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An international collaborative study of 45 transplant centers was undertaken at the 14th International HLA (human leukocyte antigen) and Immunogenetics Workshop to see if HLA antibodies detected posttransplant are predictive of chronic graft failure. With the newly developed assay, MICA (major histocompatibility complex class I-related chain A) antibodies were also measured and their effect analyzed. Total of 5219 sera from patients who were more than 6 months posttransplant with functioning graft were tested for HLA antibodies by enzyme-linked immunosorbent assay, flow cytometry, or Luminex. HLA antibodies were found in 27.2% of kidney patients, 23.6% in the liver, 52.7% in the heart, and 21.7% in the lung. The method of antibody testing did not have a marked influence on the frequency of antibodies detected. MICA antibodies were detected in 15% of kidney patients, 30% of heart patients, and 31% of liver patients. Among 948 kidney patients who had HLA antibodies, 7.3% had rejected their graft within 1 year of testing, compared with 1.7% in 2615 patients without HLA antibodies (P= 0.8 x 10(-17)). Death occurred in 1.4% of total kidney patients and did not correlate to the presence of antibodies. We conclude that patients with posttransplant HLA antibodies indeed have a higher rate of chronic graft failure and that posttransplant antibodies are predictive of chronic rejection.

The aim of this study was to determine whether a common diabetic haplotype, including human leukocyte antigen (HLA)-B8 and HLA-DR3, in Northern India is the same haplotype as the European HLA-B8-DR3 haplotype. DNA samples from Northern Indian subjects selected on the basis of HLA-B8 and HLA-DR3 were tested for microsatellite and single nucleotide polymorphism alleles throughout the major histocompatibility complex (MHC). It was found that the Indian samples represent a conserved haplotype in which all alleles were shared by Indian subjects with HLA-B8 and HLA-DR3, but were different to those that are characteristic of the European 8.1 ancestral haplotype. The Indian and European haplotypes share HLA-B*0801, HLA-DRB1*0301 and HLA-DQB1*02 but differ for subtypes of HLA-Cw*07 and HLA-DRB3 and all central MHC alleles tested. In contrast, Indian subjects selected on the basis of HLA-B58 ( 1-17) and HLA-DR3 shared the same alleles at other MHC loci as have been described in the common Chinese haplotype with HLA-B58/17 and HLA-DR3. A third haplotype, HLA-B50/21 and HLA-DR3, was also found to be highly conserved but shares little in common with the other two HLA-DR3-containing Indian haplotypes.

The HLA-DRB1 sequencing based typing strategies reported to date require separate amplifications of each sample with a series of group-specific primers followed by sequencing of any resulting polymerase chain reaction (PCR) products. Whilst this results in high resolution typing in the majority of cases, a number of unnecessary amplifications are performed. We report here a novel approach where amplification of the second exon of HLA-DRB1 is performed in a single tube for all alleles. Retrospective analysis of 642 consecutive Western Australian unrelated bone marrow registry donors has shown that this approach results in unambiguous typings in 71.1% of cases. Ambiguities can be readily resolved if necessary with a single additional sequencing reaction on the original PCR product.

The World Marrow Donor Association has formulated guidelines for establishing the extent and quality of histocompatibility testing for unrelated donor registries, umbilical cord blood banks, and transplant centers involved in international exchange of hematopoietic stem cells for allogeneic transplantation. Registry and cord blood bank guidelines suggest that, at a minimum, initial HLA typing should be performed for three HLA loci, HLA-A, -B, and -DR, at low resolution/split antigen level. DNA-based testing methods should be utilized for HLA-DR typing. DNA-based testing for HLA-A and -B should replace serologic testing of new volunteer donors and cord blood units as robust protocols and reagents become available to the laboratories. Transplant center guidelines for typing of patient, family and to confirm the HLA types of potential unrelated donors should include, at the minimum, typing HLA-A, B, and -DR loci using primarily DNA-based testing methods at allele level resolution for DRB1 and low resolution/ split antigen level for HLA-A and -B. It is strongly recommended that the typing of a patient and the selected donor be performed using the same set of reagents, methodology, and interpretation criteria with fresh tissue samples to ensure HLA identity. Guidelines for laboratory accreditation, approaches to quality assurance and quality control for HLA testing, and suggestions for the format of the HLA database of donor types are also outlined.