Transport of immunoglobulin G by endothelial vesicles in isolated capillaries.

The ability of capillary endothelial vesicles to transport immunoglobulin G (IgG) across the capillary wall was investigated. Isolated capillary endothelial cells were found to endocytose fluorescent-labeled IgG via a bulk fluid-phase mechanism. When placed in marker-free medium the cells released all previously ingested label. Cationization of IgG causes greater amounts of the protein to be ingested as compared to normal IgG. Cationized IgG is probably endocytosed via an adsorptive mechanism, allowing greater efficiency in its uptake. It is concluded that IgG can be transcytosed by isolated endothelial cells of capillary origin and that the charge of the IgG molecule is important in determining its mode of uptake.