HLA-C AND HLA-P ANTIBODY IN RENAL TRANSPLANTED PATIENTS IN HONG KONG Alan Li, Karen Kwong, Jenny Ho, Janette Kwok. Queen Mary Hospital, Hong Kong, Hong Kong. Aims: (1) To analyze the incidence of HLA-C and -DP antibodies in both antibody-mediated rejection (AMR) and non-AMR renal patients before and after transplantation; (2) To investigate the correlation between donor-specific antibodies (DSA) and AMR in both HLA-C and -DP loci. Methods: From September 2012 to June 2015, 269 post-transplant serum samples were tested for HLA class I antibodies while 285 post-transplant serum samples were tested for HLA class II antibodies using LIFECODES Single Antigen assay. 34 and 46 patients positive for HLA-C and -DP antibodies respectively were selected and pre-transplant sera were screened for any pre-existing antibodies. The corresponding donors for the patients with HLA-C or HLA-DP antibodies were investigated further to determine if the antibodies were donor-specific. 23 and 21 donors were typed for HLA-C and HLA-DP respectively by Polymerase Chain Reaction-Sequence-Specific Oligonucleotide assay. Results: HLA-C antibodies were detected at a higher frequency in AMR group (21.3%) than in non-AMR group (10.8%) while HLA-DP antibodies were detected at a slightly higher frequency in AMR group (22.4%) than in non-AMR group (14.5%). The overall frequencies of detecting HLA-C antibodies and -DP antibodies in post-transplant renal patients were 12.6% and 16.1% respectively. The results showed that the presence of HLA-C antibodies was associated with the occurrence of AMR (p < 0.05), but not in HLA-DP antibodies (p > 0.05). Over 80% patients, HLA-C (82.4%) and -DP antibodies (80.4%) were de novo after transplantation. The percentage of detecting HLA-C DSA in AMR patients (57.1%) was significantly higher than that in nonAMR patients (12.5%). In contrast, the percentage of detecting HLA-DP DSA in patients with AMR (25%) was lower than that found in non-AMR patients (30.8%). The findings showed that the occurrence of AMR was associated with the presence of HLA-C DSA (p < 0.05), but HLA-DP DSA did not appear to be directly associated with AMR. (p > 0.05). Conclusions: HLA-C and -DP antibodies were detected at a higher frequency in AMR group, but the difference was only statistically significant for HLA-C antibodies. HLA-C DSA were associated with AMR, but such association was not observed in HLA-DP DSA.
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FOUR UNRELATED INDIVIDUALS SHARING A HAPLOTYPE WITH A REAR ALLELE DQB1⁄06:123 Amal Al Gharably, Fadi Al Zayer, sahar Sandooqah, Maha Al-Harbi, Moheeb Al-Awwami. King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia. In 2013, one laboratory from Saudi Arabia reported a rare allele of DQB1 locus to IMGT using two different cells. At our laboratory, we observed four unrelated individuals typed for DQB1 locus by RSSO as DQB1⁄06:29/123. Since DQB1⁄06:29/123 has the same beads reaction by RSSO, Sequence based typing for the four individuals confirmed the typing to be DQB1⁄06:123. In addition, the four unrelated individuals shared the same haplotype (A⁄02; B⁄50; C⁄06; DRB1⁄15:01; DQB1⁄06:123). This particular allele may be included in the common and well-documented (CWD) alleles. As per the 2012 published CWD HLA alleles an allele that is detected three times or more in unrelated individuals with a specific haplotype as discussed above should be included in the well-documented category.