JBC, Vol. 252, Issue 6, 1865-1868, Mar, 1977
Effects of chemical modification of antibodies on their clearance from the circulation. Addition of simple aliphatic compounds by reductive alkylation and carbodiimide-promoted amide formation
J. L. Winkelhake
Anti-hapten antibodies from the ascitic fluid of inbred mice were purified
by immunoadsorption and characterized immunochemically for in vivo studies
of their plasma clearance rates and organ distributions after chemical
modification. Following sodium borohydride-promoted reductive methylation
and carbodiimide-promoted amide linkage of glycine and several other simple
aliphatic compounds, the antibody populations were recharacterized,
radiolabeled, and introduced intravenously into syngeneic animals. Using
double radioiodine labels, it was possible to show that stoichiometric
combinations of additive and chemical reactant did not alter antibody
survival time in the circulation or antigen-binding capabilities. However,
modifications involving excess reagent (carbodiimide or sodium borohydride)
resulted in significant decreases in both circulatory longevity and ligand
binding capacities. Excess carbodiimide treatments resulted in
immunoglobulin cross-linkage which could be detected by molecular sieve
chromatography. Increased kidney localization found with
carbodiimide-treated antibodies was apparently due to trapping of the
cross-linked aggregates. Elevated clearance of highly methylated antibodies
could not be attributed to a single organ. However, sodium
borohydride-catalyzed reductive methylation resulted in antibody
populations which were localized primarily in the liver and spleen. Results
are evaluated in terms of the concept, developed in this paper, of
essential groups for the circulatory longevity of glycoproteins.