INCREASED LEUKOCYTE ALKALINE PHOSPHATASE IN SICK NEONATES

Abstract

Alkaline phosphatase (LAP) and myeloperoxidase (MPO) were evaluated in polymorphonuclear leukocytes (PMNs) from neonates using a computer-assisted cytospectrophotometer. This method allowed quantitative enzyme determinations within each PMN. Population distributions were determined for 100 individual cells. Of the 10 infants studied, 8 were ill, 3 with congenital pneumonia and 5 without proven infection, and 2 were well pre-term infants. PMNs were obtained from all during the first week of life and from 5 during the third week, as well. The 8 ill infants showed a broad distribution of LAP activity in their PMNs in the first week of life, with 75.4±25.2% (x̄±S.D.) of PMNs having LAP activity greater than the 95th percentile of our adult controls. By the third week of life, the percent of PMNs had significantly diminished to 35.6±33.9% (x̄±S.D.) (p < .05). The 2 well pre-term infants in the first week of life had only 7±4% (x̄±S.D.) of PMNs with activity greater than the 95th percentile for adult controls. The distribution of MPO activity did not differ from adult controls in any infant.In summary, we found increased PMN LAP activity in the first week of life in sick neonates with and without infection as compared with adults and well neonates. Decreasing LAP activity in the third week of life corresponded with clinical improvement. Thus, differences in intracellular LAP activity appear to be due to pathologic rather than maturational processes.