HLA Matching in High Risk Corneal Grafting

Abstract

Purpose: : To establish if HLA-A, B and DR tissue matching in high risk corneal graft is associated with a reduced risk of graft rejection and associated graft failure.

Methods: : Forty consecutive patients who underwent HLA matched penetrating keratoplasty were included in the study. The 40 eyes were considered to be at a high risk of immune mediated graft rejection and failure due to previous failed grafts, corneal stromal vascularisation in more than 2 quadrants, previous history of chemical injury and herpes simplex keratitis infection leading to corneal scarring and vascularisation.The following data was collected retrospectively - indication for performing the HLA matched graft, number of rejection episodes and time to the 1st rejection episode, status of the graft at final follow up (clear or failed/edematous), systemic immunosuppression, visual acuity at final follow up and HLA mismatches at A, B and DR loci.

Results: : Thirty three grafts out of 40 (82.5%) remained clear at final follow up which ranged from 10-108 months. Seven grafts were deemed to have failed.The failed grafts had a total of 2 to 4 mismatches at the HLA- A, B and DR loci (3 had 2 mismatches, 3 had 3 and 1 had 4). In the 33 grafts that remained clear mismatches ranged from 1 to 4 (3 grafts had 1, 6 grafts had 2, 15 had 3 and 9 had 4 mismatches).On assessing the mismatches at the HLA-A and B loci, 1 failed graft had 1 mismatch and 5 had 2, whereas in the 33 clear grafts this ranged from 0 to 3 (2 grafts had 0, 4 had 1, 26 had 2 and 1 had 3 mismatches).At the DR loci, the mismatches in the failed grafts ranged from 0 to 2 (2 had 0 mismatches, 4 had 1 and 1 had 2 mismatches). In the successful grafts the mismatches at this loci ranged from 0 to 2 (5 grafts had 0 mismatches, 17 had 1, 11 had 2 mismatches).Thirty six patients had been on systemic suppression for at least 12 months. Six of these had a failed graft at final follow up. Of the 4 patients who did not receive systemic suppression, 1 had a failed graft.

Conclusions: : HLA-A, B and DR matching appears to reduce the risk of graft rejection and failure in high risk grafts. However no conclusions can be drawn regarding the superiority of A and B loci matching over DR matching in reducing the risk of graft rejection and failure.

Keywords: cornea: clinical science • transplantation • genetics