Receptor recognition of maleyl-albumin induces chemotaxis in human monocytes.
We demonstrate here that the exceptionally active maleyl-albumin receptor of human monocytes functions in vitro as a chemoattractant receptor. Chemotaxis of human monocytes occurs at an effective median dose of 3-4 microM maleyl-albumin, a concentration representing 1% of the total albumin in the adult human. Computerized analyses by LIGAND of the saturable binding of maleyl-albumin to human monocytes reveal two classes of binding sites, described by dissociation constants of 37 nM and 5.3 microM with maximal binding of 1.6 and 23 pmol maleyl-albumin/mg cellular protein, respectively. Chemotaxis of human monocytes thus occurs at concentrations of maleyl-albumin promoting binding to the lower-affinity sites. We propose that conformational isomers of albumin that are chemotactic may form in vivo and that albumin, in addition to receptor-independent plasma transport functions, may also play an important role in the receptor-mediated recruitment and accumulation of phagocytic cells at sites of inflammation and injury.
D000418:Albumins / Q000378:metabolism / Q000494:pharmacology*; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002634:Chemotaxis, Leukocyte / Q000187:drug effects*; D006801:Humans; D009000:Monocytes / Q000502:physiology*; D017457:Receptors, Albumin; D011956:Receptors, Cell Surface / Q000502:physiology*; D012710:Serum Albumin, Bovine
D000418:Albumins; D017457:Receptors, Albumin; D011956:Receptors, Cell Surface; C049877:maleylalbumin; C049878:maleylalbumin receptor; D012710:Serum Albumin, Bovine