title: Antibodies to lactalbumin interfere with its radioimmunoassay in human plasma.
abstract: Two radioimmunoassays for human lactalbumin have been established using a rabbit antiserum. One assay uses a second antibody to separate bound from free label; the other uses polyethylene glycol to precipitate gamma globulin non-specifically. We have confirmed that about half the normal human population have a substance in their blood which inhibits the binding of lactalbumin to the rabbit antibody. Comparison of the two assays has demonstrated that this material is not lactalbumin but a naturally occurring antibody. We have shown that it is in the IgG fraction of human plasma and is probably a cross-reacting antibody to bovine lactalbumin. None out of fifteen males and fourteen out of fifty eight non-pregnant, non-lactating females had low levels of lactalbumin in the their blood (0.6--2.0 ng/ml). Our assay could not detect a statistically significant difference between normal women and those with either benign breast disease or metastatic mammary carcinoma.
mesh_terms: D000818:Animals; D000906:Antibodies / Q000032:analysis; D002417:Cattle / Q000276:immunology; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D003429:Cross Reactions; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D007768:Lactalbumin / Q000097:blood* / Q000276:immunology; D008297:Male; D011092:Polyethylene Glycols; D011247:Pregnancy; D011817:Rabbits / Q000276:immunology; D011863:Radioimmunoassay / Q000379:methods
chemical_list: D000906:Antibodies; D007074:Immunoglobulin G; D011092:Polyethylene Glycols; D007768:Lactalbumin