HLA-DPB1 Mismatches Research Articles

HLA-DPB1 Mismatch and Chronic Graft-Versus-Host Disease Are Favorable Independent Risk Factor for Graft-Versus-Leukemia Effect in Leukemia Patients Transplanted Marrow from HLA-A, -B, -C, -DRB1 and -DQB1 Matched Unrelated Donor

HLA-DPB1 Mismatch and Chronic Graft-Versus-Host Disease Are Favorable Independent Risk Factor for Graft-Versus-Leukemia Effect in Leukemia Patients Transplanted Marrow from HLA-A, -B, -C, -DRB1 and -DQB1 Matched Unrelated Donor

Allogeneic Transplantation: When is a Mismatch Better than a Match?

An accepted fact in allogeneic transplantation from unrelated donors, supported by multiple publications, including large numbers of transplantation patients, is that matching for human leukocyte antigen (HLA) is critical to ensure the best outcomes for patients. The current gold standard is an unrelated donor matched for 10/10 (or 8/8) HLA alleles (at HLA-A, -B, -C, -DRB1 þ/ DQB1). Graft-versus-host disease (GVHD) is increased in the HLA-mismatched setting, and overall survival becomes significantlyworse as the number of mismatched alleles at these loci increases [1,2]. Interestingly, data now suggest that an HLA mismatch may actually be tolerated, or even beneficial, in some transplant settings. This has been shown inparticular forHLA-DPB1where mismatching for this locus at allelic level reduces the risk of disease relapse, both inaTcelledepleted [3]andaTcellereplete setting [4]. Even more provocative is the observation, based on functional studies, that beingmatched ormismatched for DPB1 T cell epitope (TCE) groups provides a better prediction of transplant outcomes, including overall survival, than does consideration of DPB1 allele level matching alone [5]. It is well demonstrated in both the in vivo and in vitro setting that HLA-DPB1 is able to elicit an allogeneic response in a specific manner. This was originally shown in the setting of GVHD [6] but has since also been shown in the setting of graft rejection (using the TCE model) [7]. Proof of principle that HLA-DPB1 mismatches could be a specific target of the graft-versus-leukemia (GVL) effect was shown by Ibisch et al., who demonstrated that primary leukemia blasts both expressed variable levels of DPB1 on the cells surface and could be killed by DPB1-specific T cells [8]. Taking this work into the clinic, Dr. Falkenburg’s group [9] previously showed they could detect polyclonal HLA-DPB1 specific T cells in a patient with B-cell chronic lymphocytic leukaemia who responded to donor lymphocyte infusion (DLI) (from a DPB1mismatched donor) [9]. In this issue, Rutten and colleagues extend these findings in 24 patients undergoing transplantation from a 10/10 HLAmatched, DPB1-mismatched unrelated donor [10]. The authors develop an elegant assay for quantifying HLADPB1especific responses by measuring CD137þ CD4þ T cells

Patient HLA-DP–Specific CD4+ T Cells from HLA-DPB1–Mismatched Donor Lymphocyte Infusion Can Induce Graft-versus-Leukemia Reactivity in the Presence or Absence of Graft-versus-Host Disease

Clinical studies have demonstrated that HLA-DPB1–mismatched allogeneic stem cell transplantation (allo-SCT) is associated with a decreased risk of disease relapse and an increased risk of graft-versus-host disease (GVHD) compared with HLA-DPB1–matched SCT. In T cell–depleted allo-SCT, mismatching of HLA-DPB1 was not associated with an increased risk of severe GVHD, but a significant decreased risk of disease relapse was still observed. To investigate whether patient HLA-DP–specific CD4+ T cell responses were frequently induced after T cell–depleted HLA-DPB1–mismatched allo-SCT and donor lymphocyte infusion (DLI), we developed a method to screen for the presence of HLA-DP–specific CD4+ T cells using CD137 as an activation marker and analyzed 24 patient–donor combinations. The patients suffered from various B cell malignancies, multiple myeloma, and myeloid leukemias. Patient HLA-DP–specific CD4+ T cells were detected after DLI in 13 of 18 patients who exhibited a clinical response to DLI, compared with only 1 of 6 patients without a clinical response to DLI. Eight patients developed significant GVHD. These data show that patient HLA-DP–specific CD4+ T cells frequently occur after HLA-DPB1–mismatched T cell–depleted allo-SCT and DLI, and are associated with graft-versus-leukemia reactivity both in the presence and absence of GVHD.

Investigation of the impact of HLA-DPB1 matching status in 10/10 HLA matched unrelated hematopoietic stem cell transplantation: Results of a French single center study

The impact of HLA-DPB1 mismatches after unrelated hematopoietic stem cell transplantation (HSCT) remains controversial. We retrospectively analyzed the impact of permissive/non-permissive HLA-DPB1 mismatches on the outcome of 141 patients who underwent 10/10 HLA allelic-matched unrelated HSCT. Each pair was classified according to the 3 (TCE3) and 4-group (TCE4) algorithm based on DPB1 alleles immunogenicity. Outcome analysis revealed that TCE3 and TCE4 non-permissive HLA-DPB1 disparities were not associated with worsened overall survival, relapse risk neither risk of acute GvHD. Overall, this single center retrospective study does not confirm the adverse prognostic of non-permissive HLA-DPB1 mismatches.

Effect of T-cell-epitope matching at HLA-DPB1 in recipients of unrelated-donor haemopoietic-cell transplantation: a retrospective study

The risks after unrelated-donor haemopoietic-cell transplantation with matched HLA-A, HLA-B, HLA-C, HLA-DRB1, HLA-DQB1 alleles between donor and recipient (10/10 matched) can be decreased by selection of unrelated donors who also match for HLA-DPB1; however, such donors are difficult to find. Classification of HLA-DPB1 mismatches based on T-cell-epitope groups could identify mismatches that might be tolerated (permissive) and those that would increase risks (non-permissive) after transplantation. We did a retrospective study to compare outcomes between permissive and non-permissive HLA-DPB1 mismatches in unrelated-donor haemopoietic-cell transplantation. HLA and clinical data for unrelated-donor [corrected] transplantations submitted to the International Histocompatibility Working Group in haemopoietic-cell transplantation were analysed retrospectively. HLA-DPB1 T-cell-epitope groups were assigned according to a functional algorithm based on alloreactive T-cell crossreactivity patterns. Recipients and unrelated donors matching status were classified as HLA-DPB1 match, non-permissive HLA-DPB1 mismatch (those with mismatched T-cell-epitope groups), or permissive HLA-DPB1 mismatch (those with matched T-cell-epitope groups). The clinical outcomes assessed were overall mortality, non-relapse mortality, relapse, and severe (grade 3-4) acute graft-versus-host disease (aGvHD). Of 8539 transplantations, 5428 (64%) were matched for ten of ten HLA alleles (HLA 10/10 matched) and 3111 (36%) for nine of ten alleles (HLA 9/10 matched). Of the group overall, 1719 (20%) were HLA-DPB1 matches, 2670 (31%) non-permissive HLA-DPB1 mismatches, and 4150 (49%) permissive HLA-DPB1 mismatches. In HLA 10/10-matched transplantations, non-permissive mismatches were associated with a significantly increased risk of overall mortality (hazard ratio [HR] 1·15, 95% CI 1·05-1·25; p=0·002), non-relapse mortality (1·28, 1·14-1·42; p<0·0001), and severe aGvHD (odds ratio [OR] 1·31, 95% CI 1·11-1·54; p=0·001), but not relapse (HR 0·89, 95% CI 0·77-1·02; p=0·10), compared with permissive mismatches. There were significant differences between permissive HLA-DPB1 mismatches and HLA-DPB1 matches in terms of non-relapse mortality (0·86, 0·75-0·98; p=0·03) and relapse (1·34, 1·17-1·54; p<0·0001), but not for overall mortality (0·96, 0·87-1·06; p=0·40) or aGvHD (OR 0·84, 95% CI 0·69-1·03; p=0·09). In the HLA 9/10 matched population, non-permissive HLA-DPB1 mismatches also increased the risk of overall mortality (HR 1·10, 95% CI 1·00-1·22; p=0·06), non-relapse mortality (1·19, 1·05-1·36; p=0·007), and severe aGvHD (OR 1·37, 95% CI 1·13-1·66; p=0·002) compared with permissive mismatches, but the risk of relapse was the same in both groups (HR 0·93, 95% CI 0·78-1·11; p=0·44). Outcomes for HLA 10/10-matched transplantations with non-permissive HLA-DPB1 mismatches did not differ substantially from those for HLA 9/10-matched transplantations with permissive HLA-DPB1 mismatches or HLA-DPB1 matches. T-cell-epitope matching defines permissive and non-permissive HLA-DPB1 mismatches. Avoidance of an unrelated donor with a non-permissive T-cell-epitope mismatch at HLA-DPB1 might provide a practical clinical strategy for lowering the risks of mortality after unrelated-donor haemopoietic-cell transplantation. National Institutes of Health; Associazione Italiana per la Ricerca sul Cancro; Telethon Foundation; Italian Ministry of Health; Cariplo Foundation; National Cancer Institute; National Heart, Lung and Blood Institute; National Institute of Allergy and Infectious Diseases; Office of Naval Research; IRGHET Paris; Swedish Cancer Society; Children's Cancer Foundation; Swedish Research Council; Cancer Society in Stockholm; Karolinska Institutet; and Leukemia and Lymphoma Society.

Acceptable HLA-mismatching in unrelated donor bone marrow transplantation for patients with acquired severe aplastic anemia

AbstractWe retrospectively analyzed the effect of HLA mismatching (HLA-A, -B, -C, -DRB1, -DQB1) with molecular typing on transplantation outcome for 301 patients with acquired severe aplastic anemia (SAA) who received an unrelated BM transplant through the Japan Marrow Donor Program. Additional effect of HLA-DPB1 mismatching was analyzed for 10 of 10 or 9 of 10 HLA allele-matched pairs (n = 169). Of the 301 recipient/donor pairs, 101 (33.6%) were completely matched at 10 of 10 alleles, 69 (23%) were mismatched at 1 allele, and 131 (43.5%) were mismatched at ≥ 2 alleles. Subjects were classified into 5 subgroups: complete match group (group I); single-allele mismatch group (groups II and III); multiple alleles restricted to HLA-C, -DRB1, and -DQB1 mismatch group (group IV); and others (group V). Multivariate analysis indicated that only HLA disparity of group V was a significant risk factor for poor survival and grade II-IV acute GVHD. HLA-DPB1 mismatching was not associated with any clinical outcome. We recommend the use of an HLA 10 of 10 allele-matched unrelated donor. However, if such a donor is not available, any single-allele or multiple-allele (HLA-C, -DRB1, -DQB1) mismatched donor is acceptable as an unrelated donor for patients with severe aplastic anemia.

The T-Cell Epitope (TCE) Algorithm for Classifying HLA-DPB1 Mismatches Does Not Predict Clinical Outcomes in HSCT

A number of reports suggested the relevance of HLA-DPB1 matching for the outcomes of allogeneic hematopoietic stem cell transplantation (HSCT). An algorithm for determining DPB1 mismatch permissiveness based on T-Cell Epitopes (TCE) has been proposed (Zino et al, Blood 2004). According to this algorithm, all DPB1 alleles are categorized in 3 (TCE3) or 4 (TCE4) groups based on antigenicity. Accordingly DPB1 mismatches are classified as permissive; non-permissive in GvHD; or non-permissive in HvG direction.

Permissive HLA-DPB1 Mismatching Compared to a Non-Permissive Mismatching Significantly Improves Overall Survival Following Allogeneic Transplantation In Patients with Both 10/10 and 9/10 Matched Unrelated Donors

AbstractAbstract 227It is well established that the use of a donor matched for 9–10/10 alleles at HLA-A,-B,-C,-DRB1,-DQB1 significantly improves overall survival (OS) after unrelated donor (UD) haematopoietic stem cell transplantation (HSCT). Whilst the matching status for HLA-DPB1 alleles has been shown to influence transplant complications (relapse and graft-versus-host disease (GVHD), its impact on survival has not been well defined. The current unmet need in clinical practice is an approach to stratify selection criteria when a clinician is confronted with the choice between several 10/10 or 9/10 matched unrelated donors.There is now considerable interest in exploring different types of matching criteria to define permissive HLA-DPB1 mismatches which may be associated with an improved outcome. We have previously shown that HLA-DPB1 permissiveness can be functionally defined by the characterization of shared T cell epitopes (TCE) recognized by alloreactive T cells. In this model, allelic HLA mismatches are classified as permissive if they do not involve TCE disparities, and as non-permissive if they do. Using this concept, we developed two overlapping algorithms of permissivity for allelic HLA-DPB1 mismatches, on the basis of 3 (TCE3) or 4 (TCE4) groups of DPB1 alleles encoding immunogenic TCE. Data from relatively small prospective studies has shown a worse outcome to be associated with non-permissive DPB1 TCE disparities.Here, we present outcomes in 9123 UD-HSCT pairs, collected through the International Histocompatibility Working Group (IHWG). The cohort was comprised of 5809 10/10 matched transplant pairs and 3314 9/10 matched pairs. Within the 10/10 and 9/10 matched pairs three groups of patients were identified: 1. Zero DPB1 mismatches (i.e. allele matched), 2. Permissive DPB1 mismatch, 3. Non-permissive DPB1 mismatch. The model was adjusted for disease severity, source of stem cells, conditioning regimen, use of T-cell depletion, patient/donor gender and patient age.In line with DPB1 allele frequencies in worldwide populations, the number of transplants scored as permissive was higher for TCE3 (4398/7270 [60.4%]) than for TCE4 (2577/7270 [35.4%]). Using the DPB1 permissive mismatch transplants as the reference group (either 10/10 or 9/10 matched), we showed that DPB1 allelic matches resulted in similar survivals to DPB1 permissive mismatches, both in the 10/10 (HR 0.96, p=0.498 for TCE3 and HR 0.99, p=0.85 for TCE4) and the 9/10 setting (HR 0.97, p=0.70 for TCE3 and HR 0.99, p=0.96 for TCE4).In contrast, survival was significantly worse in the presence of a non-permissive TCE3 or TCE4 mismatch, both in the 10/10 (HR 1.15, p=0.0005 for TCE3 and HR 1.13, p=0.0035 for TCE4) and in the 9/10 matched setting (HR 1.13, p=0.0140 for TCE3 and HR 1.11, p=0.0448 for TCE4). The survival detriment appeared to be due to a significantly increased non-relapse mortality (TCE3: 10/10 HR 1.27, p<0.001 and 9/10 HR 1.21, p=0.0001; TCE4: 10/10 HR 1.24, p<0.001 and 9/10 HR 1.13, p=0.0514), as well as an increase in grades II-IV acute GVHD (TCE3: 10/10 HR 1.17, p<0.001 and 9/10 HR 1.29, p<0.001; TCE4: 10/10 HR 1.12, p=0.0035 and 9/10 HR 1.19, p<0.0001). There was no significant difference in disease relapse between permissive and non-permissive mismatched pairs. Finally, using the 10/10 DPB1 permissive mismatched group as a reference, we found survival to be similar for 10/10 DPB1 non-permissive (HR 1.15) and 9/10 DPB1 permissive (HR 1.20) or DPB1 allele matched (HR 1.17) transplants.In conclusion, our results suggest that extending donor selection to include HLA-DPB1 both allelic and functional TCE matching may result in better prediction of survival for patients. These findings provide an attractive new algorithm to stratify donor choice when several well-matched UD are identified. Disclosures:No relevant conflicts of interest to declare.

HLA-DPB1 Mismatching Results in the Generation of a Full Repertoire of HLA-DPB1-Specific CD4 + T Cell Responses Showing Immunogenicity of all HLA-DPB1 Alleles

Clinical studies have indicated that HLA-DPB1 functions as a classical transplantation antigen in allogeneic stem cell transplantation. Mismatching for HLA-DPB1 was associated with an increased risk of graft-versus-host disease (GVHD), but also a decreased risk of disease relapse. However, specific HLA-DPB1 mismatches were associated with poor clinical outcome. It was suggested that this unfavorable effect was caused by a difference in immunogenicity between HLA-DPB1 alleles. To analyze whether immunogenicity of HLA-DPB1 mismatches could be predicted based on the presence or absence of specific amino acid sequences we developed a model to generate allo-HLA-DPB1 responses in vitro. We tested in total 48 different stimulator/responder combinations by stimulating CD4(+) T cells from 5 HLA-DPB1 homozygous individuals with the same antigen-presenting cells transduced with different allo-HLA-DPB1 molecules. HLA-DPB1 molecules used for stimulation comprised 76% to 99% of HLA-DPB1 molecules present in different ethnic populations. We show that all HLA-DPB1 mismatches as defined by allele typing resulted in high-frequency immune responses. Furthermore, we show that crossrecognition of different HLA-DPB1 molecules is a broadly observed phenomenon. We confirm previously described patterns in crossrecognition, and demonstrate that a high degree in similarity between HLA-DPB1 molecules is predictive for crossrecognition, but not for immunogenicity.

HLA mismatch combinations associated with decreased risk of relapse: implications for the molecular mechanism

AbstractThe finding that the risk of relapse in hematologic malignancy decreases after allogeneic hematopoietic stem cell transplantation (HSCT) has lead to the concept of a graft-versus-leukemia (GVL) effect. However, this beneficial effect is considered to be frequently offset by graft-versus-host disease (GVHD). Thus, improving HSCT outcomes by separating GVL from GVHD is a key clinical issue. This cohort study registered 4643 patients with hematologic malignancies who received transplants from unrelated donors. Six major human leukocyte antigen (HLA) loci were retrospectively genotyped. We identified 4 HLA-Cw and 6 HLA-DPB1 mismatch combinations responsible for a decreased risk of relapse; of these, 8 of 10 combinations were different from those responsible for severe acute GVHD, including all 6 of the HLA-DPB1 combinations. Pairs with these combinations of HLA-DPB1 were associated with a significantly better overall survival than were completely matched pairs. Moreover, several amino acid substitutions on specific positions responsible for a decreased risk of relapse were identified in HLA-Cw, but not in HLA-DPB1. These findings might be crucial to elucidating the mechanism of the decreased risk of relapse on the basis of HLA molecule. Donor selection made in consideration of these results might allow the separation of GVL from acute GVHD, especially in HLA-DPB1 mismatch combinations.

HLA-DPB1 Mismatching Results in the Generation of a Full Repertoire of HLA-DPB1 Specific T Cell Responses Showing Immunogenicity of All HLA-DPB1 Alleles

In unrelated donor hematopoietic stem cell transplantation (URD-SCT) patients are preferably transplanted with stem cells from a fully HLA matched donor, usually defined as identical for HLA-class I, -DR and -DQ. Since HLA-DPB1 is often not taken into consideration in donor selection, 80–90% of URD-SCTs are mismatched for HLA-DPB1. The role of HLA-DPB1 as transplantation antigen has been unclear, since clinical reports on the impact of matching for HLA-DPB1 on transplant outcome showed conflicting results. HLA-DPB1 mismatching has been associated with an increased risk of graft versus host disease (GVHD). However, we recently demonstrated that HLA-DPB1 specific T cells can mediate a potent graft versus leukemia effect without inducing GVHD. It has been suggested that the controversial effects of matching for HLA-DPB1 in URD-SCT could partly be explained by the assumption that not all HLA-DPB1 differences are immunogenic. This theory was based on the cross-reactive recognition of two HLA-DPB1* 09 specific T cell clones that recognized other HLA-DPB1 alleles sharing amino acids (aa) in position 8–11 of HLA-DPB1 (Zino et al, blood 2004). It was hypothesized that there would be no induction of T cell responses between individuals expressing HLA-DPB1 molecules sharing this aa sequence. This was translated into a classification of permissive and non-permissive HLA-DPB1 mismatches in order to allow a broader donor selection. To investigate whether cross-reactive recognition of other HLA-DPB1 molecules by our previously generated HLA-DPB1*02 or *03 specific CD4+ T cell clones depended on the presence of specific aa sequences we tested recognition of a panel of 14 EBV-LCL expressing 9 different HLA-DPB1 molecules. All HLA-DPB1*02 as well as all *03 specific T cell clones showed cross-reactivity with other HLA-DPB1 alleles and each T cell clone exhibited its own pattern of cross-reactivity. Two HLA-DPB1*0201 specific T cell clones with different TCR-Vβ showed also recognition of EBV-LCL expressing HLA-DPB1*1001 and *1701 or HLA-DPB1*1001, *0901 and *1601 respectively. Five HLA-DPB1*03 reactive T cells clones with different TCR-Vβ showed differential cross-recognition of EBV-LCL expressing HLA-DPB1*0101, *0601, *1101, *1301 and *1401. To identify immunogenic differences the aa sequences of the HLA-DPB1 molecules recognized by the various T cell clones were compared. The HLA-DPB1 molecules recognized by the HLA-DPB1*02 specific T cell clones shared an aa substitution at position 69 compared to the responder cell. However, HLA-DPB1*0601,*0901 and *1901 with the same substitution were not recognized by both T cell clones. This phenomenon was also observed for the HLA-DPB1*03 specific T cell clones, indicating that the cross-reactive recognition of HLA-DPB1 could not be predicted by aa sequences. Next, we analyzed the immunogenicity of various HLA-DPB1 alleles in different stimulator/responder combinations to verify the classification of permissive and non-permissive mismatches. We developed a model to generate allo-HLA-DP responses by transducing HLA-class II negative HELA cells with various HLA-DP molecules and used these cells to stimulate purified CD4+ T cells from HLA-DPB1 homozygous donors. HELA cells transduced with HLA-DPB1*0101, *0201, *0301, *0401, *0402, *0501, *0601, *0901, *1101, *1301, *1401 or *1701 were used as stimulator cells. Responder CD4+ T cells were typed HLA-DPB1* 0201, *0301, *0401 or *0402. 14 days after stimulation, CD4+ T cells were tested for recognition of the stimulator cells and of HELA cells transduced with the responder HLA-DPB1 molecule as a negative control. For these 4 responders, stimulation with 12 different HLA-DP transduced HELA cell lines resulted in specific IFN-γ production in response to the stimulator cells in 47 out of 48 stimulations. 28 CD4+ T cell lines also showed cross-reactive recognition of HELA cells transduced with at least one other HLA-DPB1 molecule. In conclusion, we showed that cross-reactive recognition of various HLA-DPB1 molecules by HLA-DPB1 specific T cells is a common observation. However, we demonstrated that cross-reactivity between HLA-DPB1 molecules by allo-HLA-DPB1 specific T cells does not exclude the generation of immune response between individuals expressing these HLA-DPB1 molecules. By generating multiple allo-HLA-DP specific T cell lines, we showed that all HLA-DPB1 mismatch combinations are immunogenic.

Donor-Recipient Mismatches in MHC Class I Chain-Related Gene a (MICA) in Unrelated Donor (UD) Transplantation

MICA is a highly polymorphic locus located in the Class III region of the HLA system in the short arm of chromosome 6. The products of MICA can elicit humoral allo-recognition and are the ligands of the NKG2-D receptors of natural killer cells. MICA is involved in chronic and possibly acute graft rejection in kidney transplantation. The impact of mismatches in MICA has not been examined systematically in bone marrow transplantation. We hypothesized that donor-recipient MICA mismatches may influence graft-versus-host disease (GVHD) and relapse rates after UD hematopoietic stem cell transplantation (HSCT), and tested this hypothesis in a cohort comprised of all patients with myeloid leukemias transplanted in our institution from January, 2002 to December, 2007 (n=238).Methods: Typing of each of the classical human leukocyte antigen (HLA) and MICA loci was performed by amplification with locus-specific primers of genomic DNA by PCR followed by nucleotide sequencing. For the assignment of MICA alleles, the polymorphisms in exons 2, 3, 4, and 5 were evaluated. Matching grade is described in the GVH direction. Outcomes were acute (a) GVHD incidence, and aGVHD-free survival (time dependent variable, with development of aGVHD as the event), and relapse-free survival (RFS), both estimated by the Kaplan Meier method. Cox proportional hazards regression model was used to estimate the influence of HLA match degree, patient, disease, and transplant-related characteristics on outcomes. Median age was 50 years (range, 18–74; 24% over age 59). Diagnosis were AML/high-risk MDS in 82% (n=195) and CML in 18% (n=43). 42% (n=100) of the patients were in remission (CR) at HSCT. Preparative regimens were ablative in 59% (n=141), and contained ATG, fludarabine and IV busulfan in respectively 96%, 90% and 70% of the HSCT. GVHD prophylaxis was tacrolimus and mini-methotrexate-based in all HSCT. Stem cell source was bone marrow (BM) in 72% (n=172) and peripheral blood (PB) in 28% (n=66) of HSCT. 78 patients have relapsed (34%) and 133 have died (56%).Results. 169 pairs were matched in HLA A, B, C, DRB1, and DQB1 (10/10; 71%); 69 (29%) were <10/10 matches, of which 60 were 9/10 (78% of the mismatches were in HLA class I). One or two HLA-DPB1 mismatches were present in 48% and 25% of the patients, respectively. MICA one or two mismatches were present in 22 pairs (9%). Grade (gd) II–IV and III–IV aGVHD rates for patients with MICA mismatches were 80% and 30%, respectively, versus 40% and 14% for those with no MICA mismatches. Effect of MICA on aGVHD was similar among 10/10 and <10/10 patients. RFS at 52 weeks post HSCT was 0.58 (95%CI 0.5–0.66) versus 0.77 (95%CI 0.59–1) for patients without and with MICA mismatches (P=0.5). Multivariate models are shown in the table.Conclusion: MICA mismatches independently increased the incidence of grade II–IV aGVHD.Multivariate Models for grade II-IV acute GVHD and relapse-free survival (RFS)VariableIncidenceUnivariate P valueMultivariate P, HR and 95% CIGrade II-IV aGVHDFludarabine-based regimen(yes vs no)39% vs 72%P=0.00090.02; HR 0.51 (0.29–0.9)DPB1 mismatches (0/1 vs 2)38% vs 52%P=0.060.03; HR 0.59 (0.37–0.94)Ablative conditioning (no vs yes)31% vs 48%P=0.0010.05; HR 0.65 (0.43–0.99)MICA mismatches (yes vs no)80% vs 38%P=0.00020.002; HR 2.33 (1.37–3.98)RFSRate at 52 weeks95%CI Univariate PMultivariate P, HR and 95% CIDPB1 (0 vs 1 vs 2)0.54(0.42, 0.68)P=0.090.03; HR 1.65 (1.051–2.6)0.55(0.45, 0.67)0.7(0.58, 0.84)CR at HSCT (yes vs no)0.78(0.69, 0.87)P<0.0001<0.0001; HR 0.308 (0.18–0.52)0.44(0.36, 0.55)(P and HR for aGVHD-free survival) HR: hazard ratio; CI: confidence interval

The importance of HLA-DPB1 in unrelated donor hematopoietic cell transplantation

Hematopoietic cell transplantation (HCT) from an HLA-A, HLA-B, HLA-C, HLA-DRB1, and HLA-DQB1 allele-matched unrelated donor is a well-recognized life-saving treatment modality for patients with hematologic disorders. The morbidity and mortality from clinically significant acute graft-versus-host disease (aGVHD) remains a limitation. The extent to which transplantation outcome may be improved with donor matching for HLA-DP is not well defined. The risks of aGVHD, relapse, and mortality associated with HLA-DPB1 allele mismatching were determined in 5929 patients who received a myeloablative HCT from an HLA-A-, HLA-B-, HLA-C-, HLA-DRB1-, and HLA-DQB1-matched or -mismatched donor. There was a statistically significantly higher risk of both grades 2 to 4 aGVHD (odds ratio [OR] = 1.33; P < .001) and grades 3 to 4 aGVHD (OR = 1.26; P < .001) after HCT from an HLA-DPB1-mismatched donor compared with a matched donor. The increased risk of aGVHD was accompanied by a statistically significantly decrease in disease relapse (hazard ratio [HR] = 0.82; P = .01). HLA-DPB1 functions as a classical transplantation antigen. The increased risk of GVHD associated with HLA-DPB1 mismatching is accompanied by a lower risk of relapse. Knowledge of the DPB1 matching status prior to transplantation will aid in more precise risk stratification for the individual patient.

Identification of HLA Allele Mismatch Combinations and Amino Acid Substitution Positions Associated with GVL Effect after Unrelated HSCT: Analysis from the Japan Marrow Donor Program.

Graft-versus-leukemia (GVL) effect is considered to reduce relapse rate due to eradication of residual leukemia cells after allogeneic hematopoietic stem cell transplantation (HSCT). Segregation it from graft-versus-host disease (GVHD) has been main issue clinically. We recently clarified 16 high-risk HLA mismatch combinations and eight high-risk specific amino acid substitution positions for severe acute GVHD in six HLA loci. In the current study, we clarified HLA allele mismatch combinations and amino acid substitution positions associated with GVL effect. Consecutive 4643 patients transplanted for hematological malignancy (ALL, AML, CML, MDS, MM and ML) with T cell replete marrow from a serologically HLA-A, -B and -DR antigen-matched donor through Japan Marrow Donor Program were registered in this cohort study. All HLA-A, -B, -C, -DRB1, -DQB1 and -DPB1 alleles were retrospectively typed. The effect of HLA locus mismatch in allele level, the HLA allele mismatch combinations in HLA six loci and amino acid substitution positions on reduced relapse rate was analyzed using a multivariable competing risk regression model. As results (1) Mismatches of HLA-C (Odds ratio (OR)=0.69; p<0.0001) and HLA-DPB1 (OR=0.78; p<0.0001) were strongly reduced leukemia relapse, and HLA-A (OR=0.99; p=0.9), HLA-B (OR=0.98; p=0.91), HLA-DRB1 (OR=0.93; p=0.54) and HLA-DQB1 (OR=1.06; p=0.54) were not. (2) Total 10 HLA mismatch combinations were significantly associated with GVL effect; four in HLA-C allele (donor Cw*0303- patient Cw*1502 (n=25) OR=0.23, Cw*0102-Cw*1402 (n=16) OR=0, Cw*0801-Cw*0102 (n=10) OR=0 and Cw*1402-Cw*0304 (n=23) OR=0), six in HLA-DPB1 allele (DP*0402-DP*0201 (n=66) OR=0.41,?DP*0501-DP*0201 (n=351) OR=0.7,?DP*0501-DP*0401 (n=53) OR=0.45,?DP*0501-DP*0402?(n=121) OR=0.59, DP*0901-DP*0201 (n=50) OR=0.38 and DP*1301-DP*0201 (n=21) OR=0), but none in HLA-A, -B, -DRB1 and -DQB1 allele. Except two of four combinations in HLA-C, the other two in HLA-C and all six in HLA-DPB1 were different from high-risk one for severe acute GVHD. (3) Specific amino acid substitution at positions 9, 99, 156 in HLA-C molecule was elucidated as significant factors responsible for GVL effect and one of three was different from substitutions responsible for severe acute GVHD. As for HLA-DPB1, no significant association between the positions of specific amino acid substitution and GVL were found. In conclusion, large scale comprehensive analysis made it possible to identify 4 HLA-C and 6 HLA-DPB1 mismatch combinations responsible for GVL effects, some of which are different from one responsible for acute GVHD. Responsible amino acid substitutions on specific position were also elucidated in HLA-C, but not in HLA-DPB1. These findings suggest that donor selection according to these results could segregate GVL from acute GVHD, therefore these strategies might be beneficial for the selection of suitable donor for HSCT. And that, we speculate that the molecular base of GVL caused by the HLA-DPB1 mismatch might be different from that in HLA-C.

Effects of HLA Allele and Killer Immunoglobulin-Like Receptor Ligand Matching on Clinical Outcome in Leukemia Patients Undergoing Transplantation With T-cell–Replete Marrow From an Unrelated Donor

The responsible human leukocyte antigen (HLA) locus and the role of killer immunoglobulin-like receptor (KIR) ligand matching on transplantation outcome were simultaneously identified by multivariate analysis in 1790 patients with leukemia who underwent transplantation with T-cell–replete marrow from an unrelated donor (UR-BMT) through the Japan Marrow Donor Program. The graft-versus-leukemia (GVL) effect depended on leukemia cell type. HLA-C mismatch reduced the relapse rate in acute lymphoblastic leukemia (ALL) (hazard ratio [HR] = 0.47; P = .003), and HLA-DPB1 mismatch reduced it in chronic myeloid leukemia (CML) (HR = 0.35; P < .001). In contrast, KIR2DL ligand mismatch in the graft-versus-host (GVH) direction (KIR-L-MM-G) increased in ALL (HR = 2.55; P = .017). An increased rejection rate was observed in KIR2DL ligand mismatch in the host-versus-graft direction (HR = 4.39; P = .012). Acute GVH disease (GVHD) was increased not only in the mismatch of HLA-A, -B, -C, and -DPB1, but also in KIR-L-MM-G. As a whole, the mismatch of HLA-A, -B, and -DQB1 locus and KIR-L-MM-G resulted in increased mortality. In conclusion, not only the mismatch of HLA-C and -DPB1, but also KIR-L-MM-G affected leukemia relapse, which should be considered based on leukemia cell type. Furthermore, KIR-L-MM induced adverse effects on acute GVHD (aGVHD) and rejection, and brought no survival benefits to patients with T-cell–replete UR-BMT.

Identification of Non-Permissive HLA Allele Mismatch Combinations and Amino Acid Substitution Responsible for Acute Graft-Versus-Host Disease in Unrelated Allogeneic Bone Marrow Transplantation.

Background: In the allogenic hematopoietic stem cell transplantation from unrelated donors (UR-HSCT), an effect of HLA locus mismatch in allele level on clinical outcome has been clarified. However, the effect of each HLA allele mismatch combinations is little known, and its molecular mechanism to induce acute graft versus host disease (aGVHD) remained to be elucidated.Methods: Consecutive 4866 patients transplanted with T cell replete marrow from a serologically HLA-A, -B and -DR antigen-matched donor through Japan Marrow Donor Program were registered in this cohort study. All HLA-A, -B, -C, -DRB1, -DQB1 and -DPB1 alleles were retrospectively typed in 2171 pairs, and partly in the other pairs. The impact of the HLA allele mismatch combinations in HLA six loci and amino acid substitution positions in HLA-C and HLA-DPB1 locus on aGVHD and survival was analyzed using a multivariable Cox regression model.Results: Significant high-risk HLA allele mismatch combinations compared with match for severe aGVHD were identified; four in HLA-A allele (donor A*0206- patient A*0201 (n=108) hazard ratio (HR): 1.77, A*0206-A*0207 (n=20) : 3.24, A*2601-A*2603 (n=32): 1.96, A*2602-A*2601 (n=24): 2.18), six in HLA-B (B*1507-B*1501 (n=14): 2.95, B*4002-B*4003 (n=14): 2.44, B*4002-B*4006 (n=85): 1.69, B*4003-B*4006 (n=7): 3.85, B*4006-B*4002 (n=60): 1.62, B*4403-B*4402 (n=4) : 5.78), 11 in HLA-C, six in HLA-DRB1, zero in HLA-DQB1 and two in HLA-DPB1. Amino acid substitutions of position 80 of HLA-C at which donor had Asp80 and patient Lys80 (Asp80-Lys80) and Ser77-Asp77 were first elucidated as significant risk factors for severe aGVHD. These two amino acid substitutions were completely linked, and HR for severe aGVHD was 1.49 (1.01–2.21). As position 80 is ligand for NK cell receptor KIR2DL as a result, further analysis was performed in the KIR2DL ligand match in the GVH vector population. Notably, particular amino acid substitution at positions 95, 156 and 163 of HLA-C was a significant risk factor for severe aGVHD. HR of Leu95-Ile95, Arg156-Leu156, Leu156-Trp156, Trp156-Leu156 and Thr163-Leu163 substitutions were 1.74 (95%CI: 1.06–2.86), 2.10 (1.16–3.81), 5.22 (1.65–16.4), 4.64 (1.04–20.7) and 1.82 (1.11–2.99), respectively. The amplitude of hydropathy scales were 0.7, 8.3, 4.7, 4.7 and 4.7, respectively. Amino acid substitutions of any other positions of HLA-C were not significant risk factors. When analyzing the location of amino acid substitution in HLA-C, residues located in the T-cell receptor contact have marginal impact on severe aGVHD (HR: 1.45 trend P=0.096), and no other locations were significant. In HLA-DPB1 mismatch combinations, there was no obvious tendency to associate the positons of amino acid substitutions with severe aGVHD and grades 2–4 aGVHD.Conclusion: These findings provide evidences to elucidate the mechanism of aGVHD on the base of HLA molecule. Furthermore, the identification of non-permissive and possible permissive mismatch would be beneficial for the selection of suitable donor and international donor exchange for UR-HSCT.

Hla-DPB1 mismatch in HLA-A-B-DRB1 identical sibling donor stem cell transplantation and acute graft-versus-host disease.

The role of human leukocyte antigen (HLA)-DPB1 as a transplantation antigen is controversial. A higher incidence of acute graft-versus-host disease (aGVHD) has been described after unrelated donor bone marrow transplant when both HLA-DPB1 alleles were mismatched. We investigated the impact of a single HLA-DPB1 mismatch after HLA-A-B-DRB1 identical sibling donor transplantation on aGVHD. We analyzed 627 adult patient-donor pairs and identified 30 pairs without HLA-DPB1 identity (4.78%). In 17 cases, the patient had an allele that was not shared by the donor. The cumulative incidence of grades II-IV aGVHD was higher in the HLA-DPB1 mismatched group (66.7% vs. 35.7%, p=0.012). The HLA-DPB1 mismatch was identified by multivariate analysis as an independent risk factor for aGVHD (p=0.020, RR=2.68, 95% CI: 1.73-3.62). HLA-DPB1 can mediate alloreactive responses. A single HLA-DPB1 mismatch increases the risk of aGVHD after sibling donor stem cell transplantation.

A new epitope-based HLA-DPB matching approach for cadaver kidney retransplants.

Several years ago a significant impact of matching for HLA-DPB1 alleles on the survival of cadaver kidney retransplants was shown. Here we report the results of a new approach, based on matching for HLA-DPB1 epitopes. The analysis is based on 1,478 patients who received a cadaver kidney retransplant between 1988 and 1998. DNA methodology (polymerase chain reaction, sequence-specific oligonucleotides) was used to perform HLA-DPB1 typing. Epitope matching was facilitated with the aid of sequence databases and computer calculations. Matching for the HLA-DP epitopes A, B, E, and F, corresponding to the homonymous hypervariable regions of the second exon of the DPB1 gene, seems to have a greater influence on graft survival than matching for the epitopes C and D. Within a group of 529 retransplants with exactly one allelic HLA-DPB1 mismatch, a significantly better graft outcome was observed when less than two epitope mismatches were found, compared with the group with more than three epitope mismatches (at 2 years: 77.8% vs. 65.8%, P=0.0112). Importantly, patients with two DPB1 allele mismatches who had less than or equal to two epitope mismatches exhibited a significantly better graft outcome than recipients who had one HLA-DPB1 allelic mismatch but more than three epitope mismatches (at 2 years: 77.1% vs. 65.8%, P=0.0488). The findings indicate that the impact of HLA-DPB1 matching on the outcome of kidney retransplants is a result of the predominant immunogenicity of certain epitopes of the HLA-DP molecule. Matching for immunogenic HLA-DPB1 epitopes seems to be functionally more relevant than classical matching at the allelic level.

Frequency of HLA-DPB1 disparities detected by reference strand-mediated conformation analysis in HLA-A, -B, and -DRB1 matched siblings

The role of HLA-DPB1 as transplantation antigen is controversial. The frequency and relevance of HLA-DPB1 mismatch in hematopoietic stem cell transplantation are unknown. To ascertain the rate of HLA-DBP1 mismatch in siblings that had been matched for HLA-A, -B, and -DRB1, reference strand mediated conformation analysis (RSCA) a high resolution HLA typing method was used. Locus-specific primers were used to amplify the HLA-DPB1 locus. The PCR product was then hybridized with two fluorescein-labeled references and the duplexes were analyzed after electrophoresis in a short polyacrylamide gel. Among the 113 pairs of individuals tested, six HLA-DPB1 mismatches were identified, which corresponds to a frequency of 5.31 % (95% confidence interval 3.20%–7.42 %).

Recognition of leukemic blasts by HLA-DPB1-specific cytotoxic T cell clones: a perspective for adjuvant immunotherapy post-bone marrow transplantation.

There is increasing evidence that the immune response plays a role in the prevention of leukemic relapses after allogeneic bone marrow transplantation (BMT). Producing this effect (referred to as the graft-versus-leukemia reaction or GVL) is a current goal of clinical transplantation. At present, all protocols rely on the injection of donor T cells with unknown specificities. In keeping with this approach, we recently proposed the use of a single allogeneic T cell clone transfected with the HSv-tk gene to target an HLA-DPB1 mismatch in the GVH direction. For this strategy to be successful, HLA-DP antigens must be expressed on leukemic cells, which should be recognised by the HLA-DP-specific T cell clone and subsequently destroyed. In the present study, differential expression of HLA-DR, -DQ and -DP was tested by fluorescence using monoclonal antibodies on a panel of 46 acute myeloid leukemias (AML), 28 acute lymphoblastic leukemias (ALL) and 31 chronic lymphocytic leukemias of B cell origin (B-CLL). The vast majority of leukemic cells expressed HLA-DP antigens although with considerable variability. HLA-DPB1 genotyped leukemic cells were used as target cells for an HLA-DPB1*0401-specific T cell clone. Specific recognition of leukemic blasts was demonstrated for 11 out of 11 B-CLL, 11 out of 19 AML and nine out of 16 ALL. These data show that most leukemic blasts are accessible to direct lysis by allogeneic HLA-DP-specific T cells.