Effect of leukocytes on corneal cellular proliferation and wound healing.

PURPOSE To establish whether fucoidin, by blocking the adhesion of leukocytes on the limbal vascular endothelium, prevents extravasation of the cells from the blood stream into the limbal stroma and the wounded area after corneal injury. Successful leukocyte blocking enabled investigation of the influence of leukocytes on corneal cellular proliferation after corneal wounding. METHODS Thirty-two New Zealand White rabbits were used. Photorefractive keratectomy (PRK) and a standardized alkali corneal wound were used as models in two sets of experiments. In half of the injured rabbits fucoidin was used to prevent leukocytes from leaving the local vessels. The efficiency of the blocking technique was evaluated by counting the number of leukocytes in the limbal and wounded corneal areas. Proliferating cell nuclear antigen (PCNA) was used as a marker for proliferative activity. RESULTS The infiltration of leukocytes into the limbus and the cornea after PRK and alkali injuries can be blocked by fucoidin. The healing rate of corneal epithelium after alkali burn was retarded in the absence of leukocytes. PCNA expression was enhanced in the presence of leukocytes. Fucoidin per se had no influence on corneal cell proliferation and wound healing. CONCLUSIONS Polymorphonuclear leukocytes (PMNs) can be prevented from entering the cornea in vivo by fucoidin after PRK and after alkali burn. The corneal epithelial healing rate is delayed in the absence of PMNs in vivo, and PCNA expression increases in the presence of leukocytes.