Addition Of Lactoferrin Research Articles

Hydroxylation of phenylalanine by the hypoxanthine-xanthine oxidase system.

When phenylalanine was treated with hypoxanthine and xanthine oxidase in citrate buffer (pH 5.5), p-tyrosine, m-tyrosine and o-tyrosine were identified as hydroxylated products. Addition of superoxide dismutase or catalase to this system prevented the hydroxylation, implying that superoxide radical and hydrogen peroxide were essential intermediates in the hydroxylation reaction. Chemical scavengers of hydroxyl radical (·OH) prevented the hydroxylation. In particular, 50 mM potassium iodide completely prevented the hydroxylation. The addition of lactoferrin or Fe3+ accelerated the hydroxylation of phenylalanine. These results indicate that the hydroxylation of phenylalanine is caused by ·OH formed in a hypoxanthine-xanthine oxidase system.

A Monokine Regulates Colony-Stimulating Activity Production by Vascular Endothelial Cells

Human umbilical vein endothelial cells were cultured in supernatants of peripheral blood monocytes that had been cultured for 3 days with and without lactoferrin. Colony-stimulating activity (CSA) was measured in supernatants of the endothelial cell cultures and appropriate control cultures using normal, T-lymphocyte-depleted, phagocyte-depleted, low-density bone marrow cells in colony growth (CFU-GM) assays. Monocyte-conditioned medium contained a nondialyzable, heat labile factor that enhanced 4-15--fold the production of CSA by endothelial cells. The addition of lactoferrin to monocyte cultures reduced the activity of this monokine by 69%. Lactoferrin did not inhibit CSA production by monokine-stimulated endothelial cells. Therefore, vascular endothelial cells are potent sources of CSA, the production of CSA by these cells is regulated by a stimulatory monokine, and the production and/or release of the monokine is inhibited by lactoferrin, a neutrophil-derived putative feedback inhibitor of granulopoiesis. Inasmuch as a similar monokine is known to stimulate CSA production by fibroblasts and T lymphocytes, we suggest that mononuclear phagocytes play a pivotal role in the regulation of granulopoiesis by recruiting a variety of cell types to produce CSA.

A monokine regulates colony-stimulating activity production by vascular endothelial cells

Human umbilical vein endothelial cells were cultured in supernatants of peripheral blood monocytes that had been cultured for 3 days with and without lactoferrin. Colony-stimulating activity (CSA) was measured in supernatants of the endothelial cell cultures and appropriate control cultures using normal, T-lymphocyte-depleted, phagocyte-depleted, low- density bone marrow cells in colony growth (CFU-GM) assays. Monocyte- conditioned medium contained a nondialyzable, heat labile factor that enhanced 4–15--fold the production of CSA by endothelial cells. The addition of lactoferrin to monocyte cultures reduced the activity of this monokine by 69%. Lactoferrin did not inhibit CSA production by monokine-stimulated endothelial cells. Therefore, vascular endothelial cells are potent sources of CSA, the production of CSA by these cells is regulated by a stimulatory monokine, and the production and/or release of the monokine is inhibited by lactoferrin, a neutrophil- derived putative feedback inhibitor of granulopoiesis. Inasmuch as a similar monokine is known to stimulate CSA production by fibroblasts and T lymphocytes, we suggest that mononuclear phagocytes play a pivotal role in the regulation of granulopoiesis by recruiting a variety of cell types to produce CSA.

Regulation of colony-stimulating activity production. Interactions of fibroblasts, mononuclear phagocytes, and lactoferrin.

Neonatal skin fibroblasts were cultured in supernatants of peripheral blood monocytes that had been cultured with and without lactoferrin. Granulocyte-monocyte colony-stimulating activity (CSA) was measured in supernatants of the fibroblast cultures with normal T lymphocyte-depleted, phagocyte-depleted, low density bone marrow target cells in colony growth (colony-forming unit granulocyte/macrophage) assays. Monocyte-conditioned medium contained a nondialyzable factor that enhanced by 17-50-fold the production of CSA by fibroblasts. The addition of lactoferrin to monocyte cultures reduced the activity of this monokine by 75-100%. Lactoferrin did not inhibit CSA production by monokine-stimulated fibroblasts. We conclude that under appropriate conditions human fibroblasts are potent sources of CSA, that the production of CSA by these cells is regulated by a stimulatory monokine, and that the production and or release of the monokine is inhibited by lactoferrin, a neutrophil-derived putative feedback inhibitor of granulopoiesis. We propose that the major role of mononuclear phagocytes in granulopoiesis is played not by producing CSA, but by recruiting other cells to do so, and that in the steady state, feedback regulation of neutrophil production may occur as a result of a mechanism that inhibits the recruitment phenomenon.

Iron Absorption From Human Milk, Simulated Human Milk, and Proprietary Formulas

Studies from our laboratory have shown that iron is better absorbed from human milk than from cow milk and that human milk can provide insufficient iron for infants during their first year. We compared iron availability from human milk with that from other formulas and determined the factors responsible for its superiority. Adults were fed 100 ml of human milk, simulated human milk, simulated human milk containing added lactoferrin, two commercial formulas containing iron, 12 mg/qt, and human milk that had been boiled. The simulated human milk resembled human milk in concentration of protein, fat, carbohydrate, iron, total minerals, calcium, and phosphorus. Iron 59 was added to each feeding and iron incorporation into RBCs was determined 14 days after each feeding. Percent iron absorption was highest from human milk and lowest from the commercial formulas. The simulated human milk supported a 9.0% absorption; addition of lactoferrin reduced this to 4.7%. Net iron absorption was 0.12 mg/liter from human milk and 0.40 and 0.37 mg/liter from the iron-enriched commercial formulas. Absorption of iron from boiled human milk was the same as from the unboiled milk. This study confirms the unique ability of human milk to promote iron absorption. Simple manipulation of the protein, fat, lactose, calcium, phosphorus, or lactoferrin content of proprietary milk did not reproduce the iron absorption demonstrated with human milk.

IRON ABSORPTION FROM HUMAN MILK, SIMULATED HUMAN MILK AND PROPRIETARY FORMULAS

Studies from our laboratory have shown that iron is better absorbed fron human milk than from cow milk and can provide sufficient iron for infants during their first year. This study was designed to compare iron availability from human milk with other formulas and determine factors responsible for its superiority. Adults were fed 100 ml of the following: human milk (HM), simulated human milk (SHM), simulated human milk containing added lactoferrin (SHM-L) and 2 commercial formulas (CF) containing iron, 12 mg/qt. The SHM resembled HM in concentration of protein, fat, carbohydrate, iron, total minerals, calcium and phosphorus. Fe59 was added to each feeding and iron incorporation into red cells was determined 14 days after each feed. Iron absorption was highest from HM (15.7%) and lowest from one of the CF (1.7%). The SHM supported a 9.3% absorption; addition of lactoferrin reduced this to 4.7%. Net iron absorption was 0.12 mg/L from HM and 0.20 and 0.37 mg/L from the iron enriched CF's. This study demonstrates that the enhanced iron absorption from HM is not a simple result of its gross composition or the presence of lactoferrin, and that HM, with only 6% of the iron of a leading CF, can provide as much as 60% of the iron derived from such a proprietary milk.