Cross-matching of allogeneic mesenchymal stromal cells eliminates recipient immune targeting.

Allogeneic mesenchymal stromal cells (MSCs) have been used clinically for decades, without cross-matching, on the assumption that they are immune-privileged. In the equine model, we demonstrate innate and adaptive immune responses after repeated intra-articular injection with major histocompatibility complex (MHC) mismatched allogeneic MSCs, but not MHC matched allogeneic or autologous MSCs. We document increased peri-articular edema and synovial effusion, increased synovial cytokine and chemokine concentrations, and development of donor-specific antibodies in mismatched recipients compared with recipients receiving matched allogeneic or autologous MSCs. Importantly, in matched allogeneic and autologous recipients, but not mismatched allogeneic recipients, there was increased stromal derived factor-1 along with increased MSC concentrations in synovial fluid. Until immune recognition of MSCs can be avoided, repeated clinical use of MSCs should be limited to autologous or cross-matched allogeneic MSCs. When non-cross-matched allogeneic MSCs are used in single MSC dose applications, presensitization against donor MHC should be assessed.

The utility of DLA typing for transplantation medicine in canine models.

Transplantation medicine is used for the treatment of severe canine diseases, and the dog leukocyte antigen (DLA) is considered to be important in graft rejection. However, the utility of direct sequencing of both DLA classes I and II has not been assessed thoroughly. Eight healthy beagles with identified DLA genes were divided into two sets of four dogs, each including one donor and three recipients for skin transplantation. The following recipients were selected: one dog with a complete match, one with a haploidentical match, and one with a complete mismatch of the DLA gene with the donor. Full-thickness skin segments were obtained from each donor and transplanted to the recipients. A mixed lymphocyte reaction (MLR) assay was performed and analyzed by flow cytometry. Skin grafts of DLA haploidentical and mismatched pairs were grossly rejected within 14 days, whereas in fully matched DLA pairs, survival was as long as 21 days. Histopathological evaluation also showed moderate to severe lymphocytic infiltration and necrosis in DLA mismatched pairs. As seen in the MLR assay, the stimulation index of DLA mismatched pairs was significantly higher than that of fully matched DLA pairs in both sets (P<0.001). The allogeneic transplantation results suggested that it is possible to prolong transplant engraftment by completely matching the DLA genotype between the donor and recipient. Additionally, the MLR assay may be used as a simplified in vitro method to select donors.

Partial sequence analyses of exon 7 of the ABO locus of cynomolgus (Macaca fascicularis) and rhesus (M. mulatta) macaques: Indeterminate phenotypes show the presence of the O blood group.

Compatibility tests to identify A, B, and O alleles are critical for establishing suitable donor-recipient matches among experimental animals. Using a qPCR-based SNP probe assay, we have identified A, B, AB, and indeterminate blood group phenotypes in cynomolgus and rhesus macaques. We have hypothesized, albeit without molecular confirmation, that the indeterminate phenotype represents homozygosity for the null O allele at the macaque ABO locus. The indeterminate phenotype represents the unsuccessful detection of either A or B alleles using primers targeting the A-specific and B-specific single nucleotide polymorphisms (SNPs) in a variable region of exon 7 of the ABO locus. These SNPs are associated with two functional sites, detected using two allele-specific probes in the qPCR assay where the codons leucine and methionine (at codon 266) and glycine and alanine (at codon 268) are required for the synthesis of the A and B transferases, respectively. While reference sequences for the A and B alleles exhibited no novel mutations in the functional exon, plasmid Sanger sequence analyses showed unique mutations within the diagnostic target sites in 10 macaques exhibiting the indeterminate phenotype. Eight of these indeterminate individuals exhibited SNPs at codon 268 that should prevent the syntheses of an A or B transferase. While the two other indeterminate samples had functional codons that were consistent with A or B alleles, mutations in either their probe- or primer-binding sites that altered their peptide sequences probably impeded their detection by our assay.

Canine DLA-79 gene: an improved typing method, identification of new alleles and its role in graft rejection and graft-versus-host disease.

Developing a preclinical canine model that predicts outcomes for hematopoietic cell transplantation in humans requires a model that mimics the degree of matching between human donor and recipient major histocompatibility complex (MHC) genes. The polymorphic class I and class II genes in mammals are typically located in a single chromosome as part of the MHC complex. However, a divergent class I gene in dogs, designated dog leukocyte antigen-79 (DLA-79), is located on chromosome 18 while other MHC genes are on chromosome 12. This gene is not taken into account while DLA matching for transplantation. Though divergent, this gene shares significant similarity in sequence and exon-intron architecture with other class I genes, and is transcribed. Little is known about the polymorphisms of DLA-79 and their potential role in transplantation. This study was aimed at exploring the reason for high rate of rejection seen in DLA-matched dogs given reduced intensity conditioning, in particular, the possibility that DLA-79 allele mismatches may be the cause. We found that about 82% of 407 dogs typed were homozygous for a single, reference allele. Owing to the high prevalence of a single allele, 87 of the 108 dogs (∼80%) transplanted were matched for DLA-79 with their donor. In conclusion, we have developed an efficient method to type alleles of a divergent MHC gene in dogs and identified two new alleles. We did not find any statistical correlation between DLA-79 allele disparity and graft rejection or graft-versus-host disease, among our transplant dogs.

SLA-DRB1 and -DQB1 genotyping by the PCR-SSOP-Luminex method.

A simple and novel genotyping method was developed to detect alleles at the swine leukocyte antigen (SLA)-DRB1 and -DQB1 class II loci by using polymerase chain reaction (PCR)-fluorescently labeled sequence-specific oligonucleotide probes (SSOPs) and Luminex 100 xMAP detection. The PCR-SSOP-Luminex method exhibited accuracy of 95% for both SLA-DRB1 and -DQB1 in 6 homozygous and 16 heterozygous pig samples as confirmed by sequencing the PCR products of the same samples. In addition, 12 low-resolution SLA class II haplotypes consisting of 7 and 9 DRB1 and DQB1 alleles were identified, respectively, in one population of 283 Landrace pigs. This genotyping method facilitates the rapid and accurate identification of two- or four-digit alleles at the SLA-DRB1 and -DQB1 loci.

An improved method for dog leukocyte antigen 88 typing and two new major histocompatibility complex class I alleles, DLA-88*01101 and DLA-88*01201.

Development of preclinical dog models of solid organ and hematopoietic transplantation is critically dependent upon characterization of the polymorphic major histocompatibility complex class I and class II loci. While the class II alleles are easily typed as the polymorphic positions reside on a single exon, typing the class I locus is tedious. We have improved the class I typing method by designing improved primers and adopting alternative DNA amplification and cloning reagents that circumvent the use of radioactivity and the need for the single-stranded conformation polymorphism gels. The method is reliable in typing dogs for the class I dog leukocyte antigen (DLA)-88 locus, and through its use, we describe here two new alleles DLA-88*01101 and DLA-88*01201.

Renal allograft histopathology in dog leukocyte antigen mismatched dogs after renal transplantation.

OBJECTIVE: To evaluate allograft histopathology in dog leukocyte antigen (DLA)-mismatched dogs undergoing renal transplantation, with transient immunosuppression. STUDY DESIGN: Prospective study. ANIMALS: Ten healthy adult mongrel dogs. METHODS: Reciprocal renal transplantation and bilateral nephrectomy were performed. Immune conditioning consisted of nonmyeloablative (200 cGy), total body irradiation (TBI), bone marrow transplantation (BMT; 7 dogs), cyclosporine (CSA; 15 mg/kg every 12 hours), mycophenolate mofetil (MMF; 10 mg/kg every 12 hours) and intermittent prednisone (1 mg/kg every 12-24 hours). Biopsies were collected at transplantation, during full immunosuppression (44-90 days), and once medications were reduced or discontinued (228-580 days). Biopsies were evaluated for interstitial, tubular, vascular, and glomerular lesions. Blood urea nitrogen, creatinine, serum CSA concentrations, and clinical score were determined at each biopsy. RESULTS: Seven dogs survived >200 days (mean, 380 days). Transient CSA toxicity was suspected in 6 dogs. Lymphocytic, plasmacytic interstitial inflammation, and tubulitis progressed when immunosuppressive medications were decreased. All 7 dogs had histologic lesions consistent with some degree of allograft rejection at study end. CONCLUSION: Nonmyeloablative TBI, BMT, and short-term immunosuppression with CSA, MMF, and prednisone allowed renal allograft function and dog survival for >200 days. It appears unlikely that total drug withdrawal will be possible in unrelated DLA-mismatched dogs using this protocol. CLINICAL RELEVANCE: Transient immunosuppression with MMF, CSA, and prednisone along with BMT and nonmyeloablative TBI may make kidney transplantation a clinical reality for treatment of kidney failure in dogs. Initiating both MMF and CSA at lower dosages may potentially eliminate early renal allograft injury.

High-resolution characterization of the canine DLA-DRB1 locus using reference strand-mediated conformational analysis.

Several methods exist for genotyping class II DLA gene polymorphisms in the dog. The most accurate method is sequence-based typing, which involves direct sequencing of polymerase chain reaction products. However, this method is expensive and unsuitable for large-scale studies. Recently, reference strand-mediated conformation analysis (RSCA) has been shown to be effective for characterizing major histocompatibility complex genes in humans, sheep, horse, and cats. RSCA is a cheap and rapid method, ideal for large epidemiological studies. We have developed RSCA for typing DLA-DRB1 in the dog. Control panels including dogs typed by sequence-based typing and cloned major histocompatibility complex class II alleles in plasmids were used to establish migration patterns for each allele using 20 different fluorescent labeled references, of which 5 were selected to allow for clear identification and discrimination of all known DLA-DRB1 alleles. We have compared 168 dogs typed by RSCA for DLA-DRB1 and characterized by sequence-based typing, with less than 1% discrepancy. These differences were due to missing alleles because of a weak polymerase chain reaction. To date, we have RSCA-typed 1,394 dogs. RSCA is likely to become the method of choice for characterizing DLA genes in the dog and will prove a useful tool for dissecting the immune response of dogs in clinical studies.

Production and evaluation of alloantibodies against sheep MHC Class I antigens.

In this work more than 600 sera obtained from three different sources (parous ewes and directed immunizations with whole blood or leucocytes) were tested for cytotoxic antilymphocyte antibodies. A high incidence of cytotoxic antibodies in pregnancy-stimulated animals was confirmed. For the sake of comparison, a comprehensive review of other studies in sheep and other species was performed. There are several different reasons that could explain the differences found between these studies, among them the time of sampling and the cytotoxic assay procedures. Moreover, antibodies were also found in non-pregnant females which may imply that pregnancy is not the only stimulus for antibody production and environmental factors, such as molecular mimicry between infectious agents and lymphocyte antigens, could be the reason for their appearance. In the case of alloimmunizations with leucocytes or whole blood the results were very close to those obtained in goats. Taking into account the Strength Index, the immunization sera were of higher quality. Our results support the methodology of Nesse and Larsen since one injection of whole blood of the lamb is an easy procedure that produces alloantisera with a high value for major histocompatibility complex Class I antigens typing.

Method of lymphocytotoxic crossmatch test for feline renal transplantation.

The optimal condition for methods of lymphocytotoxic crossmatch test for feline renal transplantation was investigated. On separation of viable lymphocytes from whole blood, the best results were obtained when Ficoll-diatrizoate with 1.078 of a specific gravity at 20 degrees C was centrifuged with 800 x g for 30 min at 4 degrees C. A nylon wool column was used to separate T and B cells from lymphocyte fraction. The ratio of T cells in nylon wool effluent cells was 95%, while the ratio of B cells in adherent cells was 41%. Lymphocytotoxic crossmatch tests were performed by using the effluent cells as T cells and the adherent cells as B cells, at 37 degrees C (warm) and 4 degrees C (cold). The ratio of B cells in adherent cells was low, however, the result was utilized as a matching test before transplantation by combining with the T cell result. The trypan blue stain method made it easier than the eosin stain method to distinguish living and dead cells. The lymphocytotoxic crossmatch tests were performed on 15 pairs of healthy cats, and only one pair showed doubtful positive against anti-B cell cold antibodies. During acute rejection after renal transplantation in two pairs which were negative on any anti-lymphocyte antibodies before the transplantation, the anti-T cell warm antibodies became positive in both pairs, and the anti-T cell cold antibodies became positive on one of the two pairs.

Organization of the canine major histocompatibility complex: current perspectives.

The dog is a valuable model for studying several human diseases as well as one of the most important models for organ transplantation. Important to understanding the pathophysiology or development of some of these diseases is an understanding of the canine major histocompatibility complex (MHC) or dog leukocyte antigen (DLA). Initial characterization of the DLA involved primarily cellular, serological, and biochemical analyses. Later a molecular analysis of the DLA region was begun. There are at least four complete class I genes: DLA-88, DLA-12, DLA-64, and DLA-79. DLA-88 is highly polymorphic, with more than 40 alleles obtained from an examination of 50 mixed breed dogs. The other class I loci are less polymorphic, with fewer than 12 alleles each. In the class II region there is one complete DRB gene called DLA-DRB1 with at least 24 alleles and one full-length DQB gene, DLA-DQB1, with 20 alleles characterized to date. DLA-DQA is less polymorphic with nine alleles and DLA-DRA appears monomorphic. Two highly polymorphic canine microsatellite markers, one located in the class I region and one located in the class II region, can be used to identify DLA-matched and -mismatched dogs within families for organ transplantation experiments. Future projects include mapping the DLA region by pulsed-field gel electrophoresis and using a recently constructed canine bacterial artificial chromosome (BAC) library to search for new genes within the DLA. The dog has been a useful model for understanding several human diseases such as gluten-sensitive enteropathy (Hall and Batt 1990), rheumatoid arthritis (Halliwell et al. 1972), narcolepsy (Tafti et al. 1996), and systemic lupus erythematosus (Lewis and Schwartz 1971, Teichner et al. 1990), as well as an important model for solid organ and hematopoietic stem cell transplantation (Storb and Deeg 1985). Much of the impetus behind efforts to characterize the canine MHC comes from its importance in transplantation. In spite of the dog's importance in studying human disease and in immunology, molecular analysis of the DLA has lagged behind that of the mouse and human as well as several agricultural animals.

Denaturing gradient gel electrophoresis: a rapid method for differentiating BoLA-DRB3 alleles.

The products of the BoLA-DRB3 locus are important molecules in the bovine immune response. Several techniques have been used to study and define this locus but they are generally time consuming and limited in their ability to detect novel alleles. In this study we used denaturing gradient gel electrophoresis (DGGE), and direct sequencing, for BoLA-DRB3-typing. First, modified locus-specific primers were used in polymerase chain reaction (PCR) to amplify a 240 bp fragment of exon 2 of BoLA-DRB3 from the genomic DNA of 22 cattle and one pair of twin calves. The reverse primer included a GC-rich clamp to improve the physical separation of the BoLA-DRB3 alleles by DGGE. The denaturing gradient needed to produce separation of alleles was determined using perpendicular DGGE, and this gradient was then applied to parallel denaturing gels. The optimal time for producing allele separation was determined using a time-series analysis. The bands representing individual BoLA-DRB3 alleles were excised from the gels, reamplified, and the nucleotide sequence determined using fluorescent-based automated cycle sequencing. The nucleotide sequences of the separated bands were then compared to published BoLA-DRB3 alleles. A gradient of 10-15% acrylamide combined with a 15-50% ureaformamide gradient was successfully used to separate BoLA-DRB3 alleles in all individuals examined. Nucleotide sequencing showed that the 24 animals possessed 13 BoLA-DRB3 alleles, all of which have been previously described. The BoLA-DRB3 genotypes included 20 heterozygotes and two homozygotes. Three BoLA-DRB3 alleles were seen in each of the twin calves, possibly due to leukochimerism. The technique is reliable and rapid, and avoids cloning alleles prior to nucleotide sequencing and therefore offers distinct advantages over previous techniques for BoLA-DRB3-typing.

Histocompatibility testing of dog families with highly polymorphic microsatellite markers.

The dog has served traditionally as a model for marrow and organ transplantation. A key component of any study of transplantation is histocompatibility typing of donors and recipients. Towards the development of a less expensive, more simplified typing system within canine families, a new highly polymorphic microsatellite marker for the canine Major Histocompatibility Complex class II region was isolated and characterized. In addition, we report on the application of class I and class II microsatellite-based markers for following the inheritance of the alleles within the canine analog of the human HLA loci, DLA, through multi-generation pedigree.

Effect of climatic stress on the immunological reactivity of weaned pigs.

Weaned pigs exposed daily to either unpredictable draught (experiment 1) or intermittent unpredictable draught (experiment 2) showed different lymphocyte blastogenic responses after mitogenic stimulation with phytohaemagglutinin (PHA) and concanavalin A (ConA). In both experiments PHA skin test responses were lower for draught exposed pigs than for control pigs and leucocyte numbers or profiles were altered compared to those of control pigs. Superoxide production and chemiluminescence of porcine granulocytes were similar for draught exposed and control animals. Furthermore, serum globulin content did not differ significantly between pigs in the experimental and control room. The strong increase in serum gamma-globulin after the Aujeszky Disease Virus (ADV)-challenge was the same for draught exposed and control pigs. The same held for the lymphocyte blastogenic response with ADV protein as antigenic stimulus. The present study shows the effects of climatic stress on immunological reactivity, which may reflect a homeostatic disturbance of the pig's immune system elicited by exposure to unpredictable draught.

Restriction fragment length polymorphism analysis of the chicken B-F and B-L genes and their association with serologically defined B haplotypes.

Seven serologically defined chicken haplotypes have been analysed by restriction fragment length polymorphism (RFLP) with chicken cDNA probes specific for MHC class I and II. The results demonstrate an excellent correlation between the observed RFLP banding patterns in the investigated haplotypes and the serological B-typing. In future, RFLP analysis in addition to serological B-typing may sharpen the tools in the search for recombinant chromosomes separating B-F and B-L.

A study of BoLA class II antigens with BoT4+ T lymphocyte clones.

It has hitherto proved difficult to phenotype cattle for class II histocompatibility antigens using standard serological techniques because of problems of reagent specificity and antigen expression on peripheral blood mononuclear cells (PBMs). We recently described the production of class II-specific alloreactive bovine T cell clones characterized by the BoT4+ phenotype. In this report we describe studies of the application of four such clones, derived from a single mixed leucocyte culture (MLC), for class II phenotyping in proliferation and cytotoxicity assay systems. Proliferation assays used irradiated PBM as stimulator cells and cytotoxicity assays used Theileria parva-infected lymphoblastoid cells as targets. Proliferation assays revealed three distinct specificities among the four clones indicating that they detected three different class II determinants. Furthermore, in a family study, the genes encoding the determinants recognized by the clones were found to be linked to the gene encoding the w10 class I A locus product on one of the w10-bearing haplotypes in our study population. Two of the clones were studied in cytolysis assays. Lack of cytolysis of one of the targets, which was derived from the PBM of an animal carrying a class II determinant detected in proliferation assay, was explained by the total lack of expression of class II antigens on the target cell line in question, as determined with 4 class II-specific monoclonal antibodies (mAb). We conclude that BoT4+ alloreactive clones provide a potentially useful and particularly discriminating way of detecting polymorphic class II antigens of cattle, especially when applied in assays of proliferative response to PBM.

Effects of tissue antigen matching on the healing of fresh cancellous bone allografts in dogs.

The radiographic and histologic healing patterns of fresh cancellous bone allografts were compared with those of fresh cancellous autografts in dogs. Two groups of allografts were studied: 1 group of littermate pairs with minor histocompatibility mismatches, and 1 group of unrelated pairs with major histocompatibility mismatches. Pairs were chosen on the basis of preoperative serologic typing and mixed lymphocyte cultural assay of lymphocyte-defined compatibility. Generally, grafts with minor mismatches and autografts achieved bony union in 6 weeks with grafted bone serving as a scaffold for new bone formation. Grafts with major mismatches were resorbed and replaced by fibrocartilage. Healing of osteotomy sites grafted with mismatched bone occurred by ingrowth of host periosteal and endosteal new bone.

Studies of histocompatibility and immune response of chickens selected for resistance and susceptibility to Marek's disease.

Two sets (four lines) of chickens, lines 7 and 6 and lines P and N, the former of each set susceptible and the latter resistant to Marek's disease, were examined for their relative histocompatibility and immunocompetence. Results from the in vivo graft-versus-host response splenomegaly assay, and graft-versus-host chorioallantoic membrane pock formation assay confirmed the within-line, B-locus homozygosity of chickens of lines 7, 6, and N and the heterozygosity of line-P chickens. These assays further confirmed that line-7 and line-6 chickens share identical alleles at the major histocompatibility locus. The capacity of the lines of chickens to elicit specific cell-mediated immune lysis as measured by the release of chromium 51 generally agreed with the in vivo graft-versus-host responses. These data demonstrate that the 51Cr-release assay is a reliable measure of histocompatibility within the avian system.