A simplified method for screening siblings for HLA identity using short tandem repeat (STR) polymorphisms

The degree of major histocompatibility complex matching between purebred Maltese and mongrel dogs using microsatellite markers

Long-term maintenance of transplanted organs is one of the major factors that increases survival time of recipients. Although obtaining a major histocompatibility complex (MHC)-matched donor with the recipient is essential for successful organ transplantation, there have been limited reports on MHC matching between dogs. In this study, we analyzed the canine MHC matching rates using Maltese, one of the most popular purebred dogs, and mongrel dogs in Korea. Genomic DNA was extracted from blood leukocytes and DNA was amplified by polymerase chain reaction with primers specific to MHC microsatellite markers. The MHC matching degree was confirmed by the microsatellite markers using polyacrylamide gel electrophoresis. The MHC matching rates of each donor-recipient groups including Maltese-Maltese, mongrel-mongrel and Maltese-mongrel were 4.76%, 5.13% and 6.67%, respectively. There were no significant differences in the MHC matching degree between each group. These results demonstrate that MHC-matched donors could be selected from other breeds as much as from the same breed for transplantation. Knowledge of the MHC matching degree of purebred and mongrel dogs would offer valuable information not only for improving the success rate of organ transplantation surgery in canine patients but also for transplantation research using experimental canine models.

Hidden genomic MHC disparity between HLA-matched sibling pairs in hematopoietic stem cell transplantation

Matching classical HLA alleles between donor and recipient is an important factor in avoiding adverse immunological effects in HSCT. Siblings with no differences in HLA alleles, either due to identical-by-state or identical-by-descent status, are considered to be optimal donors. We carried out a retrospective genomic sequence and SNP analysis of 336 fully HLA-A, -B, -DRB1 matched and 14 partially HLA-matched sibling HSCT pairs to determine the level of undetected mismatching within the MHC segment as well as to map their recombination sites. The genomic sequence of 34 genes locating in the MHC region revealed allelic mismatching at 1 to 8 additional genes in partially HLA-matched pairs. Also, fully matched pairs were found to have mismatching either at HLA-DPB1 or at non-HLA region within the MHC segment. Altogether, 3.9% of fully HLA-matched HSCT pairs had large genomic mismatching in the MHC segment. Recombination sites mapped to certain restricted locations. The number of mismatched nucleotides correlated with the risk of GvHD supporting the central role of full HLA matching in HSCT. High-density genome analysis revealed that fully HLA-matched siblings may not have identical MHC segments and even single allelic mismatching at any classical HLA gene often implies larger genomic differences along MHC.

Standardized genotyping of HLA STR by CE as surrogate for HLA class I and II markers and for identification of HLA identical siblings

Linkage disequilibria (LD) between alleles and haplotypes of human leucocyte antigen, locus A (HLA) and STR loci located in the human major histocompatibility complex were analyzed in order to investigate whether or not HLA alleles and haplotypes are predictable by alleles or haplotypes of HLA STRs. Standardized genotyping of eight STR loci (D6S2972, D6S2906, D6S2691, D6S2678, D6S2792, D6S2789, D6S273, and DQIV) was performed by CE on 600 individuals from 150 Austrian Caucasoid families with known HLA-A,-B,-C and -DRB1 typing. From those, 576 full haplotypes of four HLA and eight STR loci were obtained. Haplotypes of two flanking STRs predicted HLA alleles and two-locus HLA haplotypes better than single STR alleles, except HLA-DRB1 alleles (92% were in LD with DQIV alleles only). A percentage of 65-86% of three and four-locus HLA haplotypes were in LD with haplotypes of three, four, and eight of their flanking STR loci including numerous clear-cut predictions (20-61%). All eight and a set of the four most informative STR loci D6S2972, D6S2678, D6S2792, and DQIV could identify all HLA identical and nonidentical siblings in 138 pairs of siblings. The results of this proof of concept study in Austrian Caucasoids show, that HLA STRs can aid the definition of HLA-A,-B,-C,-DRB1 haplotypes and the selection of sibling donors for stem cell transplantation.

Identifying the degree of major histocompatibility complex matching in genetically unrelated dogs with the use of microsatellite markers

BACKGROUND

The dog has served as an important experimental model for biomedical research such as transplantation and developing immunosuppressive agents. Although major histocompatibility complex (MHC) in dogs is a dominant factor of graft rejection, it has not been well investigated in dogs compared with human. For that reason, imprecise cross-matching or time-consuming sequence-based typing methods have generally been used to choose specific donor and recipient pairs. Investigation of matching distribution of MHC in dogs with the use of simple and accurate methods would be beneficial for biomedical researchers. The aim of this study was to identify the diversity of dog leukocyte antigen (DLA) types in genetically unrelated dogs by means of microsatellite markers.

METHODS

Thirty-three Beagle and Shih-Tzu dogs, which were negative in cross-matching, were chosen. The genomic DNA was isolated from peripheral blood leukocytes, and highly polymorphic short tandem repeats located in MHC class I and II were amplified with the use of specific primers.

RESULTS

Among all of the dogs, MHC matching groups, including class I full match-class II full match (M-M), class I full match-class II haplo match (M-H), class I haplo match-class II full match (H-M), class I haplo match-class II haplo match (H-H) groups, were ∼1.55%, 0.39%, 1.94%, and 6.59%, respectively. MHC class I nonmatch-class II nonmatch (U-U) groups were 58.14% of the total dogs.

CONCLUSIONS

Because differences of histocompatibility between donor and recipient leads to various allograft rejections, knowledge of the distribution of MHC matching in unrelated dogs would be helpful in designing studies and to get more accurate results from experiments using dog transplantation models.

Sequence-based definition of eight short tandem repeat loci located within the HLA-region in an Austrian population

Sequenced allelic ladders are a prerequisite for reliable genotyping of short tandem repeat (STR) polymorphisms and consistent results across instrument platforms. For eight STR-loci located on the short arm of chromosome 6 (6p21.3), a sequenced based nomenclature was established according to international recommendations. Publicly available reference DNA samples were sequenced enabling interested laboratories to construct their own allelic ladders. Three tetrameric (D6S2691, D6S2678, DQIV), one trimeric (D6S2906) and four dimeric repeat loci (D6S2972, D6S2792, D6S2789, D6S273) were investigated. Apart from the very complex sequence structure at the DQIV locus, three loci showed a compound and four loci a simple repeat pattern. In the flanking regions of some loci additional single nucleotide and insertion/deletion polymorphisms occurred as well as sequence polymorphisms within the repeat region of alleles with the same length. In an Austrian Caucasoid population sample (n=293) between eight and 22 alleles were found. No significant deviation from Hardy-Weinberg expectations was observed, the power of discrimination ranged from 0.826 to 0.978. The loci cover the HLA-coding region from HLA-A to HLA-DQB1 and can be used for a better definition of HLA haplotypes for population and disease association studies, recombination point mapping, haematopoietic stem cell transplantation as well as for identity and relationship testing.

A glow of HLA typing in organ transplantation

The transplant of organs and tissues is one of the greatest curative achievements of this century. In organ transplantation, the adaptive immunity is considered the main response exerted to the transplanted tissue, since the main goal of the immune response is the MHC (major histocompatibility complex) molecules expressed on the surface of donor cells. Cell surface molecules that induce an antigenic stimulus cause the rejection immune response to grafted tissue or organ. A wide variety of transplantation antigens have been described, including the major histocompatibility molecules, minor histocompatibility antigens, ABO blood group antigens and endothelial cell antigens. The sensitization to MHC antigens may be caused by transfusions, pregnancy, or failed previous grafts leading to development of anti-human leukocyte antigen (HLA) antibodies that are important factor responsible for graft rejection in solid organ transplantation and play a role in post-transfusion complication Anti-HLA Abs may be present in healthy individuals. Methods for HLA typing are described, including serological methods, molecular techniques of sequence-specific priming (SSP), sequence-specific oligonucleotide probing (SSOP), Sequence based typing (SBT) and reference strand-based conformation analysis (RSCA) method. Problems with organ transplantation are reservoir of organs and immune suppressive treatments that used to decrease rate of rejection with less side effect and complications.