Abstract

Colchicine-specific goat IgG and Fab fragments were cationized by covalent coupling of hexamethylenediamine. The immunoreactivity of antibodies was not changed following cationization. The interaction of¹²⁵I-radiolabeled native (nIgG and nFab) and cationized immunoglobulin G (cIgG) and Fab fragments (cFab) with liver was investigated using isolated perfused rat liver (IPRL) and isolated rat hepatic parenchymal cells (PCs) and nonparenchymal cells (NPCs) in suspension. ¹²⁵I-cIgG or¹²⁵I-cFab were more rapidly cleared from the perfusate than the corresponding native proteins. Both cIgG and cFab declined biexponentially over time in the perfusate. In contrast, the native IgG and Fab decreased monoexponentially. The half-lives of the initial and terminal phases were 5.2 ± 1.6 min and 355.1 ± 17.2 min for cIgG and 14.7 ± 3.4 min and 552.4 ± 23.7 min for cFab. The terminal half-lives of nIgG (467.4 ± 11.6 min) and nFab (880.1 ± 39.6 min) were longer than those of cationized molecules. The biliary protein extraction ratio of cationized IgG and Fab was greater than that of native IgG and Fab: 0.13% (cIgG), 0.02% (nIgG), 0.23% (cFab), and 0.17% (nFab). The uptake of cIgG and cFab by both PCs and NPCs was dose-dependent and was about 6-fold and 8-fold higher than that of their native counterparts, respectively. Throughout the experiment, liver viability was determined, and no toxicity was observed according to physiological analysis (bile flow rate, portal vein pressure, and pH) and biochemical analysis (glucose and hepatic enzymes: alanine transaminase, aspartate transaminase, lactate dehydrogenase) in perfusate.