Genomic identification of the minor histocompatibility antigen HA-1 locus by allele-specific PCR

A Short History of Skin Grafting in Burns: From the Gold Standard of Autologous Skin Grafting to the Possibilities of Allogeneic Skin Grafting with Immunomodulatory Approaches

Due to groundbreaking and pioneering developments in the last century, significant improvements in the care of burn patients have been achieved. In addition to the still valid therapeutic standard of autologous split-thickness skin grafting, various commercially available skin substitutes are currently available. Significant progress in the field of tissue engineering has led to the development of promising therapeutic approaches. However, scientific advances in the field of allografting and transplant immunology are of great importance. The achievement of various milestones over the past decades has provided thought-provoking impulses in the field of skin allotransplantation. Thus, biologically viable skin allotransplantation is still not a part of the clinical routine. The purpose of this article is to review the achievements in burn surgery with regards to skin allotransplantation in recent years.

Molecular typing methods for minor histocompatibility antigens

Minor histocompatibility (H) antigen mismatching leads to clinically relevant alloimmune reactivity. Depending on the tissue expression pattern of the involved minor H antigens, the immune response may either cause graft-versus-host disease and a graft-versus-tumor effect or lead to only a graft-versus-leukemia effect. Thus, identification of recipient-donor pairs with minor H antigen mismatches has clinical importance. This chapter describes molecular typing methods for molecular typing of minor H antigens.

Minor histocompatibility antigens are expressed in syncytiotrophoblast and trophoblast debris: implications for maternal alloreactivity to the fetus

The fetal semi-allograft can induce expansion and tolerance of antigen-specific maternal T and B cells through paternally inherited major histocompatibility complex and minor histocompatibility antigens (mHAgs). The effects of these antigens have important consequences on the maternal immune system both during and long after pregnancy. Herein, we investigate the possibility that the placental syncytiotrophoblast and deported trophoblastic debris serve as sources of fetal mHAgs. We mapped the expression of four mHAgs (human mHAg 1, pumilio domain-containing protein KIAA0020, B-cell lymphoma 2-related protein A1, and ribosomal protein S4, Y linked) in the placenta. Each of these proteins was expressed in several placental cell types, including the syncytiotrophoblast. These antigens and two additional Y chromosome-encoded antigens [DEAD box polypeptide 3, Y linked (DDX3Y), and lysine demethylase5D] were also identified by RT-PCR in the placenta, purified trophoblast cells, and cord blood cells. Finally, we used a proteomic approach to investigate the presence of mHAgs in the syncytiotrophoblast and trophoblast debris shed from first-trimester placenta. By this method, four antigens (DDX3Y; ribosomal protein S4, Y linked; solute carrier 1A5; and signal sequence receptor 1) were found in the syncytiotrophoblast, and one antigen (DDX3Y) was found in shed trophoblast debris. The finding of mHAgs in the placenta and in trophoblast debris provides the first direct evidence that fetal antigens are present in debris shed from the human placenta. The data, thus, suggest a mechanism by which the maternal immune system is exposed to fetal alloantigens, possibly explaining the relationship between parity and graft-versus-host disease.

Peptide length extension skews the minor HA-1 antigen presentation toward activated dendritic cells but reduces its presentation efficiency

Minor histocompatibility Ags (mHags) are important targets of the graft-versus-leukemia effect after HLA-matched allogeneic stem cell transplantation. mHags are HLA-restricted polymorphic peptides expressed on normal and leukemia cells. Vaccination with hematopoiesis-restricted mHag peptides, such as HA-1, may boost the graft-versus-leukemia effect. However, some animal studies indicate that peptides exactly reflecting immunogenic T cell epitopes (short peptides [SPs]) induce tolerance that is potentially due to systemic Ag spreading. Peptide length extension (long peptides [LPs]) may optimize immune responses by restricting and prolonging Ag presentation on dendritic cells (DCs). In this study, we compared the in vitro characteristics and T cell-stimulatory capacities of a human 30-mer HA-1 LP with the 9-mer HA-1 SP. DCs presented the HA-1 LP and SP and expanded HA-1-specific cytotoxic T cell lines. As hypothesized, HA-1 LP presentation, but not SP presentation, was largely restricted to activated DCs and was nearly absent on other hematopoietic cells. However, DCs presented the HA-1 LP 2-3 log levels less efficiently than the SP. Finally, the decay of HA-1 LP and SP presentation on DCs was comparable. We conclude that HA-1 LP and SP differ in their in vitro characteristics and that only comparative clinical studies after allogeneic stem cell transplantation may reveal the optimal HA-1 vaccine.

Does minor histocompatibility antigen HA-1 disparity affect the occurrence of graft-versus-host disease in tunisian recipients of hematopoietic stem cells?

INTRODUCTION

Minor histocompatibility antigen HA-1 (MiHAg-HA-1) disparity between a patient and his or her human leukocyte antigen (HLA) genoidentical donor has been widely associated with an increased risk of graft-versus-host disease following allogeneic hematopoietic stem cell transplantation.

OBJECTIVE

To examine the effect of HA-1 disparity on the incidence of both acute and chronic graft-versus-host disease in Tunisian recipients of hematopoietic stem cells.

METHODS

A total of 60 patients and their 60 respective sibling hematopoietic stem cell donors were enrolled in this study. All patients prophylactically received cyclosporine A and/or methotrexate for graft-versus-host disease. An HA-1 genotyping assay was performed with the SSP-PCR method, and HLA-A*0201- and/or HLA-A*0206-positive samples were identified using the Luminex HLA typing method.

RESULTS

The Luminex HLA typing assay showed that 54 patients were positive for either the HLA-A*0201 or HLA-A*0206 alleles. Among these cases, six pairs were mismatched for MiHAg-HA-1. Both acute and chronic graft-versus-host disease occurred in four mismatched patients (Fisher's p-values were 0.044 and 0.170, respectively). A univariate logistic regression model analysis showed that only acute graft-versus-host disease may be affected by recipient MiHAg-HA-1 disparity (p: 0.041, OR: 6.727), while chronic graft-versus-host disease correlates with both age and recipient/donor sex mismatch (p: 0.014, OR: 8.556 and p: 0.033, OR: 8.664, respectively).

CONCLUSION

Our findings support previously reported data suggesting a significant association between HA-1 disparity and the risk of acute graft-versus-host disease following hematopoietic stem cell transplantation.

Hypomethylating drugs convert HA-1-negative solid tumors into targets for stem cell-based immunotherapy

Clinical responses of solid tumors after allogeneic human leukocyte antigen-matched stem cell transplantation (SCT) often coincide with severe graft-versus-host disease (GVHD). Targeting minor histocompatibility antigens (mHags) with hematopoiesis- and cancer-restricted expression, for example, HA-1, may allow boosting the antitumor effect of allogeneic SCT without risking severe GVHD. The mHag HA-1 is aberrantly expressed in cancers of most entities. However, an estimated 30% to 40% of solid tumors do not express HA-1 (ie, are HA-1(neg)) and cannot be targeted by HA-1-specific immunotherapy. Here, we investigated the transcriptional regulation of HA-1 gene expression in cancer. We found that DNA hypermethylation in the HA-1 promoter region is closely associated with the absence of HA-1 gene expression in solid tumor cell lines. Moreover, we detected HA-1 promoter hypermethylation in primary cancers. The hypomethylating agent 5-aza-2'-deoxycytidine induced HA-1 expression only in HA-1(neg) tumor cells and sensitized them for recognition by HA-1-specific cytotoxic T lymphocytes. Contrarily, the histone deacetylation inhibitor trichostatin A induced HA-1 expression both in some HA-1(neg) tumor cell lines and in normal nonhematopoietic cells. Our data suggest that promoter hypermethylation contributes to the HA-1 gene regulation in tumors. Hypomethylating drugs might extend the safe applicability of HA-1 as an immunotherapeutic target on solid tumors after allogeneic SCT.

Molecular typing methods for minor histocompatibility antigens

Minor histocompatibility (H) antigens crucially affect the outcome of human leukocyte antigen-matched allogeneic stem cell transplantation. The number of molecularly identified minor H antigens is rapidly increasing. In parallel, clinical implementation of minor H antigens for immunotherapy has gained significant interest. It is therefore timely to type stem cell transplant recipients and their donors for minor H antigens. Here, we summarize all the currently known methodologies for minor H antigen typing on the genomic and on the RNA level.

HA-1 Mismatch Has Significant Effect in Chronic Allograft Nephropathy in Clinical Renal Transplantation

BACKGROUND

The minor histocompatibility antigen HA-1 occurs in two allelic forms: H and R. The HA-1(H) form presented in the context of HLA A2 can elicit specific cytotoxic lymphocyte (CTL) responses and can cause graft-versus-host disease in marrow transplants. However, its significance in solid organ transplants is unknown. We determined whether incompatibility of the HA-1 resulted in enhanced rejection and whether HA-1 specific CTLs were generated.

MATERIALS AND METHODS

HLA A2-matched donor/recipient pairs were selected and typed for HA-1 antigens by polymerase chain reaction. Nineteen of 81 pairs were mismatched for HA-1. Peripheral blood mononuclear leucocytes from five recipients, HLA A2 DR-matched with donors, were stimulated for 3 days with third-party donor, matched for HLA A2 DR but mismatched for HA-1. Cells were stained for surface markers, HA-1(H)-specific tetramer reagent, and analyzed by flow cytometry. Controls were unstimulated cells; PBML from two patients never exposed to HA-1(H); immunoglobulin G isotype-matched controls. For all patients, acute rejection rates posttransplant was ascertained. Long-term data was available for 36 patients.

RESULTS AND CONCLUSIONS

There was no difference in acute rejection rates between the HA-1-matched and -mismatched groups, but there was a significant difference in chronic rejection rates, evidenced by increased graft failures during the follow-up period (P = .0024). Lymphocytes from five HA-1-mismatched recipients were stimulated in vitro with cells from HLA-A2 and DR-matched but HA-1-mismatched surrogate donor. Though there seemed to be an excess of tetramer-positive cells, anti-HA-1-specific CTL responses were not conclusively elicited in vitro.

Expression and purification of the minor histocompatibility antigen, HA-1H generated in Escherichia coli

The minor histocompatibility antigen HA-1H is a potential immunotherapeutic molecule. It can be used as a target for graft versus leukaemia reactions to eliminate residual HA-1H expressing leukaemic cells in patients following haemopoietic stem cell transplantation, whereby HA-1H primed donor cells can be transferred into a patient via adoptive immunotherapy. However, thus far only synthetic peptides corresponding to a HLA-A *0201 restricted HA-1H epitope have been used to generate HA-1H specific T cells. We are the first laboratory to clone, express and purify a region of HA-1H using an Escherichia coli expression system. The recombinant HA-1H protein was purified under denaturing conditions and the affinity purification tag removed using thrombin to remove non-specific amino acids. The 92 amino acid recombinant protein was characterised by mass spectrometry. Our rationale is that by using a recombinant HA-1H protein rather than peptide, HA-1H specific T cells may be generated from presentation of multiple HA-1H epitopes complexed in different HLA molecules. A multi-epitope approach may have wider applicability and maybe more effective at leukaemia control. The recombinant HA-1H protein may also be used as a research tool to identify novel CD4(+) helper T cell and CD8(+) cytotoxic T cell epitopes.

A uniform genomic minor histocompatibility antigen typing methodology and database designed to facilitate clinical applications

BACKGROUND

Minor Histocompatibility (H) antigen mismatches significantly influence the outcome of HLA-matched allogeneic stem cell transplantation. The molecular identification of human H antigens is increasing rapidly. In parallel, clinical application of minor H antigen typing has gained interest. So far, relevant and simple tools to analyze the minor H antigens in a quick and reliable way are lacking.

METHODOLOGY AND FINDINGS

We developed a uniform PCR with sequence-specific primers (PCR-SSP) for 10 different autosomal minor H antigens and H-Y. This genomic minor H antigen typing methodology allows easy incorporation in the routine HLA typing procedures. DNA from previously typed EBV-LCL was used to validate the methodology. To facilitate easy interpretation for clinical purposes, a minor H database named dbMinor (http://www.lumc.nl/dbminor) was developed. Input of the minor H antigen typing results subsequently provides all relevant information for a given patient/donor pair and additional information on the putative graft-versus-host, graft-versus-tumor and host-versus-graft reactivities.

SIGNIFICANCE

A simple, uniform and rapid methodology was developed enabling determination of minor H antigen genotypes of all currently identified minor H antigens. A dbMinor database was developed to interpret the genomic typing for its potential clinical relevance. The combination of the minor H antigen genomic typing methodology with the online dbMinor database and applications facilitates the clinical application of minor H antigens anti-tumor targets after stem cell transplantation.

Role of non-HLA genetic polymorphisms in graft-versus-host disease after haematopoietic stem cell transplantation

Graft-versus-host disease (GvHD) is the main complication after haematopoietic stem cells transplantation (HSCT) and acute forms (aGvHD) occur in 20-40% of cases even after donor (D) and recipient (R) HLA matching, apparently because of D/R minor histocompatibility antigen (mHA) mismatches and cytokine polymorphisms. The genotype of cytokines and mHA of 77 haematological R following HSCT from HLA identical siblings were determined to detect genetic polymorphisms correlated with GvHD. We analysed TNFA (-863 C/A, -857 C/T and G/A at positions -574, -376, -308, -244, -238), IL-10 (-1082 G/A, -819 C/A, -592 C/T), IL-1B (T/C +3953), IL-1RA (VNTR), HA-1 (H/R allele) and CD-31 (C/G at codon 125, A/G at codon 563). Allele frequencies were in Hardy-Weinberg equilibrium and similar to those of 77 healthy controls. We observed positive correlations between a lower risk of clinically significant aGvHD and both the presence of -1082G -819C -592C IL-10 haplotype when both R and D are considered together and the absence of R IL-1RA allele 2. Furthermore, we observed an association between the absence of TNF-A -238 A allele and the risk of extensive chronic GvHD. mHA and cytokines genotyping would thus seem a valid source of information for the prior identification of recipients with a higher risk of aGvHD.

Minor histocompatibility antigens: from transplantation problems to therapy of cancer

The idea of transferring healthy marrow for the therapeutic treatment of the various diseases of the blood and of the immune system made a significant contribution to controlling diseases and to advancing modern clinical sciences. The first series of bone marrow transplantations in the 1960s were confronted with severe complications. It became clear that matching for the human leukocyte antigen (HLA) system between donor and recipient significantly improved the clinical results. Nonetheless, an unacceptable percentage of severe complications remained that is mainly attributable to non-HLA histocompatibility systems, i.e., minor histocompatibility antigens. Observations in the 1970s that minor histocompatibility antigens cause serious problems in human bone marrow transplantation laid the basis for their use as curative antigens in stem cell transplantation to date. Thus, the allo-immune T cell activities caused by minor histocompatibililty antigen disparities between HLA-matched donor and recipient can now be applied for the benefit of the transplant patient.

Therapeutic and Diagnostic Applications of Minor Histocompatibility Antigen HA-1 and HA-2 Disparities in Allogeneic Hematopoietic Stem Cell Transplantation: A Survey of Different Populations

Minor histocompatibility antigens (mHags) HA-1 and HA-2 are encoded by biallelic loci, with immunogenic variants, HA-1H and HA-2V, which induce strong HLA-A2-restricted alloreactive T-cell responses, and nonimmunogenic counterparts, HA-1R and HA-2M, which represent functional null alleles that are poorly presented by HLA class I molecules. HA-1 and HA-2 are potential targets of selective graft-versus-leukemia and graft-versus-tumor reactivity after allogeneic hematopoietic stem cell transplantation (HSCT); however, these applications are restricted to a limited number of patients. Here, we show that a far more frequent application of HA-1 and HA-2 disparity relies on their use as markers for the state of host chimerism after allogeneic HSCT. We have determined allelic frequencies of 29.3% and 70.7% for HA-1H and HA-1R, respectively, and of 83.7% and 16.3% for HA-2V and HA-2M, respectively, in >200 healthy individuals from northern Italy. Similar frequencies were observed in nearly 100 patients affected by hematologic malignancies or solid tumors, thus showing that HA-1 and HA-2 variability are not associated with the presence of cancer. On the basis of these data, we predict that HA-1 and HA-2 can be used in 32.8% and 23.5% of Italian transplant patients, respectively, as markers for the state of host chimerism, whereas exploitation of disparity for these mHags for targeted immunotherapy will be possible in 10.7% and 1.1% of Italian patients, respectively. Retrospective HA-2 typing of bone marrow aspirates obtained from a patient during complete remission or recurrence of acute myeloid leukemia after haploidentical HSCT showed the feasibility of using HA-2 as a surrogate marker for disease monitoring. Because of an apparent north-south gradient for HA-1 allelic frequencies, with higher frequencies for the HA-1H variant reported in white populations from Southern Europe as compared with Northern Europe and North America, the diagnostic applicability of HA-1 disparity will be slightly more frequent in transplant patients from the north. Taken together, our data show that determination of HA-1 and HA-2 variability can be an important parameter for the selection of allogeneic stem cell donors, in particular for patients affected by hematologic malignancies without a tumor-specific molecular marker.

Sequence diversity within the HA-1 gene as detected by melting temperature assay without oligonucleotide probes

BACKGROUND

The minor histocompatibility antigens (mHags) are self-peptides derived from common cellular proteins and presented by MHC class I and II molecules. Disparities in mHags are a potential risk for the development of graft-versus-host disease (GvHD) in the recipients of bone marrow from HLA-identical donors. Two alleles have been identified in the mHag HA-1. The correlation between mismatches of the mHag HA-1 and GvHD has been suggested and methods to facilitate large-scale testing were afterwards developed.

METHODS

We used sequence specific primer (SSP) PCR and direct sequencing to detect HA-1 gene polymorphisms in a sample of 131 unrelated Italian subjects. We then set up a novel melting temperature (Tm) assay that may help identification of HA-1 alleles without oligonucleotide probes.

RESULTS

We report the frequencies of HA-1 alleles in the Italian population and the presence of an intronic 5 base-pair deletion associated with the immunogeneic allele HA-1H. We also detected novel variable sites with respect to the consensus sequence of HA-1 locus. Even though recombination/gene conversion events are documented, there is considerable linkage disequilibrium in the data. The gametic associations between HA-1R/H alleles and the intronic 5-bp ins/del polymorphism prompted us to try the Tm analysis with SYBR Green I. We show that the addition of dimethylsulfoxide (DMSO) during the assay yields distinct patterns when amplicons from HA-1H homozygotes, HA-1R homozygotes, and heterozygotes are analysed.

CONCLUSION

The possibility to use SYBR Green I to detect Tm differences between allelic variants is attractive but requires great caution. We succeeded in allele discrimination of the HA-1 locus using a relatively short (101 bp) amplicon, only in the presence of DMSO. We believe that, at least in certain assets, Tm assays may benefit by the addition of DMSO or other agents affecting DNA strand conformation and stability.

Immunotherapy of cancer through targeting of minor histocompatibility antigens

Minor histocompatibility antigens are allogeneic targets of T-cell mediated graft-versus-tumour effects following allogeneic stem cell transplantation. Recent research has identified several minor histocompatibility antigens as tumour proteins and has also disclosed their unique properties in both the induction and the effector phase of graft-versus-tumour effects. Targeting tumour-specific minor histocompatibility antigens by adoptive immunotherapy will battle against tumour tolerance and evoke allo-immune responses, thereby enhancing graft-versus-tumour effects against leukaemia and solid tumours. Recently acquired knowledge of the role of donor immunisation status, new techniques in the generation of minor histocompatibility antigen-specific cytotoxic T lymphocytes in vitro, and innovative principles in vaccination will help to design clinical trials that exploit minor histocompatibility antigens in the immunotherapy of cancer.

Minor histocompatibility antigen HA-1 and HPA-5 polymorphisms in HLA-identical related bone marrow transplantation

The minor histocompatibility antigens (mHags), HA-1 and HPA-5, are immunogenic alloantigens shown to be responsible for graft-versus-host disease (GVHD) in HLA-identical bone marrow transplantation. Both antigens have two known alleles each, resulting in a single amino acid polymorphism. The HA-1H allele encodes histidine, whereas the HA-1R allele encodes arginine. The HPA-5b (Br(a)) allele encodes lysine, whereas the HPA-5a (Br(b)) encodes glutamic acid. In this study, 49 bone marrow transplant recipients and their genetically related HLA-identical donors were evaluated for the presence of HA-1, whereas 39 recipients, different from the abovementioned ones, and their HLA-identical siblings were analyzed for the presence of HPA-5. The frequencies of the two alleles of HA-1 in the recipient population were HA-1R = 0.663 and HA-1H = 0.336. In the donor population, the respective frequencies were 0.704 and 0.296. Seven donors (14.5%) were mismatched with the recipients for HA-1H. In contrast, the frequencies of the two alleles of HPA-5 in the recipient population were HPA-5a = 0.859 and HPA-5b = 0.141; whereas, among donors, they were 0.820 and 0.180, respectively. Five donors (12.8%) were found to be mismatched with their recipients for HPA-5. These results provide insight into the polymorphism of mH antigens based on the study of their frequencies in bone marrow transplant recipients and their genetically HLA-identical siblings, an endeavor that is essential to investigate the presence of HA-1 and HPA-5 mHags.

Cord blood comprises antigen-experienced T cells specific for maternal minor histocompatibility antigen HA-1

Umbilical cord blood transplantation is applied as treatment for mainly pediatric patients with hematologic malignancies. The clinical results show a relatively low incidence of graft-versus-host disease and leukemia relapse. Since maternal cells traffic into the fetus during pregnancy, we questioned whether cord blood has the potential to generate cytotoxic T cells specific for the hematopoietic minor histocompatibility (H) antigen HA-1 that would support the graft-versus-leukemia effect. Here, we demonstrate the feasibility of ex vivo generation of minor H antigen HA-1-specific T cells from cord blood cells. Moreover, we observed pre-existing HA-1-specific T cells in cord blood samples. Both the circulating and the ex vivo-generated HA-1-specific T cells show specific and hematopoietic restricted lysis of human leukocyte antigen-A2pos/HA-1pos (HLA-A2pos/HA-1pos) target cells, including leukemic cells. The cord blood-derived HA-1-specific cytotoxic T cells are from child origin. Thus, the so-called naive cord blood can comprise cytotoxic T cells directed at the maternal minor H antigen HA-1. The apparent immunization status of cord blood may well contribute to the in vivo graft-versus-leukemia activity after transplantation. Moreover, since the fetus cannot be primed against Y chromosome-encoded minor H antigens, cord blood is an attractive stem cell source for male patients. (Blood. 2005;105:1823-1827)

Recipient mHag-HA1 disparity and aGVHD in thalassemic-transplanted patients

In order to determine the influence of HA-1 minor histocompatibility antigen mismatch on BMT outcome, we analyzed a pool of 94 thalassemic transplanted patients all selected for the presence of HLA-A(*)0201 allele. The HA-1 typing was performed using SSP analysis. All the patients received bone marrow from HLA-identical MLC nonresponsive siblings. As graft-versus-host-disease (GVHD) prophylaxis, all patients received cyclosporin and short methotrexate. Grades II-IV GVHD occurred in five (33.3%) of the 15 patients with recipient HA-1 disparity compared with 14 (17.7%) of the 79 patients without HA-1 disparity. Despite the higher incidence of acute graft-versus-host-disease (aGVHD) in the group of patients with HA-1 incompatibility, these data were not statistically significant. However, it was interesting to observe that no GVHD developed in any of the 15 cases in which the recipient was HA-1 negative and the donor HA-1 positive.

Quantification of donor and recipient hemopoietic cells by real-time PCR of single nucleotide polymorphisms

Analysis of changes in recipient and donor hemopoietic cell origin is extremely useful to monitor the effect of stem cell transplantation (SCT) and sequential adoptive immunotherapy by donor lymphocyte infusions (DLI). We developed a sensitive and accurate method to quantify the percentage of recipient and donor cells by real-time PCR using single nucleotide polymorphisms (SNPs) as markers. Allele-specific PCR of seven SNPs resulted in specific markers for donor or recipient in 97% of HLA-identical sibling pairs. Both, recipient- and donor-derived hemopoietic cells can be simultaneously analyzed in 67% sibling pairs. We expect this can be increased to approximately 99% by developing three additional SNP-PCR. Serial dilution of SNP-positive DNA into either SNP-negative DNA or water revealed a detection limit of 0.1-0.01% depending on the amount of input DNA and start C(t) of the used SNP-PCR. Application of our real-time SNP-PCR method for a CML patient treated by allogeneic SCT and DLI demonstrated its feasibility to follow donor T-cell chimerism and early detection of residual and recurrent autologous hemopoiesis in response to treatment. This detailed monitoring of the genetic origin of hemopoietic cells, in particular immune effector cells and target cells after SCT and DLI, may substantially contribute to understanding of the mechanisms that play a role in the success of treatment.

Recipient cytokine genotypes for TNF-alpha and IL-10 and the minor histocompatibility antigens HY and CD31 codon 125 are not associated with occurrence or severity of acute GVHD in unrelated cord blood transplantation: a retrospective analysis

BACKGROUND

In HLA-identical sibling bone marrow transplantation, certain recipient cytokine gene polymorphism genotypes and minor histocompatibility differences influence the occurrence and severity of acute graft-versus-host disease (aGvHD). The present study investigated the role of cytokine tumor necrosis factor (TNF)-alpha and interleukin (IL)-10 gene polymorphisms HY, HA-1, and CD31 minor histocompatibility antigen (mHag) mismatch in the development of aGvHD after unrelated cord blood (CB) transplant (CBT).

METHODS

DNA samples of 115 CB recipients and their unrelated CB grafts were analyzed for genotype associated with TNF-alpha (TNFd3/d3) and IL-10 (IL-10(-1064), 11-16) and for disparities in major and three minor histocompatibility antigens, HY, HA-1, and CD31 codon 125. Results were correlated with the incidence of aGvHD grades II to IV.

RESULTS

Neither the donor nor the recipient GvHD risk alleles TNFd3/d3 and IL-10(-1064) (11-16) were associated with the development of aGvHD grades II to IV and I to IV. Because of the heterogeneity of CBTs, the data were reanalyzed separately for patients with malignancies (n=83) or with inborn errors (n=24). No significant association was observed between the severity of aGvHD and the possession of either TNFd3/d3 or IL-10 (11-16) genotypes. Mismatches for the mHags HY, HA-1, and CD31 exon 125 between donor and recipient did not associate with aGvHD grades II to IV.

CONCLUSIONS

In contrast to HLA-identical sibling bone marrow transplantation, in mismatched unrelated CBT, neither the cytokine genotypes TNFd3/d3 alone or in combination with IL-10(-1064) alleles nor the minor histocompatibility antigens HY, HA-1, and CD31 exon 125 were associated with aGvHD grades II to IV. Further determination of the cytokine gene polymorphism genotypes in CBTs compared with bone marrow transplants may identify those polymorphisms that could be potential predictive markers for the occurrence of aGvHD.

The hematopoietic system-specific minor histocompatibility antigen HA-1 shows aberrant expression in epithelial cancer cells

Allogeneic stem cell transplantation (SCT) can induce curative graft-versus-tumor reactions in patients with hematological malignancies and solid tumors. The graft-versus-tumor reaction after human histocompatibility leukocyte antigen (HLA)-identical SCT is mediated by alloimmune donor T cells specific for polymorphic minor histocompatibility antigens (mHags). Among these, the mHag HA-1 was found to be restricted to the hematopoietic system. Here, we report on the HA-1 ribonucleic acid expression by microdissected carcinoma tissues and by single disseminated tumor cells isolated from patients with various epithelial tumors. The HA-1 peptide is molecularly defined, as it forms an immunogenic peptide ligand with HLA-A2 on the cell membrane of carcinoma cell lines. HA-1-specific cytotoxic T cells lyse epithelial tumor cell lines in vitro, whereas normal epithelial cells are not recognized. Thus, HA-1-specific immunotherapy combined with HLA-identical allogeneic SCT may now be feasible for patients with HA-1(+) carcinomas.

Induction of HA-1-specific cytotoxic T-cell clones parallels the therapeutic effect of donor lymphocyte infusion

Donor lymphocyte infusions (DLI) can induce a graft-versus-leukaemia (GvL) reaction in patients with relapsed disease. However, the mechanisms involved in remission induction are not completely known. A patient with chemotherapy-refractory relapse 1 year after human leucocyte antigen (HLA)-identical, unrelated stem cell transplantation (SCT) for bcr/abl-positive common acute lymphoblastic leukaemia (ALL) received a DLI from the original donor, and achieved complete cytogenetic and molecular remission concomitantly with extensive graft-versus-host disease (GvHD). Seven CD8+, donor-derived, alloreactive T-cell clones were generated by stimulating post-DLI remission cells with the patient's pretransplant mature dendritic cells. The minor histocompatibility antigen (mHag) recognized by these T-cell clones was identified as HA-1, a mHag associated with acute GvHD after SCT. Our finding provides evidence of HA-1-associated GvL effects after DLI that paralleled the eradication of full-blown, chemotherapy-refractory ALL relapse after allogeneic SCT.

Allele specific PCR for the minor Histocompatibility antigen HA-2

The hematopoietic system restricted minor Histocompatibility antigen (mHag), HA-2, is encoded by the novel human class I Myosin gene, MYO1G, located on the short arm of chromosome 7. The HA-2 encoding region is di-allelic and comprises the HLA-A2 restricted T cell epitope YIGEVLVSV (HA-2V) and its allelic counterpart YIGEVLVSM (HA-2M). We designed a sequence specific PCR (SSP) for both HA-2 alleles. The HA-2 genomic typing results were compared with the HA-2 CTL phenotyping in three families and revealed exact correlation. The mHag HA-2 SSP can be incorporated in DNA based typing protocols.

Disparity for the minor histocompatibility antigen HA-1 is associated with an increased risk of acute graft-versus-host disease (GvHD) but it does not affect chronic GvHD incidence, disease-free survival or overall survival after allogeneic human leucocyte antigen-identical sibling donor transplantation

Disparity for the minor histocompatibility antigen HA-1 between patient and donor has been associated with an increased risk of acute graft-versus-host disease (GvHD) after allogeneic human leucocyte antigen (HLA)-identical sibling donor stem cell transplantation (SCT). However, no data concerning the impact of such disparity on chronic GvHD, relapse or overall survival are available. A retrospective multicentre study was performed on 215 HLA-A2-positive patients who received an HLA-identical sibling SCT, in order to determine the differences in acute and chronic GvHD incidence on the basis of the presence or absence of the HA-1 antigen mismatch. Disease-free survival and overall survival were also analysed. We detected 34 patient-donor pairs mismatched for HA-1 antigen (15.8%). Grades II-IV acute GvHD occurred in 51.6% of the HA-1-mismatched pairs compared with 37.1% of the non-mismatched. The multivariate logistic regression model showed statistical significance (P: 0.035, OR: 2.96, 95% CI: 1.07-8.14). No differences were observed between the two groups for grades III-IV acute GvHD, chronic GvHD, disease-free survival or overall survival. These results confirmed the association between HA-1 mismatch and risk of mild acute GvHD, but HA-1 mismatch was not associated with an increased incidence of chronic GvHD and did not affect relapse or overall survival.

Donor-recipient incompatibility at CD31-codon 563 is a major risk factor for acute graft-versus-host disease after allogeneic bone marrow transplantation from a human leucocyte antigen-matched donor

Disparities at minor histocompatibility antigens (mHA) are thought to be responsible for acute graft-versus-host disease (aGVHD) in patients receiving bone marrow transplantation (BMT) from a human leucocyte antigen (HLA)-matched donor. Although some mHA have been identified in humans, their role in aGVHD has not. Patients (n = 150) receiving a BMT from an HLA-matched donor were investigated for a correlation between aGVHD and donor/recipient incompatibility for seven polymorphisms previously proposed for mHA (HA-1, H-Y, CD31-codon 125, CD31-codon 563, HPA-1, HPA-3 and HPA-5). Only mismatch at CD31-codon 563 predicted grade II-IV aGVHD. The risk derived from CD31-codon 563 mismatch was the same as that derived from the use of bone marrow from an unrelated donor. We suggest that donor/recipient compatibility at CD31-codon 563 should be added to HLA-typing for donor selection and/or adjustment of aGVHD prophylaxis.

The relationship between HA-1 compatibility and the activation of helper T lymphocyte precursors

The relationship between the compatibility in minor histocompatibility HA-1 antigen and the activation of helper (IL-2 producing) T lymphocyte precursors in vitro was studied in the group of 17 HLA-A2 positive HLA identical siblings. Although the number of pairs studied is still small, no correlation has been found between HA-1 compatibility and helper T lymphocyte precursors activation. The results presented here could suggest the possibility that the HTLp assay does not have to be a relevant parameter for the detection of HA-1 mismatches in HLA identical siblings.

Rapid identification of minor histocompatibility antigen HA-1 subtypes H and R using fluorescence-labeled oligonucleotides

Donor-recipient disparitiy of the minor histocompatibility antigen HA-1 is relevant for the development of graft-versus-host disease after HLA-matched sibling allogeneic bone marrow transplantation in HLA-A*0201-positive individuals. Two different alleles of HA-1 with a single amino acid polymorphism have been identified. Here we describe a time- and cost-efficient method for HA-1 typing of genomic DNA, using site-specific hybridization probes with the LightCycler. This method was compared with standard techniques as sequencing or allele-specific polymerase chain reaction (PCR) and proved to be specific, reliable and reproducible. We conclude that HA-1-subtyping using fluorescent-labeled oligonucleotides represents a attractive method for the screening of samples before allogeneic transplantation in HLA-A*0201-positive individuals.

Genomic typing of minor histocompatibility antigen HA-1 by reference strand mediated conformation analysis (RSCA)

Disparities in minor histocompatibility antigen (mHAg) HA-1 are involved in the development of acute graft-versus-host disease (GvHD) in adult recipient after HLA-identical sibling donor hematopoietic stem cell transplantation. The mHAg HA-1 is an HLA-A*0201-restricted nonapeptide, which derives from the cleavage of a protein encoded at chromosome 19. The sequence analysis of HA-1 cDNA identified two alleles, termed HA-1H and HA-1R, which differ in only two nucleotides at 3' end of exon A, at positions 500 and 504. DNA-based methods for HA-1 typing were developed in 1998, using polymerase chain reaction with sequence-specific primers (PCR-SSP) and restriction fragment length polymorphism (PCR-RFLP). Here, we report the usefulness of reference strand mediated conformation analysis (RSCA), which was developed for mutation detection and typing of polymorphic loci, to discriminate between the two HA-1 alleles. We performed genomic typing of HA-1 locus in 203 HLA-A*0201-positive samples using RSCA and we confirmed these results by PCR-SSP. The results demonstrate the high reproducibility of this method and their strong correlation with the results obtained by PCR-SSP (99%). Only two samples showed disparity between the RSCA typing and the PCR-SSP. Direct sequencing of these samples confirmed that the correct allele assignment was that obtained by the RSCA typing. Furthermore, HA-1- RSCA-based typing provides additional information about the intronic structure of both alleles. With this approach, we describe the almost constant presence (99.2%) of a 5-bp deletion at intronic position 214-218 associated to the HA-1H allele, previously unidentified. We conclude that HA-1 genomic typing by RSCA is easy to perform and that could be used as a routine typing method.

Molecular modeling of the minor histocompatibility antigen HA-1 peptides binding to HLA-A alleles

Mismatch of the minor histocompatibility antigen HA-1 has been shown to correlate with graft-versus-host disease in HLA-matched sibling marrow transplants. The HA-1H peptide (VLHDDLLEA) that generates this response is known to be presented by HLA-A*0201. In order to understand the interaction of HA-1 peptides with other HLA-A alleles, we have used the LOOK interface to construct molecular models of both HA-1H peptide (VLHDDLLEA) and HA-1R peptide (VLRDDLLEA) binding with 103 HLA-A alleles. The results show that in addition to A*0201, 21/103 other HLA-A alleles should be able to bind HA-1H peptide but not HA-1R peptide. Based on the modeled predictions, HLA alleles can be categorised into 4 groups with respect to their interaction with HA-1 peptides: Group 1 - bind HA-1H peptide but not HA-1R peptide; Group 2 - bind HA-1R peptide but not HA-1H peptide; Group 3 - bind both HA-1H and HA-1R peptides; Group 4 - bind neither peptide. These predicted binding patterns of HA-1 peptides will be useful as an aid for defining a wider pool of HLA-A alleles in which HA-1 disparities among donor-recipient pairs can be investigated.

Correlation Between Disparity for the Minor Histocompatibility Antigen HA-1 and the Development of Acute Graft-Versus-Host Disease After Allogeneic Marrow Transplantation

Results of a previous study suggested that recipient mismatching for the minor histocompatibility antigen HA-1 is associated with acute graft-versus-host disease (GVHD) after allogeneic marrow transplantation. In that study, most patients received either cyclosporine or methotrexate for GVHD prophylaxis, and a cytotoxic T-cell clone was used to test for HA-1 disparity. To facilitate large-scale testing, we developed a method that uses genomic DNA to identify HA-1 alleles. A retrospective study was conducted to correlate HA-1 disparity and the occurrence of acute GVHD in 237 HLA-A2–positive white patients who had received a marrow or peripheral blood stem cell transplant from an HLA-identical sibling. All patients received both methotrexate and cyclosporine for GVHD prophylaxis. The presence of HLA-A*0201 was confirmed in 34 of the 36 HA-1 disparate pairs by sequencing the HLA-A locus. Grades II-IV GVHD occurred in 22 (64.7%) of these 34 patients, compared with 86 (42.8%) of the 201 patients without HA-1 disparity (odds ratio, 2.45; 95% confidence interval [CI], 1.15 to 5.23; P = .02). Recipient HA-1 disparity showed a trend for association with acute GVHD (odds ratio, 2.1; 95% CI, 0.91 to 4.68; P = .08) when a multivariable logistic regression model was used to include additional risk factors. These data are consistent with results of the previous study, suggesting an association between HA-1 disparity and risk of acute GVHD, but the strength of this association may be lower in patients who received both methotrexate and cyclosporine than in those who received methotrexate or cyclosporine alone.

Tetrameric HLA class I-minor histocompatibility antigen peptide complexes demonstrate minor histocompatibility antigen-specific cytotoxic T lymphocytes in patients with graft-versus-host disease

Graft-versus-host disease (GvHD) is a chief complication of allogeneic bone marrow transplantation. In HLA-identical bone marrow transplantation, GvHD may be induced by disparities in minor histocompatibility antigens (mHags) between the donor and the recipient, with the antigen being present in the recipient and not in the donor. Cytotoxic T lymphocytes (CTLs) specific for mHags of the recipients can be isolated from the blood of recipients with severe GvHD (ref. 3). A retrospective study demonstrated an association between mismatch for mHags HA-1, -2, -4 and -5 and the occurrence of GvHD in adult recipients of bone marrow from HLA genotypically identical donors. Tetrameric HLA-peptide complexes have been used to visualize and quantitate antigen-specific CTLs in HIV-infected individuals and during Epstein-Barr virus and lymphocytic choriomeningitis virus infections. Here we show the direct ex vivo visualization of mHag-specific CTLs during GvHD using tetrameric HLA-class and I-mHag HA-1 and HY peptide complexes. In the peripheral blood of 17 HA-1 or HY mismatched marrow recipients, HA-1- and HY-specific CTLs were detected as early as 14 days after bone marrow transplantation. The tetrameric complexes demonstrated a significant increase in HA-1- and HY-specific CTLs during acute and chronic GvHD, which decreased after successful GvHD treatment. HLA class I-mHag peptide tetramers may serve as clinical tools for the diagnosis and monitoring of GvHD patients.