Receptors for Transferrin on Human Neutrophils

ABSTRACT

The kinetics of ⁵⁹FeTf binding to the neutrophil membrane receptors was evaluated. Results showed that polymorphonuclear leucocytes (PMN) possess membrane receptors not only for lactoferrin, but also for transferrin. Receptor binding experiments showed biphasic patterns with two peaks of saturation: 16% and 30% of the specific binding to the cell membrane receptors. The Scatchards analysis evaluated two types of binding sites: One—with high affinity and low capacity: Ka1 = 9.88 × 10⁸ M⁻¹and 40 300 receptors/cell, (y₁ = 9.92 - 0.182.x, n=2, r= -1, p<0.001), and second—with low affinity and high capacity: Ka₂ = 12.54 × 10⁹ M⁻¹ and 129 000 receptors/cell (y₂ = 4.04 - 0.21.x, n =4, r = -0.999, p<0.001). It is probably that the transferrin receptors on the neutrophil membrane have the function to ensure a controlled pathway of Fe²+ transfer to prevent an iron overload, thus to accomplish an antioxidative protection of the cell membrane.

Keyword:

• transferrin
• Receptors
• neutrophils