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Differential iron transport into phagosomes isolated from the RAW264.7 macrophage cell lines transfected with Nramp1 Gly169 or Nramp1 Asp169
Author(s) -
Kuhn Donald E.,
Baker Beth D.,
Lafuse William P.,
Zwilling Bruce S.
Publication year - 1999
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1002/jlb.66.1.113
Subject(s) - phagosome , transfection , phagocytosis , biology , macrophage , cell culture , microbiology and biotechnology , in vitro , biochemistry , genetics
The transport of iron by RAW264.7 macrophage cell lines transfected with either Nramp1 Gly169 (resistant) or Nramp1 Asp169 (susceptible) alleles was assessed. We found no difference between resistant and susceptible cells in the rate of Fe import or export when Fe transport was measured in intact cells. In contrast, the rate of Fe import by latex‐bead phagosomes isolated from resistant cells was more than double the rate by latex‐bead phagosomes from susceptible cells. Similarly, phagosomes isolated from resistant cells that had been pre‐labeled with 55 Fe‐citrate before phagocytosis contained up to four times as much Fe as the corresponding phagosomes from susceptible cells. Phagocytosis of Mycobacterium avium was accompanied by an increase in the production of hydroxyl radicals by Nramp1 Gly169 ‐transfected macrophages but not by macrophages transfected with the susceptible allele. These results are consistent with the hypothesis that Nramp1 functions to transport Fe into the bacterium‐containing phagosome where it serves as a catalyst for the Haber‐Weiss reaction, which accounts for the increased capacity of these cells to limit mycobacterial growth. J. Leukoc. Biol. 66: 113–119; 1999.