Specific inhibition of Escherichia coli ferrienterochelin uptake by a normal human serum immunoglobulin.
Normal human serum contains an enterochelin-specific antibody which presumably acts with transferrin to hinder iron assimilation by enterochelin-producing pathogens. This antibody can be isolated from serum by sodium sulfate fractionation or affinity chromatography by employing an enterochelin-derived ligand (2,3-dihydroxy-N-benzoyl-L-serine) attached to aminohexyl Sepharose 4B. In assays of iron uptake by whole cells, the antibody inhibited enterochelin-directed uptake but not that mediated by citrate or ferrichrome. Also, the growth stimulatory effect of enterochelin on an Ent- strain of Escherichia coli was blocked by the immunoglobulin. This antibody has a high affinity for enterochelin; various elution procedures employing high salt concentrations and low pH failed to remove it from affinity columns. Elution with 3 M sodium thiocyanate or 13 mM 2,3-dihydroxybenzoic acid proved successful. Two pieces of evidence indicate the enterochelin-specific antibody is primarily of the immunoglobulin A (IgA) isotype. It could be removed from serum with goat antihuman IgA and was present only in sodium sulfate fractions of serum known to contain IgA.
D000907:Antibodies, Bacterial; D001692:Biological Transport; D004758:Enterobactin / Q000276:immunology*; D004926:Escherichia coli / Q000276:immunology* / Q000378:metabolism; D005290:Ferric Compounds / Q000276:immunology / Q000378:metabolism; D005291:Ferrichrome / Q000378:metabolism; D006801:Humans; D007070:Immunoglobulin A; D007501:Iron / Q000378:metabolism; D012694:Serine / Q000031:analogs & derivatives*
D000907:Antibodies, Bacterial; D005290:Ferric Compounds; D007070:Immunoglobulin A; D005291:Ferrichrome; D004758:Enterobactin; D012694:Serine; C014554:ferrienterochelin; C025314:ferric citrate; D007501:Iron