[The study of FK506 eye drops preventing and treating immune rejection on limbal allograft transplantation].

OBJECTIVE

To evaluate the general cause of limbal allograft transplantation rejection and the effects of the immunosuppressant FK506.

METHODS

Limbal deficiency models were established in 48 New Zealand rabbits, which were randomized into three groups of 16 rabbits each. Limbal allograft transplantation was performed one month later. After transplantation, the FK506 group, the CsA group and the untreated group were treated with FK506 eye drops (0.5 g/L), 1% CsA eye drops and physiological saline, respectively. Graft survival and ocular surface were observed clinically for 10 weeks. Impression cytology was performed on the central cornea of the rabbit one month after limbal ablation, 1 day before allograft transplantation, and two and four weeks after transplantation. The expression of CD25 in peripheral T cells was identified dynamically one day before and one and eight weeks after transplantation. The expression of CD25 on the limbal allograft and lymphocyte infiltration was also identified dynamically the fourth, eighth and tenth week after transplantation.

RESULTS

Conjunctivalization of corneal epithelium was found in the limbal deficiency model by impression cytology. Two weeks after limbal allograft transplantation, the central corneal epithelium regained corneal phenotype. Four weeks later, the ocular surface of FK506 group and CsA group continued to express corneal phenotype. Epithelium rejection appeared first in the untreated group (P < 0.05), which had the highest level of the lymphocyte infiltration and the expression of CD25 in peripheral blood and allografts after limbal allograft transplantation (P < 0.05). Epithelium rejection occurred next with the CsA group. FK506 group epithelium rejection occurred last and had the lowest level of the lymphocyte infiltration and the expression of CD25 in peripheral T cell and limbal allografts.

CONCLUSIONS

Topically administered FK506 eye drops early after limbal allograft transplantation can delay allograft rejection by effectively inhibiting the expression of CD25 in peripheral T cells and limbal allografts. Also, FK506 is more effective than CsA.