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Published on: October 1, 2015
Bovine lactoferrin stimulates the phagocytic activity of human neutrophils: identification of its active domain
H Miyauchi1, S Hashimoto, M Nakajima
1Nutritional Science Laboratory, Morinaga Milk Industry Co., Ltd., Kanagawa Prefecture, Japan.
Insights
Bovine lactoferrin (bLF) significantly boosts human neutrophil phagocytic activity. This enhancement is linked to its lactoferricin (bLFcin) domain, suggesting dual action mechanisms.
Area of Science:
- Immunology
- Biochemistry
Background:
- Neutrophil phagocytosis is crucial for innate immunity.
- Bovine lactoferrin (bLF) is a multifunctional milk protein.
Purpose of the Study:
- To investigate the effect of bLF on human neutrophil phagocytic activity.
- To identify the specific domain of bLF responsible for this activity.
Main Methods:
- Human neutrophils were incubated with FITC-labeled latex beads.
- Phagocytosis was quantified using flow cytometry.
- Bovine lactoferrin (bLF) and its hydrolysates/fragments were used.
Main Results:
- bLF enhanced neutrophil phagocytosis in a dose-dependent manner (50-250 µg/ml).
- The stimulatory effect persisted after pepsin hydrolysis and neutrophil washing.
- Bovine lactoferricin (bLFcin), a fragment of bLF, was identified as the active component.
- Pretreatment of latex beads with bLF also enhanced their uptake.
Conclusions:
- Bovine lactoferrin (bLF) effectively enhances human neutrophil phagocytosis.
- The bLFcin domain is responsible for this activity.
- bLF may act through direct binding to neutrophils and/or opsonin-like properties.
Abstract:
Bovine LF (bLF) at concentrations in the range of 50-250 micrograms/ml enhanced the phagocytic activity of human neutrophils as determined by measuring the incorporation of FITC-labeled latex beads by flow cytometry. The stimulatory effect of bLF was not abrogated by hydrolysis with pepsin. Bovine lactoferricin (bLFcin), which is a bactericidal fragment purified from a pepsin hydrolysate of bLF (bLFH), also enhanced the phagocytic activity, whereas, in contrast, the fraction of bLFH depleted of bLFcin showed no stimulatory effect. The phagocytosis-enhancing activity of bLF still remained after washing the neutrophils, following exposure to bLF. Also, bLF pretreatment of the latex beads stimulated their uptake. These results demonstrate that bLF is effective in promoting the phagocytic activity of human neutrophils. This activity appears to be due to its bLFcin domain and may involve dual mechanisms of direct binding to neutrophils and opsonin-like activity.
