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The binding of human lactoferrin to mouse peritoneal cells
The Journal of Experimental Medicine
|December 1, 1976
Summary
Researchers discovered a specific receptor for human iron-saturated lactoferrin (FeLf) on mouse macrophages and lymphocytes. This finding helps explain iron regulation during inflammation and identifies a potential target for therapeutic interventions.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Lactoferrin (Lf) plays a role in iron transport and immune modulation.
- Hyposideremia (low iron) is characteristic of inflammation, linked to iron sequestration by the reticuloendothelial system.
Purpose of the Study:
- To investigate the mechanism of human iron-saturated lactoferrin (FeLf) binding to mouse peritoneal cells (MPC).
- To identify and characterize the receptor involved in FeLf-macrophage interactions.
Main Methods:
- Radiolabeling of FeLf (with 125I or 50Fe) for binding assays.
- Competition assays using modified FeLf, transferrin, and other proteins.
- Characterization of FeLf binding kinetics and receptor affinity.
Main Results:
- FeLf binding to MPC (70% macrophages) exhibited saturation, indicating specific receptor involvement.
- Binding was inhibited by cold FeLf but not by transferrin or IgG, suggesting receptor specificity.
- Chemical modifications of FeLf (succinylation, carbamylation) reduced binding activity, while neuraminidase treatment enhanced it.
- Apo-lactoferrin showed significantly lower inhibitory activity than FeLf.
- FeLf receptors were identified on both macrophages and lymphocytes, with macrophages binding more FeLf molecules per cell.
Conclusions:
- A specific lactoferrin receptor exists on macrophages and lymphocytes.
- This receptor may mediate the uptake of lactoferrin released from neutrophils.
- The receptor mechanism could explain iron blockade in inflammation and associated hyposideremia.