Preterm newborns are provided with triggering receptor expressed on myeloid cells-1.

Triggering receptor expressed on myeloid cells-1 (TREM-1) and soluble fraction (sTREM-1) are useful markers of infection in adults. Neonates, especially preterm infants, are exposed to high risk of sepsis due to the immature immune system and few data are available regarding TREM-1, mainly focused on the soluble form. We therefore decided to investigate the baseline assessment of TREM-1, membrane and soluble receptors, in preterm newborns without clinical or microbiological evidence of infection, in order to precociously measure the possible changes due to sepsis and compare them to the obtained reference values. Fifty-nine newborns were enrolled in the study. Median and Interquartile range of TREM-1 were: in monocytes 96 percent with 71 Mean Fluorescence Intensity (50-94); in PMNs: 80 percent (68-87); soluble TREM-1: 29.1 pg/ml (14.55-103.93). Monocyte expression and soluble TREM-1 concentrations appeared comparable to healthy adults, while not all PMNs expressed this receptor, possibly due to their immaturity. Birth weight negatively correlated with sTREM-1, while there were no statistical significances with gestational age, maternal age, gender, mode of delivery, patent ductus arteriosus, intrauterine growth restriction, premature rupture of membranes and TREM-1 or sTREM-1. We also reported a statistical relationship between monocyte TREM-1 and surfactant administration and between sTREM-1 and antenatal steroid prophylaxis. Even if untrained, the neonatal immune system of preterm newborns is equipped with TREM-1 system, but further studies are needed to evaluate the functionality in newborns.