Clinical Application Of Human Leucocyte Antigen (HLA) Amino Acid Residue Matching In Keratoplasty

BackgroundCorneal disease is one of the main causes of blindness, only secondary to cataract in China. Corneal transplantation is the most effective treatment for corneal blindness. Because immunological rejection could lead to the failure of transplantation, especially in the high-risk cases. Effective prevention of corneal graft rejection is very important for the success of the operation. Recently some researchers considered that the difference of MHC and non-compatibility between the donor and recipient may be the main causes of immunological rejection, and HLA typing in corneal transplantation was reported. Most of these reports, however, were retrospective and of debatable. Zero HLA-A, B, DR Antigen Mismatch (HLA 0 Ag MM) application are not widely used in clinic. The HLA amino acid residue matching (HLA Res M) in kidney transplantation by Terasaki made it possible to apply the principle in keratoplasty. Based on HLA Res M, we chose suitable donor-recipient by HLA-ⅠandⅡtyping before keratoplasty.We expected that low-matching donor-recipient could decrease the difference of HLA subtypes and increase the compatibility between the donor and recipient, which may reduce the rejection rate and keep grafts transparent.Method, results and conclusion1. Experimental studies of HLA antigen expression of the normal corneaObjective: To measure the quantitative expression of HLA-A, B, C and HLA-DR on the corneas from normal human eyes for HLA typing in the donor and recipient. Methods: The corneal epithelial cells (C-Epi) and endothelial cells (C-EC) of 40 normal human eyes were primary cultured in vitro. HLA-A, B, C and HLA-DR were marked by indirect immunofluorecent method and analyzed with ACAS-570. Results: HLA-A, B, C were expressed on both C-Epi (601.0±22.6) and C- EC (511.5±20.5), and the level of antigen expresssion on C-Epi were higher than that on C-EC (P<0.01). However, no detectable HLA-DR was found on both corneal cells. Conclusion: There were expressions of HLA-A, B, C in both human corneal epithelial and endothelial cells in primary culture.2. Initially clinical application of HLA Res M in corneal blindness resulted from eye injuries and infectionObjective:To initially evaluate the role of HLA Res M in the choice of the suitable donor-recipient match befrore surgery, especially in severe eye trauma and infection. Methods: By monoclonial antibody method and Micro-SSP DNA-based method, HLA-A, B and HLA-DR were assayed respectively for the donor and four patients with corneal blindness resulted from severe eye injuries and corneal infection before keratoplasty. According to the HLA Res M, low-mismatching for suitable donor-recipient were chosen. Result: No evidence of rejection was found in these patients. Conclusion: The typing method of HLA-Ⅰand HLA-Ⅱwas convenient, fast and reliable. It is feasible and practicable to choose suitable donor-recipient by HLA Res M before the transplantation.3. Clinical application of HLA Res M in high-risk keratoplastyObjective: To evaluate the importance of HLA Res M in high-risk corneal transplantation. Methods: There were 44 eyes with remarkable neovascularization or whole corneal ulcer with no response to treatment. The cases were divided into 4 groups of 2, 3, 4, 5 HLA mismatching (MM). High-MM group was composed of 4 MM, 5 MM and low-MM group was composed of 2 MM, 3 MM. Results: The rejection rate was 79.5%,including 9.1% in 2 MM, 11.3% in 3 MM, 27.3% in 4 MM, and 31.8% in 5 MM. The rejection rate was much higher in high-MM group of 4 MM and 5 MM (59.1%) than in low-MM group of 2 MM and 3 MM (20.4%), (P=0.044<0.05). Conclusions: The results showed that HLA Res M before corneal transplantation play an important role in keratoplasty. Low-mismatching donor-recipient could reduce rejection rate.4. Clinical application of HLA Res M in corneal blindness resulted from severe eye injuriesObjective: To evaluate respectively the importance of HLA Res M in high-risk and low-risk corenal blindness resulted from eye trauma before keratoplasty. Methods: There were 67 recipient eyes divided into high-risk (51 eyes) and low-risk (16 eyes) groups according to the degree of corneal neovascularization. The cases were subdivided into 2 groups: high-mismatching (MM) group composed of 4 MM, 5 MM and low-MM group composed of 2 MM, 3 MM. Results: The rejection rate in high-risk group (76.5%) was significantly higher than low-risk group (31.3%), (P=0.001). And in high-risk group, the rejection rate (90.5%) in high-MM group was much higher by 1.772 times than that in low-MM group (63.2%) (P=0.00461), RR=1.772. The BCVA in low-MM group was better than high-MM group (P<0.01). However, in low-risk group there was no significant difference of rejection rate between high-MM (33.3%) and low-MM (25.0%), (P=1.00). The BCVA had no significant difference in both group too. Conclusions: The results showed that HLA Res M played an important role in reducing rejection rate, indicating that accurate HLA typing is needed before keratoplasty. If possible, we should choose the better-matched donor-recipient according to HLA Res M, especially in high-risk cornea with severe neovascularization.In short, in this study HLA Res M was applied firstly in keratoplasty brfore transplantation in domestic. Low-mismatching donor-recipient could reduce immunological rejection rate and keep graft transparent in high-risk corneal blindness. The DNA-based typing methods for HLA antigens are practicable and feasible. However, low-mismatching of HLA could not completely stop rejection. Immunosuppressive should be still used after the transplantation.