Chapter 4 - Age-appropriate biology of neonatal neutrophils

Abstract

As sentries of the immune system, neutrophils are vital components of innate immunity and among the first immune cells to respond to and defend against viral, fungal, and bacterial infections. Well-defined phenotypic and functional differences have been extensively documented between fetal/neonatal and adult neutrophils. These cells however have been evolutionarily perfected to detect and respond to inflammatory and/or infectious stimuli within hosts who reside in vastly different environmental conditions. Neonatal neutrophils differ from adult cells in many ways, including the composition of their cell-surface receptors, reduced functional capacity, and decreased concentration of granular microbicidal proteins and enzymes—all of which are essential for pathogen destruction and directly correlated to the infant’s gestational age and clinical status at birth. Consequently the least proficient neutrophils are recovered from the youngest and most critically ill neonates.