Biodistribution study of a monoclonal antibody specific to link proteins from human cartilage.

We report the use of monoclonal antibody 6F3 prepared against link proteins from human articular cartilage to elucidate the distribution of these glycoproteins within connective and other tissues. By immunohistochemical analysis, we showed that only the Fab fragment could reach the antigenic site in human articular sections. Cross-reactivity of the antibody 6F3 with link proteins purified from rat articular cartilage allowed us to carry out a biodistribution analysis in vivo in the rat. The time course of whole blood and plasma showed maximal activity 6 h after the 20 micrograms i.v. injection of [125I]Fab-6F3. Urinary excretion seems to be a high route of elimination. Moreover, we noticed no radioactive uptake across the blood-brain barrier. A significant fixation of labeled antibody Fab-6F3 was observed in noncartilaginous connective tissues such as aorta, skin and lung. As expected, specific and increased radioactivity was observed in all cartilage tissues, this increase was significantly higher 6 h after the [125I]Fab-6F3 injection than in the other connective tissues.