Enhanced cellular uptake and transport of polyclonal immunoglobulin G and Fab after their cationization

Antibodies are poorly transported across cell membranes and biological barr iers in vivo. Cationization of antibody molecules by the derivatization of surface carboxyl groups generating primary amino groups could represent a s trategy for intracellular antibody delivery. Before cationization of polycl onal colchicine-specific IgG and Fab, using hexamethylenediamine the isoele ctric point (pI) of native IgG and Fab (nIgG and nFab) was in the range of 5.9-9.0 and 8.7-9.3, respectively, The pi of cationized IgG and Fab (cIgG a nd cFab) were both higher at 8.7-10.3 and 9.5-11, respectively. The affinit y and specificity of both IgG and Fab were not modified by cationization, W hen HL 60 cells were incubated with the native or cationized I-125-BSA, -Ig G and -Fab, the maximal cellular uptake of cIgG and cFab was 3.2 and 2.4 ti mes higher than that of nIgG and nFab at an extracellular concentration of 500 ng/ml, Results also indicated that the uptake was dose- and temperature -dependent suggesting absorptive-mediated endocytosis of cationized antibod ies by HL 60 cells, Confocal microscopy analysis indicated that the cationi zed antibodies were present in the plasma membranes and cytoplasm of HL 60 cells, Finally, a study with bovine arterial endothelial monolayer cells sh owed that the transport of cIgG and cFab through the monolayer cells was 3. 3- and 4.3-fold higher for I-125-cIgG and I-125-cFab than those of the corr esponding native forms.