Loss of iron from mouse peritoneal macrophages in vitro after uptake of (55fe)ferritin and (55fe)ferritin rabbit antiferritin complexes
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Updated: Aug 13, 2026
Depletion and Reconstitution of Macrophages in Mice
Published on: August 1, 2012
Abstract:
Mouse peritoneal macrophages in culture for 24 h were exposed to horse [(55)Fe]ferritin and rabbit antihorse [(55)Fe]ferritin antibody complex and the amount of (55)Fe in the medium was assayed up to 2 days after the pulse uptake. Cell survival was assayed by photographing the same areas of the tissue culture Petri dish on successive days and by counting cell numbers per unit area. In experiments in which quantitative assay for cell death is negligible, about 10-20% of the iron ingested by pinocytosis or phagocytosis is released to iron-free medium containing either freshly dialyzed or deironized newborn calf serum (10%). Over the 2-day postpulse period, iron loss is linear. This loss of iron to the medium is significantly reduced by adding iron-saturated newborn calf serum in the postpulse recovery period. A significant portion of the iron released to the medium is bound to transferrin. When human serum is used in the tissue culture system, similar quantities (10-25%) of the ingested iron are lost to the medium 2 days after the pulse.
Insights
Macrophages release 10-20% of ingested iron into the medium. This iron loss is reduced when iron-saturated serum is added, and much of the released iron binds to transferrin.
Area of Science:
- Cell Biology
- Iron Metabolism
- Immunology
Background:
- Macrophages play a crucial role in iron homeostasis.
- Understanding iron release from macrophages is vital for studying iron metabolism disorders.
- Ferritin and antibody-antigen complexes are involved in cellular iron uptake.
Purpose of the Study:
- To quantify iron release from mouse peritoneal macrophages after iron-}(55)Fe]ferritin and antibody complex uptake.
- To investigate factors influencing iron release, including serum iron saturation and binding proteins.
- To assess the impact of iron release on macrophage survival.
Main Methods:
- Mouse peritoneal macrophages were cultured and exposed to horse [(55)Fe]ferritin and rabbit antihorse [(55)Fe]ferritin antibody complex.
- Radioactive iron (55)Fe in the culture medium was measured over 2 days.
- Cell survival was assessed by cell counting and imaging.
Main Results:
- Approximately 10-20% of ingested iron was released into iron-free medium over 2 days.
- Iron release was linear over the post-pulse period.
- Iron release was significantly reduced by adding iron-saturated newborn calf serum.
- A portion of the released iron was bound to transferrin.
- Similar iron release (10-25%) was observed when using human serum.
Conclusions:
- Macrophages actively release a portion of ingested iron.
- Serum iron availability influences the rate of iron release.
- Transferrin plays a role in the transport of released iron.
- This study provides insights into macrophage iron handling and potential implications for iron metabolism.
