The binding of human lactoferrin to mouse peritoneal cells.

Abstract

Human iron-saturated Lf (FeLf), which was labeled with 125I or 50Fe, was found to combine with the membrane of mouse peritoneal cells (MPC) which consisted of 70% macrophages. The following experimental data suggested the involvement of a specific receptor. (a) The binding of FeLf to MPC reached a saturation point. (b) The binding of radioactive FeLf was inhibited by preincubating the cells with cold FeLf but not with human Tf, human aggregated and nonaggregated IgG, or beef heart cytochrome c (c) Succinylation and carbamylation of FeLf resulted in a loss of its inhibiting activity on the binding of radioactive FeLf. Removal of neuraminic acid from FeLf increased its inhibitory activity. (d) The ability of apoLf to inhibit the binding of FeLf to MPC was significantly lower than that of FeLf. The existence of a Lf receptor capable of concentrating Lf released from neutrophils on the membrane of macrophages could explain the apparent blockade of the release of iron from the reticuloendothelial system, which accounts for the hyposideremia of inflammation. A receptor for FeLf was also found on mouse peritoneal lymphocytes. The affinity constant of FeLf for both lymphocytes and macrophages was 0.9 X 12(6) liter/mol. Howerver, macrophages bound three times more FeLf molecules (20 X 10(6)) per cell than did lymphocytes (7 X 10(6)).

Apoptotic human cells inhibit migration of granulocytes via release of lactoferrin

“…Lactoferrin has been shown previously to bind to receptors on mononuclear phagocytes and to inhibit proinflammatory responses via NF-κB (39,54,55). Taken together with the evidence that apoptotic cells can suppress proinflammatory responses of mononuclear phagocytes and can elicit antiinflammatory responses by these cells (10,11), our results indicate that it is now reasonable to suspect that these effects are mediated, at least in part, by lactoferrin produced by apoptotic cells.…”

Ceruloplasmin expression by human peripheral blood lymphocytes: A new link between immunity and iron metabolism

“…There is now compelling evidence that lymphocytes are involved in the regulation of Fe metabolism, namely through the synthesis or specific binding of several "Fe-related proteins" [42][43][44][45]. In this context, lymphocyte CP expression gives additional support to the original postulate from De Sousa et al addressing a role for lymphocyte circulation in the regulation of Fe load [19] and establishes an additional link between immune system and Fe homeostasis.…”

Primary Structure of the Glycans from Human Lactotransferrin

“…In fact, it has been shown that the serotransferrins recognize specifically membrane receptors of the reticulocytes [50], that ovotransferrins recognize embryo bird cells [5 11 and that the lactotransferrins recognize the membrane receptors of human enterocytes [52]. The recognition of human lactotransferrin by the membrane receptors of the macrophages has been described by Van Snick et al [53]. This recognition may probably be mediated by the fucose residues, since Shepherd et al [54] have recently described the presence of fucose receptors on rat macrophages.…”