Progress report on the ASHI/CAP Proficiency Survey Program in Histocompatibility Testing. II. HLA-DR, DQ serologic typing, antibody identification, and B-cell crossmatching. American Society for Histocompatibility of Immunogenetics. College of American Pathologists

Seeking Standardized Definitions for HLA-incompatible Kidney Transplants: A Systematic Review

BACKGROUND

There is no standard definition for "HLA incompatible" transplants. For the first time, we systematically assessed how HLA incompatibility was defined in contemporary peer-reviewed publications and its prognostic implication to transplant outcomes.

METHODS

We combined 2 independent searches of MEDLINE, EMBASE, and the Cochrane Library from 2015 to 2019. Content-expert reviewers screened for original research on outcomes of HLA-incompatible transplants (defined as allele or molecular mismatch and solid-phase or cell-based assays). We ascertained the completeness of reporting on a predefined set of variables assessing HLA incompatibility, therapies, and outcomes. Given significant heterogeneity, we conducted narrative synthesis and assessed risk of bias in studies examining the association between death-censored graft failure and HLA incompatibility.

RESULTS

Of 6656 screened articles, 163 evaluated transplant outcomes by HLA incompatibility. Most articles reported on cytotoxic/flow T-cell crossmatches (n = 98). Molecular genotypes were reported for selected loci at the allele-group level. Sixteen articles reported on epitope compatibility. Pretransplant donor-specific HLA antibodies were often considered (n = 143); yet there was heterogeneity in sample handling, assay procedure, and incomplete reporting on donor-specific HLA antibodies assignment. Induction (n = 129) and maintenance immunosuppression (n = 140) were frequently mentioned but less so rejection treatment (n = 72) and desensitization (n = 70). Studies assessing death-censored graft failure risk by HLA incompatibility were vulnerable to bias in the participant, predictor, and analysis domains.

CONCLUSIONS

Optimization of transplant outcomes and personalized care depends on accurate HLA compatibility assessment. Reporting on a standard set of variables will help assess generalizability of research, allow knowledge synthesis, and facilitate international collaboration in clinical trials.

Multilaboratory evaluation of serum analysis for HLA antibody and crossmatch reactivity by lymphocytotoxicity methods

CONTEXT

This report presents results of the serum antibody analysis and crossmatch challenges in the proficiency testing program for histocompatibility testing jointly sponsored by the American Society for Histocompatibility and Immunogenetics and the College of American Pathologists.

OBJECTIVE

To obtain information about consensus rates among participating laboratories that reported antibody screening and crossmatch results by direct complement-dependent lymphocytotoxicity (CDC) and/or anti-human globulin (AHG)-augmentation methods.

DESIGN

We analyzed responses from approximately 165 laboratories participating in 32 surveys during 1993-2000. Most of the testing was done by CDC methods, but increasing proportions of laboratories are using AHG augmentation of these techniques; almost one half of the serum screenings and crossmatches were done by AHG.

RESULTS

A total of 40 serum specimens were screened to determine the percent panel-reactive antibody (PRA) and identify HLA-specific antibodies. Participants often reported very wide ranges of PRA values. Panel-reactive antibody ranges exceeded 60 percentage points for 16 (40%) of the serum screening results by CDC and for 31 (77%) of the results by AHG. The interlaboratory variability of PRA values suggests that in many laboratories, the CDC or AHG procedures were often too insensitive or overly sensitive. The antibody identification results revealed inconsistent patterns among the participants performing CDC or AHG screening. Most participants reported the same primary antibody specificities by both methods. The consensus levels were generally high for the monospecific sera. On the other hand, there was much less agreement among the participants if the sera reacted with 2 or more HLA antigens. Participants using the more sensitive AHG method reported additional antibody specificities in many specimens, but invariably the consensus levels were rather low. A total of 192 serum-cell combinations were used for the crossmatch challenges. There was considerable interlaboratory variability; 21% of the CDC crossmatches and 36% of AHG crossmatches failed to reach the 90% consensus threshold.

CONCLUSIONS

This experience demonstrates considerable inconsistencies in serum screening and crossmatching among laboratories participating in the American Society for Histocompatibility and Immunogenetics/College of American Pathologists surveys. A lack of uniformity in test results may limit the efficient application of these methods in a clinical setting. Standardization of crossmatch and antibody screening techniques is highly desirable.

A special report: histocompatibility testing guidelines for hematopoietic stem cell transplantation using volunteer donors. Quality Assurance and Donor Registries Working Groups of the World Marrow Donor Association

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.

Large-scale DRB and DQB1 oligonucleotide typing for the NMDP registry: progress report from year 2

DNA typing of HLA class II alleles of the DRB1/3/4/5 and DQB1 loci using sequence-specific oligonucleotide probes and polymerase chain reaction amplified DNA has been used for the large-scale typing of donors for the National Marrow Donor Program unrelated donor registry. The results of quality control analysis for the second year of the project (10/1/939/30/94) show the typing continues to be highly accurate, specific, and reliable. The average percent of correctly classified HLA oligotypes (groups of alleles defined by a hybridization pattern with a panel of sequence-specific oligonucleotide probes) based on 9,244 DRB1 and 7,244 DQB1 assignments was 99.8% (range 99.4%100.0%) for DRB1/DRB3/DRB4/DRB5 and 99.8% (range 99.6%100.0%) for DQB1. This level of accuracy is particularly remarkable because the 4,636 DRB quality control samples were tested blindly and could not be distinguished from 57,580 donor samples tested at the same time by the laboratories.

Progress report on the ASHI/CAP Proficiency Survey Program in Histocompatibility Testing. I. HLA-A,B,C typing, antibody screening, and lymphocytotoxicity crossmatching. American Society for Histocompatibility and Immunogenetics. College of American Pathologists

The Histocompatibility Survey Program was organized in 1982 as a joint project by the ASHI and CAP to evaluate laboratory performance in HLA typing, lymphocytotoxicity crossmatching, and antibody analysis. This report summarizes the experience with the HS surveys on HLA class I serology. During a 12-year period, the number of participating laboratories increased from 150 to 285 and HLA typing was done with 90 survey specimens representing 20 HLA-A and 35 HLA-B antigens. Most unsplit antigens were correctly identified in more than 90% of the laboratories. For many antigens, a high percentage of participants reported a split and there was generally a high consensus of a correct assignment. Nevertheless, several antigens were difficult to define, as shown by low consensus rates. During recent years, the assignments of Bw4/6 and HLA-C antigens have significantly improved. Lymphocytotoxicity crossmatching was analyzed for 138 cell-serum combinations tested by an average of 143 laboratories. Comparisons between four techniques (basic NIH, Amos modified, LI, and AHG) showed consistent results (greater than 90% crossmatch compatibility or incompatibility) for 71% of the cell-serum combinations. The crossmatch results with the remaining combinations were more variable for one or more of the crossmatch techniques. Serum antibody identification showed a continued improvement during recent years, and the average consensus for assigning acceptable antibody specificity reached 88%. A performance grading system based on a 90% consensus rate among participants is used to satisfy requirements for laboratory accreditation.