Matching donor and recipient based on predicted indirectly recognizable human leucocyte antigen epitopes.

The predicted indirectly recognizable human leucocyte antigen (HLA) epitopes (PIRCHE) algorithm is a novel in silico algorithm to determine donor-recipient compatibility. The PIRCHE algorithm determines donor-recipient compatibility by counting the number of mismatched HLA-derived epitopes that are involved in indirect T-cell alloimmune responses; these epitopes are designated as PIRCHE. Over the last few years, the PIRCHE algorithm has been investigated in both hematopoietic stem cell transplantation and solid organ transplantation. This review describes the theory of the algorithm, its application in transplantation, and highlights the future perspectives on the clinical application of the PIRCHE algorithm.

A phase I/II minor histocompatibility antigen-loaded dendritic cell vaccination trial to safely improve the efficacy of donor lymphocyte infusions in myeloma.

Allogeneic stem cell transplantation (allo-SCT) with or without donor lymphocyte infusions (DLI) is the only curative option for several hematological malignancies. Unfortunately, allo-SCT is often associated with GvHD, and patients often relapse. We therefore aim to improve the graft-versus-tumor effect, without increasing the risk of GvHD, by targeting hematopoietic lineage-restricted and tumor-associated minor histocompatibility antigens using peptide-loaded dendritic cell (DC) vaccinations. In the present multicenter study, we report the feasibility, safety and efficacy of this concept. We treated nine multiple myeloma patients with persistent or relapsed disease after allo-SCT and a previous DLI, with donor monocyte-derived mHag-peptide-loaded DC vaccinations combined with a second DLI. Vaccinations were well tolerated and no occurrence of GvHD was observed. In five out of nine patients, we were able to show the induction of mHag-specific CD8+ T cells in peripheral blood. Five out of nine patients, of which four developed mHag-specific T cells, showed stable disease (SD) for 3.5-10 months. This study shows that mHag-based donor monocyte-derived DC vaccination combined with DLI is safe, feasible and capable of inducing objective mHag-specific T-cell responses. Future research should focus on further improvement of the vaccination strategy, toward translating the observed T-cell responses into robust clinical responses.

Efficacy of host-dendritic cell vaccinations with or without minor histocompatibility antigen loading, combined with donor lymphocyte infusion in multiple myeloma patients.

Donor lymphocyte infusions (DLI) can induce durable remissions in multiple myeloma (MM) patients, but this occurs rather infrequently. As the graft-versus-tumor (GvT) effect of DLI depends on the presence of host-dendritic cells (DCs), we tested in a phase I/II trial whether the efficacy of DLI could be improved by simultaneous vaccination with host-DCs. We also analyzed the possibility of further improving the GvT effect by loading the DCs with peptides of mismatched hematopoietic cell-specific minor histocompatibility antigens (mHags). Fifteen MM patients not responding to a first DLI were included. Eleven patients could be treated with a second equivalent dose DLI combined with DC vaccinations, generated from host monocytes (moDC). For four patients, the DC products did not meet the quality criteria. In four of the treated patients the DCs were loaded with host mHag peptides. Toxicity was limited and no acute GvHD occurred. Most patients developed objective anti-host T-cell responses and in one patient a distinct mHag-specific T-cell response accompanied a temporary clinical response. These findings confirm that DLI combined with host-DC vaccination, either unloaded or loaded with mHag peptides, is feasible, safe and capable of inducing host-specific T-cell responses. The limited clinical effects may be improved by developing more immunogenic DC products or by combining this therapy with immune potentiating modalities like checkpoint inhibitors.

Biomarker profiling of steroid-resistant acute GVHD in patients after infusion of mesenchymal stromal cells.

We performed a prospective phase II study to evaluate clinical safety and outcome in 48 patients with steroid-refractory grade II-IV acute graft-versus-host disease (aGVHD) treated with mesenchymal stromal cells (MSCs). Clinical outcomes were correlated to comprehensive analyses of soluble and cellular biomarkers. Complete resolution (CR) of aGVHD at day 28 (CR-28) occurred in 12 (25%) patients, CR lasting >1 month (CR-B) occurred in 24 (50%) patients. One-year overall survival was significantly improved in CR-28 (75 versus 33%, P=0.020) and CR-B (79 versus 8%, P<0.001) versus non-CR patients. A six soluble biomarker-panel was predictive for mortality (HR 2.924; CI 1.485-5.758) when measured before MSC-administration. Suppression of tumorigenicity 2 (ST2) was only predictive for mortality 2 weeks after but not before MSC-administration (HR 2.389; CI 1.144-4.989). In addition, an increase in immature myeloid dendritic cells associated with decreased mortality (HR 0.554, CI 0.389-0.790). Patients had persisting T-cell responses against defined virus- and leukemia-associated antigens. In conclusion, our data emphasize the need to carefully assess biomarkers in cohorts with homogeneous GVHD treatments. Biomarkers might become an additional valuable component of composite end points for the rapid and efficient testing of novel compounds to decrease lifecycle of clinical testing and improve the success rate of phase II/III trials.

The novel HLA-A*24:215 allele, identified by sequencing-based typing of a stem cell transplant patient and the sibling donor.

We identified a new human leukocyte antigen-A allele, designated HLA-A*24:215, by sequencing-based typing of a stem cell transplant patient.

The novel HLA-B*44:02:27 allele, identified by sequencing-based typing of a candidate stem-cell donor.

The HLA-B*44:02:27 allele strongly resembles the HLA-B*44:02:01:01 allele with respect to HLA-C association and haplotype constitution.

16th IHIW: international histocompatibility working group in hematopoietic cell transplantation.

The International Histocompatibility Working Group is a collaborative international effort to understand the HLA and non-HLA genetics of the transplantation barrier. The Working Group is comprised of experts in the fields of histocompatibility and immunogenetics, hematopoietic cell transplantation and outcomes research. Data for 25 855 unrelated donor transplants were submitted in support of research studies for the 16th International Histocompatibility Workshop. Active investigation is in progress in seven key areas: the impact of HLA matching, role of race and ethnicity, identification of permissible HLA mismatches, haplotype-associated determinants, minor histocompatibility antigens, immune response genes and KIR genetics. New hypotheses for the 16th workshop were developed for immunogenetic studies in cord blood and haploidentical-related donor transplantation.

Towards effective and safe immunotherapy after allogeneic stem cell transplantation: identification of hematopoietic-specific minor histocompatibility antigen UTA2-1.

Donor T cells directed at hematopoietic system-specific minor histocompatibility antigens (mHags) are considered important cellular tools to induce therapeutic graft-versus-tumor (GvT) effects with low risk of graft-versus-host disease after allogeneic stem cell transplantation. To enable the clinical evaluation of the concept of mHag-based immunotherapy and subsequent broad implementation, the identification of more hematopoietic mHags with broad applicability is imperative. Here we describe novel mHag UTA2-1 with ideal characteristics for this purpose. We identified this antigen using genome-wide zygosity-genotype correlation analysis of a mHag-specific CD8(+) cytotoxic T lymphocyte (CTL) clone derived from a multiple myeloma patient who achieved a long-lasting complete remission after donor lymphocyte infusion from an human leukocyte antigen (HLA)-matched sibling. UTA2-1 is a polymorphic peptide presented by the common HLA molecule HLA-A*02:01, which is encoded by the bi-allelic hematopoietic-specific gene C12orf35. Tetramer analyses demonstrated an expansion of UTA2-1-directed T cells in patient blood samples after several donor T-cell infusions that mediated clinical GvT responses. More importantly, UTA2-1-specific CTL effectively lysed mHag(+) hematopoietic cells, including patient myeloma cells, without affecting non-hematopoietic cells. Thus, with the capacity to induce relevant immunotherapeutic CTLs, it's HLA-A*02 restriction and equally balanced phenotype frequency, UTA2-1 is a highly valuable mHag to facilitate clinical application of mHag-based immunotherapy.

Predictive impact of allele-matching and EBMT risk score for outcome after T-cell depleted unrelated donor transplantation in poor-risk acute leukemia and myelodysplasia.

Many parameters predict for outcome after unrelated donor (URD) allogeneic hematopoietic stem cell transplantation (alloSCT). High-resolution HLA-matching significantly impacts outcome and also the European Group of Blood and Marrow Transplantation (EBMT) risk score, based on patient age, disease stage, donor type, time from diagnosis to SCT and gender combination, may predict for non-relapse mortality and overall survival (OS). We evaluated the individual and combined effects of allele-matching and the EBMT risk score in 327 patients with poor-risk acute leukemia or myelodysplasia, who received a T-cell depleted URD alloSCT. Matching for HLA-A, -B, -C and -DRB1 alleles (8/8 match) was associated with a 5-year OS of 40% compared with 30% for mismatched (≤7/8) pairs (P=0.02). Patients with EBMT risk scores of 1-2, 3, 4 and 5-7 had 5-year OS estimates of 53, 43, 30 and 20%, respectively (P<0.001). The favorable prognostic impact of an 8/8 donor was most pronounced if the EBMT risk score was low (1-2). Five-year OS was 74±8% vs 39±11% for fully matched patients with a low-risk EBMT score as compared with EBMT low-risk patients with ≤7/8 donors. These data underscore the importance of incorporating both the EBMT risk score and the degree of high-resolution HLA-matching in the risk assessment prior to URD alloSCT.

Minor histocompatibility antigens: targets for tumour therapy and transplant tolerance.

Minor histocompatibility (H) antigens are allogeneic targets of T-cell mediated immune reactivity following allogeneic haematopoietic stem cell transplantation. Depending on the tissue expression profile of the minor H antigens this immune reactivity clinically results in graft-vs-host disease or in graft-vs-leukaemia effects. Targeting haematopoietic-specific minor H antigens by adoptive immunotherapy will evoke leukaemia-specific allo-immune responses, thereby enhancing graft-vs-leukaemia effects. Recently, a novel alternative role for minor H antigens in transplantation has been described; minor H antigen-specific T cells appear to be able to regulate allo-immune responses after solid organ transplantation. This diversity in immune reactivity suggests a broad clinical potential of minor H antigens, both in haematopoietic stem cell transplantation and in solid organ transplantation.

Mycobacterium leprae-specific, HLA class II-restricted killing of human Schwann cells by CD4+ Th1 cells: a novel immunopathogenic mechanism of nerve damage in leprosy.

Peripheral nerve damage is a major complication of reversal (or type-1) reactions in leprosy. The pathogenesis of nerve damage remains largely unresolved, but detailed in situ analyses suggest that type-1 T cells play an important role. Mycobacterium leprae is known to have a remarkable tropism for Schwann cells of the peripheral nerve. Reversal reactions in leprosy are often accompanied by severe and irreversible nerve destruction and are associated with increased cellular immune reactivity against M. leprae. Thus, a likely immunopathogenic mechanism of Schwann cell and nerve damage in leprosy is that infected Schwann cells process and present Ags of M. leprae to Ag-specific, inflammatory type-1 T cells and that these T cells subsequently damage and lyse infected Schwann cells. Thus far it has been difficult to study this directly because of the inability to grow large numbers of human Schwann cells. We now have established long-term human Schwann cell cultures from sural nerves and show that human Schwann cells express MHC class I and II, ICAM-1, and CD80 surface molecules involved in Ag presentation. Human Schwann cells process and present M. leprae, as well as recombinant proteins and peptides to MHC class II-restricted CD4(+) T cells, and are efficiently killed by these activated T cells. These findings elucidate a novel mechanism that is likely involved in the immunopathogenesis of nerve damage in leprosy.

Daily migraine with visual aura associated with an occipital arteriovenous malformation.

A 51-year-old woman with daily attacks of migraine with visual aura is described. The aura always occurred on the right and the headache always on the left side of the head, suggesting a structural lesion in the left occipital lobe. The lesion appeared to be an arteriovenous malformation of which almost full obliteration resulted in a decrease in frequency of the aura and in intensity of the headache. Subsequent treatment of borderline hypothyroidism with levothyroxine brought about a dramatic improvement in frequency of both the aura and the headache. The case is discussed in the light of our present understanding of the pathogenesis of the migraine attack.

Novel mechanisms in the immunopathogenesis of leprosy nerve damage: the role of Schwann cells, T cells and Mycobacterium leprae.

The major complication of reversal (or type 1) reactions in leprosy is peripheral nerve damage. The pathogenesis of nerve damage remains largely unresolved. In situ analyses suggest an important role for type 1 T cells. Mycobacterium leprae is known to have a remarkable tropism for Schwann cells that surround peripheral axons. Reversal reactions in leprosy are often accompanied by severe and irreversible nerve destruction and are associated with increased cellular immune reactivity against M. leprae. Thus, a likely immunopathogenic mechanism of Schwann cell and nerve damage in leprosy is that infected Schwann cells process and present antigens of M. Leprae to antigen-specific, inflammatory type 1 T cells and that these T cells subsequently damage and lyse infected Schwann cells. Previous studies using rodent CD8+ T cells and Schwann cells have revealed evidence for the existence of such a mechanism. Recently, a similar role has been suggested for human CD4+ T cells. These cells may be more important in causing leprosy nerve damage in vivo, given the predilection of M. leprae for Schwann cells and the dominant role of CD4+ serine esterase+ Th1 cells in leprosy lesions. Antagonism of molecular interactions between M. leprae, Schwann cells and inflammatory T cells may therefore provide a rational strategy to prevent Schwann cell and nerve damage in leprosy.

Cloning, expression and significance of MPT53 for identification of secreted proteins of Mycobacterium tuberculosis.

Based on our N -terminal amino acid sequence of MPT53 and a deduced DNA sequence, we searched for the corresponding gene in the Mycobacterium tuberculosis genomic sequence at the Sanger centre, localizing mpt53 close to mpt70 and mpt83. The gene was cloned and expressed, followed by purification of MPT53 to homogeneity from recombinant M. smegmatis culture fluid. In MPT53 there is 60 % identity with the active site of thioredoxin of M. tuberculosis (MPT46) with two cysteins in a CXXC motif, but MPT53 could not serve as an alternative substrate for thioredoxin reductase. Testing for IgM and IgG1 anti-MPT53 in cattle sera showed that MPT53 is immunogenic following natural and experimental infection with M. bovis. Cloning of mpt53 represents cloning of the last of the 10 proteins originally defined as "secreted proteins" of M. tuberculosis and M. bovis based on determination of their "Localization index" (LI) (J Gen Microbiol 1991;137 : 875-84). The need for a precise definition of the term "secreted protein" is discussed. So far we have observed full concordance between occurrence of an LI value indicating secretion of a protein and occurrence of a signal sequence in the corresponding gene. Signal sequence independent protein secretion in mycobacteria may occur for a limited number of proteins and remains to be established.

Angiographic changes suggestive of vasospasm in migraine complicated by stroke.

A 30-year-old woman with a history of common migraine developed a permanent left homonymous hemianopia during a typical headache. CT scan demonstrated a right posterior cerebral infarction and angiography showed irregular narrowing of the ipsilateral posterior cerebral artery, suggestive of vasospasm. In the case no risk factors for atherosclerotic stroke were present except for smoking, and no other causes of stroke could be found.

Inflammatory pleuropulmonary fibrosis in essential fatty acid deficient rats and the lack of response to methysergide.

In view of the association between essential fatty acid (EFA) deficiency and human cystic fibrosis, we have investigated the possible occurrence of pulmonary disease in rats fed an EFA deficient (EFAD) diet for 40 weeks. In contrast to a few slight spontaneous lesions consisting of pleural membrane hyperplasia, which were found in the lungs of control rats, a much greater incidence of fibrotic lesions was observed in the lungs of EFAD rats. These pleuropulmonary fibroses extended from the hyperplastic pleural membrane into the alveoli and were characterized by collagen deposition and marked macrophage infiltration to the extent that, in some cases, the alveolar septa were completely obstructed by inflammatory exudate. These findings lend indirect support to the contention that EFA deficiency plays a role in the aetiology of cystic fibrosis, at least with regard to pulmonary lesions. Administration of methysergide (10 mg/kg/day, p.o.) for a total of 11 weeks, did not alter the incidence of fibrosis in the lungs of EFAD rats, despite the finding that a man who had developed pleuropulmonary fibrosis as a result of chronic methysergide treatment exhibited a relative serum EFA deficiency. While a relative EFA deficiency may be a predisposing factor for the induction of fibrosis by chronic methysergide treatment, our data are not sufficient to make a decision upon this hypothesis.

The management of os odontoideum. Analysis of 37 cases.

Thirty-seven patients treated for os odontoideum are reviewed. In 20 patients the treatment was conservative and in 17 consisted of occipitocervical or atlanto-axial fusion. Two patients died after the operation and another, who lived abroad, was lost to follow-up. The remaining 34 patients were followed up for an average of eight years: 19 improved, 14 were unchanged and one deteriorated. In the subgroup of 25 patients without cord signs, there were no significant differences between the two modes of treatment. Analysis of the radiological features of the upper cervical spine in 21 patients revealed a minimal sagittal diameter of less than 13 millimetres to be associated with a high risk of permanent cord damage. There was no correlation with the degree of instability per se. On the basis of this analysis, guidelines are suggested for the management of patients with an os odontoideum.