Fibronectin enhances the phagocytic activity of cultured rabbit keratocytes

To understand corneal stromal wound healing, we investigated the effect of fibronectin (FN) on the phagocytic activity of rabbit corneal keratocytes. The phagocytic activity was measured under a dark-field microscope using polystyrene latex beads coated with either FN, bovine serum albumin, or both. The percentage of phagocytosing cells increased with incubation time. The phagocytic activity was significantly enhanced in a dose-dependent manner by coating beads with FN. Transmission electron microscopic observation demonstrated that latex beads were internalized into the cytoplasm and were surrounded by limiting membranes. These findings indicate that cultured keratocytes have phagocytic activity and that FN shows opsonic effects on the phagocytic activity, suggesting that FN in the injured corneal stroma may play a role in stromal wound repair by opsonic effects.