Uptake and release of transferrin and iron by mitogen-stimulated human lymphocytes
- 1 September 1983
- journal article
- research article
- Published by Wiley in British Journal of Haematology
- Vol. 55 (1), 93-101
- https://doi.org/10.1111/j.1365-2141.1983.tb01227.x
Abstract
Phytohaemagglutinin stimulation of human peripheral blood lymphocytes resulted in the expression of transferrin receptors and the uptake of iron into the cells. As assessed from the resistance of the 125I label to pronase, transferrin was rapidly bound and internalized at 37°C, while at 4°C 85% of the 125I label remained on the cell surface and was degraded by the pronase. Over 94% of the 125I label associated with and subsequently released from the cells was acid precipitable, indicating that transferrin was not degraded during its uptake and release. After reincubation for 1 h in fresh medium 70% of the cell associated 125I-transferrin was released. In contrast, less than 30% of the 59Fe was released, showing that iron was removed from transferrin and retained by the cells. Concentration dependent binding of 125I-transferrin estimated at 37°C occurred with an apparent Ka of 5·7±1·1 × 107l mol−1 (mean ± SD, n= 4) indicating little variation between cells from different individuals, although the number of transferrin molecules associated with the cells varied greatly from 6·2 × 104/cell to 1·4 × 105/cell. The rate of iron uptake from 59Fe and 125I labelled transferrin at 37°C by the cells from different subjects was also very variable, with a range between 0·46 and 2·27 pg Fe/min/106 cells (n= 6). However, iron uptake did not correlate with the amount of transferrin bound. This suggests that transferrin uptake and the release of iron from the transferrin to the interior of the cell are controlled independently.This publication has 27 references indexed in Scilit:
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