NEONATAL GRANULOCYTSIS IS A POSTPARTUM EVENT WHICH IS SEEN IN THE LIVER AS WELL AS IN THE BLOOD

In a recent series of studies, we demonstrated that stress in humans a nd animals, with resultant sympathetic nerve strain, induces severe gr anulocytosis, because granulocytes carry adrenergic receptors on the s urface. Because activated granulocytes produce free radicals and super oxides, they sometimes induce tissue damage if the stress is too stron g or continuous. Human neonates are also known to show high levels of granulocytes in the peripheral blood. In this study, we investigated w hether such neonatal granulocytosis are a stress-associated response a t birth. Both human and mouse materials, before and after birth, were used. The number of leukocytes in the blood, as well as some other fac tors in the serum, were measured. Although levels of granulocytes were found to be low in fetal humans and mice, they increased sharply afte r birth. In parallel with this postpartal granulocytosis, transaminase s in sera increased transiently. In reference to results of a transien t elevation in the levels of catecholamines at birth in mice, all thes e phenomena resemble stress-associated responses. Indeed, fatty liver and hematopoietic destruction in the liver were also observed in mice and humans. At this time, the production of inducible nitric oxide syn thase (iNOS) by granulocytes in the liver was evident. These results s uggest that neonatal granulocytosis is a postpartum event which result s from various stresses (e.g., oxygen stress) at birth. This event may be responsible for such well-known neonatal phenomena as the terminat ion of fetal hematopoiesis in the liver and as neonatal jaundice.