Glycolipid-dependent interaction between human migration-inhibitory factor and mononuclear phagocytes

Area of Science:

• Immunology
• Cell Biology
• Biochemistry

Background:

• Macrophage glycolipids enhance the response to migration inhibitory factor (MIF) in guinea pigs.
• Gangliosides have been shown to bind MIF, suggesting a receptor function for glycolipids.

Purpose of the Study:

• To investigate the role of glycolipids in mediating the human monocyte response to human MIF.
• To determine if specific glycolipids function as cell surface receptors for MIF on human monocytes.

Main Methods:

• Human peripheral blood monocytes were preincubated with glycolipid-enriched materials and purified glycolipids.
• The response of monocytes to human MIF was measured.
• Affinity purification experiments were conducted using ganglioside-coupled agarose beads.

Main Results:

• Glycolipid-enriched materials from U937 cells and monocytes, as well as purified guinea pig glycolipids and bovine brain gangliosides, enhanced monocyte response to MIF.
• Specific pure gangliosides (GM1, GD1a) and glycolipids from MIF-unresponsive HL-60 cells did not enhance the response.
• Enhancement was temperature-dependent (37°C vs. 4°C) and not due to increased glycolipid uptake.
• Affinity chromatography confirmed the reversible binding of MIF to bovine brain mixed gangliosides.

Conclusions:

• Specific glycolipids, particularly gangliosides, act as cell surface receptors for human MIF on human monocytes.
• The interaction between MIF and its glycolipid receptors is specific and temperature-dependent.