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Receptor binding of lactoferrin by human monocytes
Author(s) -
Birgens Henrik S.,
Hansen Niels Ebbe,
Karle Hans,
Kristensen LarsØstergaard
Publication year - 1983
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/j.1365-2141.1983.tb02113.x
Subject(s) - lactoferrin , transferrin , dissociation constant , receptor , monocyte , chemistry , iron binding proteins , binding site , microbiology and biotechnology , biochemistry , biology , immunology
S ummary . The binding of iron‐saturated 125 I‐lactoferrin to human monocytes was studied at pH 7·4 and 37°C. Monocytes in suspension bound 125 I‐lactoferrin by a reversible, saturable and specific binding indicating the presence of a receptor. The dissociation constant ( K D ) of the binding was estimated at about 4·5 × 10 −9 M and the number of receptors was about 1·6 × 10 6 per monocyte. The affinity of native lactoferrin (20% iron saturated) was only slightly below that of iron‐saturated lactoferrin ( K D about 7·9 × 10 −9 M). Human transferrin, horse cytochrome c and human immunoglobulin G were without inhibitory effect on the binding of 125 I‐lactoferrin. The majority of cell‐bound 125 I‐lactoferrin was dissociable. The dissociation rate was not affected by addition of unlabelled lactoferrin to the dissociation medium. The binding of 125 I‐lactoferrin to adherent mononuclear blood cells showed an about 100‐fold lower affinity ( K D about 2·5 × 10 −7 M) than to cells in suspension, but the specificity of the binding was the same. These results are compatible with the idea that lactoferrin exerts a biological effect mediated by an interaction with cells of the monocyte/macrophage lineage.