Differential staining of neutrophils and monocytes: Surface and cytoplasmic iron-binding proteins

Abstract

Lactoferrin, transferrin, and ferritin were systematically visualized and semiquantified in neutrophils and monocytes/macrophages using indirect immunofluorescence and functional cytochemical techniques. They localized on cell surfaces and within the cytoplasm at the light and electron microscopical levels. In normal subjects, subpopulations of blood neutrophils and monocytes had surface lactoferrin, but little surface transferrin or ferritin was observed on these cells. Most neutrophils had brilliant granular cytoplasmic positivity for lactoferrin; variable fractions of monocytes had weak to moderate diffuse cytoplasmic lactoferrin staining localized most prominently to the cytoplasmic matrix. Most neutrophils had cytoplasmic ferritin, but few had cytoplasmic transferrin, whereas larger subpopulations of monocytes had cytoplasmic staining reactions for both proteins. To analyse maturing cells, the iron nitrilotriacetate-acid ferrocyanide method was adapted for the light microscopical analysis of neutrophils and monocytes/macrophages in soft agar culture. Further, a combined stain that visualizes iron nitrilotriacetate-acid ferrocyanide reactivity and alpha-naphthyl butyrate esterase activity in cells in blood and marrow smears was developed. The relative quantities and subcellular distribution of iron-binding proteins in neutrophils and monocytes/macrophages defined by the present methods can be correlated with biochemical, maturational, and functional properties of these cells.

Iron-Binding Proteins in the Human Vitreous: Lactoferrin and Transferrin in Health and in Proliferative Intraocular Disorders

“…All membranes included in this study yielded positive trans ferrin labeling. Certain types of macro phages, which exhibit immunoreactivity for lactoferrin, have been observed [23], but this is not the case with the macrophages in pre retinal membranes. These cells could be identified in some of the membrane speci mens examined in this study, as described previously [10], but did not yield a positive lactoferrin label.…”

Iron excess affects release of neutrophil extracellular traps and reactive oxygen species but does not influence other functions of neutrophils

“…After binding to its TfR, the diferric complex is endocytosed and STEAP3 ferrireductase reduces iron to Fe 2+ , which is further released into the cytosol by divalent metal transporter 1. 3,18 Given that iron in the bloodstream is bound mainly to transferrin, together with the evidence of the presence of TfR in human neutrophils, 19,20 we investigated the impact of holo-Tf on neutrophil functions. We found that holo-Tf inhibited the release of NETs induced by PMA in neutrophils isolated from healthy individuals.…”