A morphological study of ferritin synthesis in macrophages with ingested ferric hydroxide-potassium polyvinyl sulfate complexes.

Abstract

ABSTRACT. A ferric hydroxide-polyvinyl sulfate colloidal solution (Fe-PVS), prepared by mixing potassium polyvinyl sulfate (PVSK) and ferric hydroxide colloidal solution was used to study ferritin synthesis in rat peritoneal macrophages. The colloidal particles had spherical electron opaque ferric hydroxide cores with diameters of about 250 nm surrounded by radially arranged fibrous PVS molecules. They also had strong negative electric charges.Fe-PVS particles injected into the peritoneal cavity were taken up by the macrophages then disintegrated rapidly. In the phagolysosomes the electron opaque ferric hydroxide cores of Fe-PVS were denuded of their PVS frames then decomposed into small 5-6 nm granules 24 to 48 h after injection. These small granules were released from the lysosomes into the hyaloplasm and the myelin figures were found in the lysosomal vacuoles. No reaccumulation of granules in lysosomes was found even 3 months later.The intracellular distribution of ferritin in macrophages demonstrated by the immunocytochemical method showed a pattern similar to that of the small granules formed by the disintegration of Fe-PVS. This means that in rat peritoneal macrophages that contain ingested Fe-PVS particles ferritin first is synthesized in phagolysosomes by the ferric hydroxide cores that conjugate with apoferritin or protein subunits then they are dispersed into the cytoplasm. Two possible pathways for the biosynthesis of ferritin are discussed.

Endocytosis of cationic iron colloid particles by rat peritoneal macrophages and the ferritin synthesis. A morphological study.

“…In the previous study (9,10), we demonstrated that the anionic iron colloid particles were solely taken up by macrophages. The particles first bound to the cationic groups or receptors on the cell surface, and were then taken into the cytoplasm by phagocytic process resulting in the marked swelling of cells.…”

Endocytic mechanism of macrophages to anionic foreign substances.

“…The results, however, demonstrated that Fe-PVS particles taken into the phagolysosomes of macrophages decomposed quickly. As early as 5 hr after the injection, the ferric hydroxide cores of Fe-PVS were denuded of their PVS frames and decomposed into minute granules in the phagolysosomes (13). Therefore, the labeling of macrophages by Fe-PVS is transient.…”

“…The colloidal solution of Fe-PVS was prepared by mixing ferric hydroxide colloidal solution with potassium polyvinyl sulfate (PVSK, Wako Pure Chemical Indistries Ltd., Osaka) solution as prepared previously (13) . Iron chondroitin sulfate (Fe-ChS, Blutal; for medical use) was donated by Dainippon Seiyaku, Osaka.…”

“…They were then post-fixed in 2 % 0504 for 3 hr, dehydrated through graded ethanol to acetone and embedded in TAAB resin. Ascites fluid of rats were centrifuged for 10 min at 900 rpm and the cell pellets were fixed and sectioned as described previously (13). Tumor ascites cells of mice incubated in tissue culture slides were fixed in 2 % glutaraldehyde for 10 min, post-fixed in 2 % Os04 for 40 min, dehydrated through graded ethanol and embedded directly in TAAB resin.…”

“…The phagocytosis test on scavenger cells with particles carrying distinct anionic (13) and those with chondroitin sulfate molecules (Fe-ChS) had negative electric charges and were excellent tools for this analysis. By using these colloidal particles, we could make clear that macrophages have receptors specific to the substances carrying negative surface charges.…”