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Influence of lactoferrin on the function of human polymorphonuclear leukocytes and monocytes
Abstract:
Polymorphonuclear leukocytes (PMN) exposed to highly purified human lactoferrin (from colostrum) exhibit an increased random motility (at least 2.5-fold) and are primed to produce more superoxide [12.1 +/- 1.2 nmol O2-/min/10(6) PMN preincubated with lactoferrin (0.5 mg/ml) against 6.4 +/- 2.3 with cells without lactoferrin after FMLP stimulation]. The action of lactoferrin seemed to be specific, because it could be abolished by simultaneous addition of antilactoferrin antibody. Addition of transferrin and iron salts to PMN was without effect. Between iron-poor and iron-saturated lactoferrin there was no difference in influence on PMN function except for a higher FMLP stimulated superoxide production by iron-saturated lactoferrin. Aggregation, degranulation (beta-glucuronidase, lysozyme), and bacterial killing were not influenced by lactoferrin. Incubation of monocytes and monocyte-derived macrophages with lactoferrin did not alter their motility or their superoxide production rates. Our findings indicate that PMN become more effective after exposure to lactoferrin by having a greater motility and producing superoxide at a faster rate.
Insights
Human lactoferrin enhances polymorphonuclear leukocyte (PMN) function. Lactoferrin increases PMN motility and superoxide production, making these immune cells more effective.
Area of Science:
- Immunology
- Biochemistry
Background:
- Lactoferrin, a protein found in secretions like colostrum, plays a role in innate immunity.
- Its specific effects on human immune cell function require further elucidation.
Purpose of the Study:
- To investigate the impact of highly purified human lactoferrin on polymorphonuclear leukocyte (PMN) and monocyte functions.
- To determine if lactoferrin influences PMN motility, superoxide production, aggregation, degranulation, and bacterial killing.
Main Methods:
- Human lactoferrin was purified from colostrum.
- PMNs and monocytes were incubated with lactoferrin.
- Cellular functions including random motility, superoxide production (FMLP-stimulated), aggregation, degranulation (beta-glucuronidase, lysozyme release), and bacterial killing were assessed.
Main Results:
- Lactoferrin significantly increased PMN random motility (at least 2.5-fold) and primed them for enhanced superoxide production.
- Lactoferrin's effects were specific, as they were blocked by antilactoferrin antibody and unaffected by transferrin or iron salts.
- Iron-saturated lactoferrin showed a higher rate of FMLP-stimulated superoxide production compared to iron-poor lactoferrin.
- Lactoferrin did not influence PMN aggregation, degranulation, or bacterial killing.
- Monocyte and macrophage motility and superoxide production remained unaltered by lactoferrin exposure.
Conclusions:
- Human lactoferrin enhances PMN effectiveness by increasing motility and accelerating superoxide production rates.
- Lactoferrin's immunomodulatory effects appear specific to PMNs and do not extend to monocytes or macrophages in terms of motility or superoxide generation.