, the activations of non-myeloperoxidase-mediated system in cord blood were also lower compared with those in adult blood, while the statistical difference could only be found in the model with E. coli stimulation (t = 12.150, P < 0.001). Furthermore the experiments demonstrated that cord plasma could deeply depress the non-myeloperoxidase-mediated system activity with E. coli stimulation. On the contrary, adult plasma could successfully recruit the potential of non-myeloperoxidase-mediated system activity of neutrophils in newborns.


CONCLUSIONS
The function of neonatal neutrophils might not developed very well. As a stimulant, E. coli failed to induce the non-myeloperoxidase-mediated system activity in neonates, which might be related to the lower level of immunoglobulins in cord blood. This result indicated that immunoglobulins played a more important modulating role in bacterial killing during gram-negative bacterial infections.
Zhu
Xiao-dong
XD
Department of Pediatrics, Xinhua Hospital, Shanghai Children's Medical Center, Shanghai Second Medicine University, Shanghai 200092, China.
Chen
Tong-xin
TX
Ji
Ruo-xu
RX
Zhou
Xiao-ling
XL
Wang
Lian-wen
LW
Zhu
Jian-xing
JX
D004926:Escherichia coli / Q000276:immunology; D005312:Fetal Blood / Q000276:immunology; D005434:Flow Cytometry; D006801:Humans; D007231:Infant, Newborn; D009504:Neutrophils / Q000201:enzymology / Q000276:immunology*; D009195:Peroxidase / Q000378:metabolism*; D013211:Staphylococcus aureus / Q000276:immunology
D009195:Peroxidase