Human leukocyte antigen (HLA)-encoded surface molecules present antigenic peptides to T lymphocytes and play a key role in adaptive immune responses. Besides their physiological role of defending the host against infectious pathogens, specific alleles serve as genetic risk factors for autoimmune diseases. For multiple sclerosis (MS), an autoimmune disease that affects the brain and spinal cord, an association with the HLA-DR15 haplotype was described in the early 1970s. This short opinion piece discusses the difficulties of disentangling the details of this association and recent observations about the functional involvement of not only one, but also the second gene of the HLA-DR15 haplotype. This information is not only important for understanding the pathomechanism of MS, but also for antigen-specific therapies.

The HLA-DR15 haplotype is the strongest genetic risk factor for multiple sclerosis (MS), but our understanding of how it contributes to MS is limited. Because autoreactive CD4(+) T cells and B cells as antigen-presenting cells are involved in MS pathogenesis, we characterized the immunopeptidomes of the two HLA-DR15 allomorphs DR2a and DR2b of human primary B cells and monocytes, thymus, and MS brain tissue. Self-peptides from HLA-DR molecules, particularly from DR2a and DR2b themselves, are abundant on B cells and thymic antigen-presenting cells. Furthermore, we identified autoreactive CD4(+) T cell clones that can cross-react with HLA-DR-derived self-peptides (HLA-DR-SPs), peptides from MS-associated foreign agents (Epstein-Barr virus and Akkermansia muciniphila), and autoantigens presented by DR2a and DR2b. Thus, both HLA-DR15 allomorphs jointly shape an autoreactive T cell repertoire by serving as antigen-presenting structures and epitope sources and by presenting the same foreign peptides and autoantigens to autoreactive CD4(+) T cells in MS.

BACKGROUND:The prevalence of multiple sclerosis is associated with the major histocompatibility complex class II DR15 haplotype HLA-DRB1*15:01∼HLA-DRB5*01:01. OBJECTIVE:To assess whether multiple sclerosis progression is associated with the main susceptibility haplotype HLA-DRB1*15:01∼HLA-DRB5*01:01. METHODS:Patients (n = 1230) and healthy controls (n = 2110) were genotyped for HLA-DRB1 and HLA-DRB5. The baseline Expanded Disability Status Scale (EDSS) score was determined and patients were followed for at least 3 years. RESULTS:After follow-up of the consecutive cohort 349 patients were classified as having clinical isolated syndrome and 881 patients as having multiple sclerosis. The susceptibility allele HLA-DRB1*15:01 was more frequent in clinical isolated syndrome (odds ratio 1.56) and multiple sclerosis (odds ratio 3.17) compared to controls. HLA- DRB1*15:01 was the only enriched HLA-DRB1 allele in multiple sclerosis patients. Comparison of clinical characteristics between HLA-DRB1*15:01∼HLA-DRB5*01:01 negative and positive patients with multiple sclerosis showed that baseline EDSS score, disease duration and frequency of the category secondary progressive multiple sclerosis with relapse were increased in the HLA-DRB1*15:01∼HLA-DRB5*01:01 positive group. CONCLUSION:The study confirmed HLA-DRB1*15:01 and HLA-DRB5*01:01 as the main susceptibility alleles and showed weak indirect evidence for a role in progression of the disease.

Some years ago we found a new HLA-DRB1∗13 allele in a family in Germany with roots in Turkey and Armenia. It was found in a male potential stem cell donor, in his own and in his extended family. Sanger sequencing of exon 2 of this allele, later called DRB1∗13:54, revealed 3 nucleotide variations at position 157 (T → A), 158 (C → T) and 166 (C → A). To complete the genomic sequence and to clarify the degree of recombination within this allele, we developed a workflow based on long range PCR (LR-PCR) and next generation sequencing (NGS). Therefore we designed different HLA locus and/or allele specific LR-PCRs and sequenced the generated amplicons on a MiSeq platform (Illumina). The subsequent NGS data evaluation was performed with two different HLA software tools (Omixon Twin, Omixon and NGSengine, GenDx). The phased sequence alignment according to the individual single nucleotide variants (SNVs) pattern present ended up with allele-specific contigs. The final alignment of these contigs was done with AliView (Muscle) and BioEdit (ClustalW) software along with published IMGT/HLA database sequences. The full-length sequence analysis of the described allele unraveled a quite high similarity to the DRB1∗13:24 allele. The evolutionary history of the DRB1∗13:54 could be best explained by a recombination of DRB1∗13:04 (acceptor) with DRB1∗07 (∗07:01-∗07:04, ∗07:07) or DRB1∗12 (∗12:01, ∗12:03, ∗12:05-∗12:08) as donor. With our approach, applying LR-PCR and NGS including phased sequence analysis, we were able to determine the complete gene sequence of HLA-DRB1∗13:54 (from 5’-UTR to 3’-UTR). The most likely evolutionary recombination between the DRB1∗13 allele and the DRB1∗07 or DRB1∗12 alleles seems to be restricted to exon 2 only.

Some years ago, HLA-typing (rSSO & SBT) of a young Turkish patient with Wiskott-Aldrich syndrome (WAS) revealed a DQB1∗03:02:01 in combination with a new HLA-DQB1∗06:02 variant, later named as DQB1∗06:37. The DQB1∗06:37 allele differs from DQB1∗06:02:01 in two non-synonymous nucleotide positions in exon 2 (codon 70: AAC→AAG, Asn→Lys and codon 78: GGG→AGG, Gly→Arg). The DNA sequences outside exon 2 were not determined initially. Complete sequence data for HLA class II alleles are still limited and difficult to obtain due to special features of the sequences itself. It was our intention to develop a workflow based on LR-PCR and NGS to provide the complete genomic sequence of this allele. Therefore, we designed different DQB1 specific LR-PCRs. After DQB1 amplicon generation, NGS (MiSeq, Illumina), data evaluation with two different HLA software tools (NGSengine, GenDx and Omixon Twin, Omixon) we ended up with allele-specific contigs computed relying on a phasing analysis of the individual single nucleotide variants (SNVs) pattern present. The final alignment of these contigs was performed with the BioEdit (ClustalW) software together with the published genomic sequences of the DQB1∗06:02:01, DQB1∗06:37 (exon 2 only) and DQB1∗03:02:01 alleles (IMGT/HLA database, http://www.ebi.ac.uk/imgt/hla/). With our approach, we were able to determine the complete gene sequence of DQB1∗06:37 (from 5'-UTR over all exons and introns to 3′-UTR), which is identical to the published gene sequence of DQB1∗06:02:01 differing only in the two above mentioned nucleotide positions within exon 2. The full-length sequence of the second DQB1 allele (DQB1∗03:02:01) of the patient is identical to the published gene sequence. Applying LR-PCR and NGS including phased sequence analysis we were able to identify the complete gene sequences of both DQB1 alleles (DQB1∗06:37 & DQB1∗03:02:01) of this patient separately. We hope that in the near future it would become easy to identify the complete sequences of HLA-alleles with the combination of these methods. Apart from compatibility testing this would be helpful especially for evolutionary and ancestry studies.

The HLA-DR and -DQ loci are close neighbors on chromosome 6 that are highly linked. Many common associations between HLA-DR and DQ-alleles are known, normally transmitted as HLA-DR̃DQ haplotypes from one generation to another. Reports of very recent genetic rearrangements between HLA-DR and -DQ are rarely found in the literature. In Europeans haplotypes containing DRB1∗15:01, DQB1∗02:01, and DQA1∗05:01 have not been reported before. We report the finding of the rare HLA haplotype A∗24:02̃C∗07:02̃B∗07:02̃MICA∗008:01̃DRB5∗01:01̃DRB1∗15:01̃DQA1∗05:01̃DQB1∗02:01̃DPB1∗04:01 in a German stem cell donor with East Frisian ancestry. Our observation suggests a rare ancestral recombination between the DR and DQ loci. In order to investigate this haplotype, we typed 50/74 members of the family encompassing four generations for HLA classes I and II by serological and molecular methods. The rare haplotype was identified in 12 heterozygous carriers. Furthermore, we identified and further characterized a putative crossing over event resulting in its reversion to a common haplotype.

B cells and their regulation by B‐cell activating factor BAFF are of growing interest in kidney transplantation ( KT x). There is evidence that high serum (s) BAFF leads to increased allosensitization and impaired long‐term graft function. We prospectively investigated sBAFF , peripheral blood lymphocytes ( PBL ), and donor‐specific HLA antibodies ( DSA ) in patients after ABO i with B‐cell depleting rituximab induction treatment and compared them to a group of blood group‐compatible ( ABO c) living donor kidney recipients. Twelve patients after ABO i and 18 after ABO c were included. After rituximab treatment prior to ABO i, B cells remained significantly lower 1 year after KT x (1.2% (0.0–17.8) compared to ABO c of 8.6% (2.8–35.0), p = 0.0004 , and also BAFF ‐R expression was significantly lower in ABO i (p < 0.006) . sBAFF remained elevated 1 year post‐Tx compared to ABO c (3615 ± 1800 vs. 1394 ± 493 pg/mL, p < 0.004) . Kidney function was not significantly different between both groups after 1, 2, and 3 years. The use of rituximab in ABO i together with maintenance immunosuppression leads to significant elevation of sBAFF and lowering of B‐cell numbers for more than 1 year, and this does not correlate with worse 3‐year graft outcome.

This paper presents the fourth German consensus on the selection of donors for an allogeneic hematopoietic stem cell transplantation (HSCT) as agreed by the German Society for Immunogenetics (DGI) and the German Working Party for Bone Marrowand Blood Stem Cell Transplantation (DAG-KBT). It represents the common denominator of over 60 transplant teams and almost 20 immunogenetic search units taking care of over 3000 patients per year in Germany. While the first consensus marked the beginning of the transition from cellular and serological to DNA based methods, this consensus defines high resolution matching for the antigen recognition site of the five most relevant HLA loci as the "gold standard". The document addresses the search for related and unrelated donors as well as the various sources of stem cells, depicts a clear guideline where evidence is mature and discusses options in areas of ongoing research.

Hepatocellular carcinoma (HCC) is the fifth most common malignancy worldwide with a poor prognosis and limited therapeutic options. To aid the development of novel immunological interventions, we studied the breadth, frequency, and tumor-infiltration of naturally occurring CD8+ T-cell responses targeting several tumor-associated antigens (TAA). We used overlapping peptides spanning the entire alpha-fetoprotein (AFP), glypican-3 (GPC-3), melanoma-associated gene-A1 (MAGE-A1) and New York-esophageal squamous cell carcinoma-1 (NY-ESO-1) proteins and major-histocompatibility-complex-class-I-tetramers specific for epitopes of MAGE-A1 and NY-ESO-1 to analyze TAA-specific CD8+ T-cell responses in a large cohort of HCC patients. After nonspecific expansion in vitro, we detected interferon-γ (IFN-γ)-producing CD8+ T cells specific for all four TAA in the periphery as well as in liver and tumor tissue. These CD8+ T-cell responses displayed clear immunodominance patterns within each TAA, but no consistent hierarchy was observed between different TAA. Importantly, the response breadth was highest in early-stage HCC and associated with patient survival. After antigen-specific expansion, TAA-specific CD8+ T cells were detectable by tetramer staining but impaired in their ability to produce IFN-γ. Furthermore, regulatory T cells (Treg) were increased in HCC lesions. Depletion of Treg from cultures improved TAA-specific CD8+ T-cell proliferation but did not restore IFN-γ-production. Conclusion: Naturally occurring TAA-specific CD8+ T-cell responses are present in patients with HCC and therefore constitute part of the normal T-cell repertoire. Moreover, the presence of these responses correlates with patient survival. However, the observation of impaired IFN-γ production suggests that the efficacy of such responses is functionally limited. These findings support the development of strategies that aim to enhance the total TAA-specific CD8+ T-cell response by therapeutic boosting and/or specificity diversification. However, further research will be required to help unlock the full potential of TAA-specific CD8+ T-cell responses. (HEPATOLOGY 2014;59:1415-1426)

Der vorliegende 4. deutsche Konsensus zur immungenetischen Spenderauswahl für die allogene Stammzelltransplantation wurde von der Deutschen Gesellschaft für Immungenetik (DGI) und der Deutschen Arbeitsgemeinschaft für Knochenmark- und Blutstammzelltransplantation (DAG-KBT) gemeinsam erarbeitet und verabschiedet. Er stellt den gemeinsamen Nenner von mehr als 60 Transplantationseinheiten und fast 20 immungenetischen Sucheinheiten dar, die mehr als 3000 deutsche Patienten jährlich betreuen. Während der 1. Konsensus im Jahre 1996 den Anfang der Ablösung von zellulären und serologischen Methoden der HLA-Testung durch molekulargenetische Verfahren darstellte, wird nun die hochaufgelöste Bestimmung der Antigenbindungsstelle der HLA-Moleküle der 5 wichtigsten Genorte als Standard definiert. Das vorliegende Dokument behandelt die Suche nach verwandten und nicht-verwandten Spendern und alle infrage kommenden Stammzellquellen. Bei Sachverhalten, für die eine eindeutig wissenschaftliche Evidenz vorliegt, gibt dieser Konsensus eine klare Richtschnur vor, während es sonst, soweit möglich, die Handlungsoptionen beschreibt.