Effect of HLA-A and -DPB1 Matching in Corneal Transplantation N. Morita, B. Munkhbat, B. Gansuvd, N. Kanai, M. Hagihara, J. Shimazaki, K. Tsubota, and K. Tsuji T HE CORNEA has been regarded as an immunologi- cally privileged site, because of the absence of blood vessels and lymphatics. However, as is the case with other tissues, immune rejection represents the main cause of graft failure in corneal transplantation. Although possible bene- fits of HLA matching on corneal graft outcome have been studied for many years, conflicting results have been ob- tained. 1–5 This is the first study for the effect of HLA class I and class II allele matching in corneal transplantation using DNA typing methods. MATERIALS AND METHODS Study Subjects A total of 81 transplant patients who had received corneal allo- grafts and had been followed at the Department of Ophthalmology, Tokyo Dental College, were studied. All donor corneas were obtained from eye banks in the United States, and confirmed to be suitable for transplantation, and grafted without previous HLA typing. Transplant recipients were subdivided into two groups, 51 high- risk and 30 low-risk cases (Table 1). The high-risk group was defined as having stromal vascularization in more than two quad- rants of the cornea or a history of previous corneal graft failure. There was no significant difference between the two groups in the rejection episodes. The median follow-up period was 32 months. Tissue Samples for DNA Typing All donor corneas were preserved at 4°C in a preservation medium (Optisol; Chiron Ophthalmics, Irvine, Calif), until transplantation. The parts of the donor ocular tissue that were not used for transplantation, and the recipient’s cornea removed at the time of surgery, were stored at -80°C and then subjected to DNA extrac- tion and subsequent HLA class II and class I DNA typing. Genomic DNA Extraction The extraction of genomic DNA was performed by the phenol/ chloroform method, according to the 11th International Histocom- patibility Workshop protocol. DNA Typing for HLA Class I and II Alleles HLA class I DNA typing for HLA-A and -B alleles was performed by the PCR-SSOP (polymerase chain reaction-sequence specific oligonucleotide probes) method, as described previously. 6,7 HLA class II DNA typing for HLA-DRB1, -DQB1, and -DPB1 alleles was performed by the PCR-RFLP (polymerase chain reaction- restriction fragment length polymorphism) method using an SMI TEST typing kit (Sumitomo Metal Industries, Ltd, Japan). Statistical Analysis The significance of differences among groups was calculated by the chi-square test, with Yate’s correction using raw data from HLA class I and II DNA typing. RESULTS The 81 transplant recipients were initially typed for HLA class II (DRB1, DQB1, and DPB1), then 80 for HLA-A, and 79 for HLA-B. The difference in these numbers among them is due to a shortage of donor DNA samples (Table 2). For statistical analysis, transplant recipients were subdi- vided into groups with matching (one to two alleles matched) and without matching (no allele matched) for each locus. As shown in Table 2, rejection episodes in the high-risk group were significantly less frequent in transplant recipi- ents with HLA-A matching than in those without HLA-A matching. Only 2 of 16 transplant recipients with HLA-A matching experienced a rejection episode, in contrast to 16 of 34 without HLA-A matching (P  .039). Furthermore, HLA-A matching was found to have a significant benefit in the total of 80 transplant recipients, ie, when the high and low-risk groups were analyzed together (P = .025). Among HLA class II alleles, matching for HLA-DPB1 also had a significant benefit in high-risk corneal transplantation. Only 1 of 14 transplant recipients with HLA-DPB1 matching experienced a rejection episode as compared to 17 of 37 without HLA-DPB1 matching (P  .024). No significant differences were observed for HLA-B, -DRB1, and -DQB1 matching (P  .05). From the Department of Transplantation Immunology, Tokai University, School of Medicine, Kanagawa, Japan and the De- partment of Ophthalmology, Tokyo Dental College, Tokyo, Japan. Address reprint requests to N. Morita, Department of Trans- plantation Immunology, Tokai University, School of Medicine, Boseidai, Isehara, Kanagawa, 259-11, Japan. Table 1. Rejection Episodes in Study Groups Observed Study Group Rejection Episode No Rejection Episode Total High-risk group 18 33 51 Low-risk group 6 24 30 Total 24 57 81 © 1998 by Elsevier Science Inc. 0041-1345/98/$19.00 655 Avenue of the Americas, New York, NY 10010 PII S0041-1345(98)01109-9 Transplantation Proceedings, 30, 3491–3492 (1998) 3491