Receptor binding of lactoferrin by human monocytes

Area of Science:

• Immunology
• Cell Biology
• Biochemistry

Background:

• Lactoferrin is an iron-binding glycoprotein with diverse biological functions.
• Monocytes are crucial immune cells involved in inflammatory and immune responses.

Purpose of the Study:

• To investigate the binding characteristics of lactoferrin to human monocytes.
• To determine the presence and properties of lactoferrin receptors on monocytes.

Main Methods:

• Radiolabeled 125I-lactoferrin was used to study binding to human monocytes in suspension and adherence.
• Binding affinity (KD) and receptor number were quantified.
• Specificity was assessed using competing ligands.

Main Results:

• Human monocytes exhibit specific, saturable, and reversible binding of 125I-lactoferrin.
• Estimated dissociation constant (KD) for iron-saturated lactoferrin was 4.5 x 10(-9) M, with approximately 1.6 x 10(6) receptors per monocyte.
• Binding affinity was slightly reduced for native lactoferrin and significantly lower for adherent mononuclear cells, but specificity remained consistent.

Conclusions:

• Lactoferrin interacts with human monocytes via specific receptors.
• These findings support the hypothesis that lactoferrin mediates biological effects through interactions with the monocyte/macrophage lineage.