Comparative chemiluminescence of neonatal and adult ovine polymorphonuclear leukocytes

Polymorphonuclear leukoctyes (PMN) serve on the first line of the immunological defense of ruminants. However, despite the high morbidity and mortality of neonatal lambs to a wide range of infections there have been no definitive studies undertaken to ascertain whether there might be functional differences in PMN from neonatal lambs when compared to those from adult sheep. To determine whether there were differences in the oxidative respiratory burst of PMN, luminol-dependent chemiluminescence (CL) measurements were made of PMN from lambs at 1 week, 1, 2 and 3 months of age and at the same time from their respective dams. PMN isolated from lambs exhibited significantly lower levels of CL until 2 months of age. At 3 months of age the PMN produced levels of CL equal to that of their dams. As CL mirrors the ability of PMN to efficiently phagocytize and kill pathogens the present findings would suggest that PMN of neonatal lambs during the first 2 months are likely less capable of defending them from pathogenic organisms.