Polymorphonuclear leukocytes of human colostrum. I. Oxidative metabolism and kinetics of killing of radiolabeled Staphylococcus aureus.

Polymorphonuclear leukocytes (PMNLs) were isolated from the colostrum of 57 women. Colostral cells were identified by fluorescent microscopy after supravital staining with acridine orange. Numerous intracellular fat globules within colostral PMNLs were shown by Oil Red O stain and electron microscopy. Oxidative metabolic activity during phagocytosis of opsonized zymosan particles was significantly greater in blood PMNLs compared with colostral PMNLs. The total uptake and killing of [methyl-3H]thymidine-labeled Staphylococcus aureus by blood PMNLs were significantly greater than by colostral PMNLs. Similar defects were produced in blood PMNLs incubated with the lipid fraction of colostrum, but not in those incubated with the aqueous fraction. Surface Fc receptors of colostral PMNLs and blood PMNLs incubated with colostral lipid were significantly reduced in number compared with those of control PMNLs or PMNLs preincubated with the aqueous fraction of colostrum. The metabolic and phagocytic defects of PMNLs from human colostrum appear to be related to colostral substances that alter PMNL surface structure and subsequent function.