Abstract
Rabbit anti-hapten antibodies were purified by affinity chromatography and characterized immunochemical for in vivo studies of their blood clearance rate and organ distribution after treatment with various glycosidases. Following sequential removal of sialic acid, galactose, and N-acetylglucosamine with the appropriate cellulose-immobilized exoglycosidases, the antibody populations were recharacterized, radiolabeled, and introduced intravenously into the original animals. Using double radioiodine lables it was possible to demonstrate alterations in purified antibody survival times in the circulation and altered organ distribution after glycolytic cleavage. Removal of terminal sialic acid resulted in rapid blood clearance and enhanced localization of asialoantibody in the liver. Subsequent removal of penultimate galactose residues returned both antibody survival time in the circulation and organ distribution to near normal. Removal of subpenultimate N-acetylglucosamine moieties resulted in aglycosylantibody survival values which were intermediate between asialo- and asialoagalactoantibodies. Removal of the three saccharide also increased kidney localization. The results are evaluated based on current concepts of the biological roles of protein-linked carbohydrate and plasma glycoprotein survival time in the circulation.
Highlights
From the Department of Cancer Biology, The Salk Institute for Biological 92112 and the Department of Developmental and Cell Biology, University 92664
Rabbit anti-hapten antibodies were purified by affinity chromatography and characterized immunochemically for in uiuo studies of their blood clearance rate and organ distribution after treatment with various glycosidases
Removal of terminal sialic acid resulted in rapid blood clearance and enhanced localization of asialoantibody in the liver
Summary
The concept that the terminal sialic acid moiety is crucial to the continued circulation of many, if not most, core-type and mucin-type [1] glycoproteins has been developed by Ashwell and Morel1 [2,3,4]. This hypothesis is based on the fact that neuraminidase treatment of ceruloplasmin [5], orosomucoid, fetuin, haptoglobin, cu,-macroglobulin, chorionic gonadotropin, follicle-stimulating hormone [6], and plasminogen [7] has resulted in rapid clearance of these asialoglycoproteins from the blood when compared with untreated controls.
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