So far 11 different amino acid variants of the HLA-DRB1*01 family have been reported. We here describe the identification of a new HLA-DRB1*01 allele in a healthy female Caucasian. The allele was detected by sequencing-based typing during high-resolution typing of a potential unrelated donor from the North German Bone Marrow Registry (NKR). Compared with DRB1*010101, to which it is closest, the new variant is characterized by a new replacement mutation (G-->T) at nucleotide position 202 of exon 2, resulting in the amino acid substitution Arg-->Leu at position 72. Because this amino acid position is not involved in peptide binding or T-cell interaction, it is likely to represent a permissive mismatch to the more common HLA-DRB1*0101 allele.

Adult↗

PubMed2005

The variation of the novel allele HLA-B0739 suggests low alloreactivity when mismatched with HLA-B0702.

We here report the identification of a new HLA-B*07 allele in a male Caucasian. The new allele was initially typed as B*0713 by sequence-specific primed PCR. Because of the infrequence of that allele, a sequencing-based typing was performed to confirm that result. This yielded the detection of the novel allele. It is closest to B*070201, while it differs from B*0713 in 12 positions in exon 2. Compared to B*070201, the new variant is characterized by a non-synonymous nucleotide exchange (C-->T) at nucleotide position 118 of exon 2. Previously, this was considered a constant position, suggesting that it is likely to be caused by a single-point mutation. It results in the amino acid exchange Ala-->Val at position 40 of the mature polypeptide. As this position is located in an outer loop of the HLA molecule, it is highly unlikely to affect peptide binding or T-cell receptor interaction. Thus, the newly found allele should have a low alloreactive potential in case of a mismatch to the most common HLA-B allele B*0702.

Alleles↗

PubMed2005

Non-expression of HLA-A*0283N.

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Base Sequence↗

PubMed2005

An amino acid contributing to pockets A, B, and D of the peptide-binding groove is altered in A*0315.

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Adult↗

PubMed2004

HistoCheck: rating of HLA class I and II mismatches by an internet-based software tool.

HLA polymorphism is a major barrier for hematopoietic stem cell and solid organ transplantation. To estimate the allogeneic potential between HLA-mismatched stem cell donor/recipient pairs, we recently proposed a matching score (dissimilarity index) that is based on the structural data of HLA class I molecules, and on the functional similarity of amino acids (AA). This first approach revealed new features about presumptive subtype allogenicities within the HLA-A*23 and A*24 groups. We have now developed an internet-based software tool ("HistoCheck") that is capable to assess the allogenicity (matching score) between any pair of clinically relevant HLA class I, and also class II, alleles. Newly described HLA sequences will be regularly integrated into the database according to the nomenclature for factors of the HLA system updates. The software is intended to be a first step for estimating the allogenicity of HLA mismatches in peculiar clinical settings, as long as there are no reliable in vitro or clinical studies available. The algorithm can later be modified according to functional data, for example, peptide-binding specificities. With the extension of the sequence similarity concept to all clinically relevant HLA class I and II loci, HistoCheck may contribute to prevent HLA mismatching being a matter of chance.

Algorithms↗

PubMed2004

Impact of tobacco smoking on platelet function in apheresis products in vitro.

BACKGROUND AND OBJECTIVES: The aim of this study was to analyse the platelet function, over a 5-day time-period, of apheresis-derived platelet concentrates obtained from smokers and non-smokers. MATERIALS AND METHODS: Smoker and non-smoker plateletpheresis products were investigated on days 1, 3 and 5 of storage. Receptor expression (as evaluated by flow cytometry) and the platelet aggregation response were measured. RESULTS: There was only a slight loss of platelet function in apheresis products from smokers compared to non-smokers. CONCLUSIONS: Smoking does not significantly change the quality of platelet preparations. The current practice, of not to exclude smokers from platelet donation, can be continued.

Adenosine Diphosphate↗

PubMed2004

The phylogenies of introns 4-7 demonstrate an inconsistent pattern between human leukocyte antigen-C group topologies.

In this study, we have sequenced introns 4-7 in 31 human leukocyte antigen-C (HLA-C) alleles representing all allelic groups. Intron sequences show a patchwork pattern of polymorphism. Bootstrap support for phylogenetic lineages and for differentiation between groups is limited due to the high homology of intron sequences, where the substitution of a single nucleotide may lead to the assignment to different clusters. The intron data suggest the idea of a Cw*06/Cw*12 family, which is closely related to a hypothetical Cw*05/Cw*08 family. Moreover, a third family consisting of Cw*01/Cw*04/Cw*18 may exist. The intron data compiled in our study may be the basis for further sequencing studies. The detection of three novel alleles (Cw*0401new, Cw*140201new, and Cw*1701new) suggests that the HLA-C polymorphism might have been strongly underestimated to date.

Alleles↗

PubMed2004

Eight novel MICB alleles, including a null allele, identified in gastric MALT lymphoma patients.

MICA and MICB, as members of the major histocompatibility complex (MHC) class I-chain-related genes (MIC), encode stress-inducible glycoproteins that act as activating ligands for NKG2D and gammadelta T-cell receptor-bearing cells. We here describe the identification of eight novel MICB variants, including a null allele, which were identified in peripheral blood leukocytes of gastric MALT lymphoma patients. Only two of the novel alleles are characterized by point mutations, whereas the other variants display a recombination of known exonic MICB sequences that may be best explained by intragenic conversions. The novel MICB null allele is characterized by a Cytosin (C) deletion in a stretch of four Cs beginning from nucleotide 135 of exon 2 that leads to a premature stop codon (TGA) at codon 66.

Alleles↗

PubMed2004

Immunogenetics of HLA null alleles: implications for blood stem cell transplantation.

The transplantation of haematopoietic stem cells is a potentially curative therapy for a variety of haematological and non-haematological diseases. Matching of donor and recipient for human leucocyte antigens (HLA) is pivotal for the success of blood stem cell transplantation. HLA null alleles are characterized by the lack of a serologically detectable product. Because serological HLA diagnostics are increasingly replaced by DNA-based typing methods considering only small regions of the genes, null alleles may be misdiagnosed as normally expressed variants. The failure to identify an HLA null allele as a non-expressed variant in the stem cell transplantation setting may result in an HLA mismatch that is highly likely to stimulate allogeneic T cells and to trigger graft-vs-host disease. For some HLA null alleles, the translation into a truncated polypeptide chain seems possible, which thus might act as minor histocompatibility antigens. Because the prevalence of HLA null alleles may be around 0.3% or even higher, a screening strategy for HLA null alleles should, therefore, be implemented in the clinical laboratory. It may consist of the combination of serology and standard molecular typing techniques. As the standard molecular techniques are sometimes troublesome especially for characterizing the cytosine island at the 5' end of HLA class I exon 4 and need continuously be updated, an alternative approach may consist of sequencing all samples from genomic DNA for exons 2-3 or 4 (class I) or exon 2 (class II), including the adjacent intron splicing sites. This approach will detect 36/40 so far known non-expressed variants and has the potential to easily uncover novel variants, thus essentially minimizing the risk of overlooking these challenging variants.

DNA↗

PubMed2004

Collection of two consecutive neutrophil concentrates for transfusion from donors mobilized with glycosylated granulocyte-CSF plus dexamethasone.

BACKGROUND: The objective of this study was to establish a mobilization and apheresis regimen for collection of two consecutive polymorphonuclear neutrophil (PMN) concentrates from the same donor. STUDY DESIGN AND METHODS: In this prospective study, 111 healthy unrelated volunteers underwent either one (Group 1, n = 57) or two consecutive granulocyte apheresis procedure (Group 2, n = 54) using the a cell separator (Spectra). Both Group 1 and 2 donors were initially mobilized with glycosylated G-CSF 6.0 micro g per kg (range, 5.2-7.0 micro g/kg) subcutaneously plus oral dexa-methasone (DXM, 8 mg) and underwent granulocyte apheresis (GA-1) 16 hours (range, 13-18 hr) after initial G-CSF+DXM. Group 2 donors were remobilized with a second DXM dose of 8 mg (n = 13), 4 mg (n = 15), 1.5 mg (n = 13), or none (n = 13), and a second apheresis (GA-2) was run 40 hours (range, 37-42 hr) after G-CSF+DXM administration and 12 hours after remobilization with DXM alone. RESULTS: Based on equivalent median preapheresis WBC and PMN counts of around 35 x 10(9) WBCs per L and 33 x 10(9) PMNs per L after initial mobilization the GA-1 yields were 85 x 10(9) PMNs per U (range, 34-150) in Group 1 and 75 x 10(9) PMNs per U (range, 35-135) in Group 2 (p = 0.14, NS). In Group 2, median preapheresis values of 19.6 x 10(9) WBCs per L (range, 9.5-37.0) and 16.6 x 10(9) PMNs per L (range, 8.8-34.8) were measured after remobilization and GA-2 yields of 49 x 10(9) WBCs per U (range, 26-113) and 42 x 10(9) PMNs per U (range, 21-95) were obtained. Borderline statistical differences in the GA-2 yields were observed from the remobilized donors: 8 mg: 36 x 10(9) PMNs per U (range, 23-60); 4 mg: 47 x 10(9) PMNs per U (range, 21-56) (p </= 0.04); 1.5 mg: 45 x 10(9) PMNs per U (range, 23-79); placebo: 36 x 10(9) PMNs per U (range, 26-95) (p </= 0.04). CONCLUSION: Two consecutive neutrophil concentrates for transfusion can be obtained after single stimulation with Lenograstim+DXM. A second application of DXM alone is necessary, but of limited value.

Adult↗

PubMed2003

A comparative study of adverse reactions occurring after administration of glycosylated granulocyte colony stimulating factor and/or dexamethasone for mobilization of neutrophils in healthy donors.

Both granulocyte colony-stimulating factor (G-CSF) and dexamethasone (DXM) are used for neutrophil (PMN) mobilization and collection. This prospective study was aimed to evaluate and compare the rate, severity and clinical significance of adverse reactions of these drugs alone and in combination in healthy donors. PMN mobilization was carried out using dexamethasone alone (8 mg orally; n=25) or glycosylated G-CSF alone (Lenograstim, 5 microg/kg subcutaneously, n=24) or in combination (n=23) prior to a standard granulocyte apheresis on the Spectra cell separator. The number of PMNs counted in the mobilized peripheral blood of the donors was 7.0 (3.6-20.4) x10(9)/L (DXM), 25.2 (15.5-49.7) x10(9)/L (G-CSF), and 31.6 (20.0-43.0) x10(9)/L (G-CSF+DXM), corresponding to PMN apheresis yields of 13 (8-43) x10(9)/U, 56 (34-118) x10(9)/U, and 83 (33-117) x10(9)/U, respectively. The three groups had comparable percentages of donors with at least one adverse effect (ranging from 75 to 80%), but the G-CSF-containing regimens were generally more toxic, as was reflected by higher percentages of donors with moderate to severe adverse reactions and higher overall severity scores of 2.28 (G-CSF) and 2.08 (G-CSF+DXM) compared with 1.33 in the DXM group ( p<or=0.001). With G-CSF alone, pain symptom complexes were more frequent, more severe, and more often triggered requests for analgesics (9/47 donors; 19%) and unwillingness to give further neutrophil donations (2/47 donors; 4%). The addition of DXM to G-CSF diminished some symptoms, particularly bone pain, headache and the frequency of requests for analgesics. The predominant symptoms in the DXM alone group were mild gastrointestinal complaints. We conclude that G-CSF stimulation improved neutrophil mobilization and apheresis yields at the expense of donor tolerability. Compared with G-CSF alone, the combination G-CSF and DXM did not increase the quantity or the severity of donor symptoms.

Adjuvants, Immunologic↗

PubMed2003

Presentation assessment of minor histocompatibility antigens by predictive proteasomal cleavage analysis.

Minor histocompatibility peptides (mHps) derived from polymorphic segments of endogenous proteins are thought to be targets for graft-versus-host and graft-versus-leukemia reactions after HLA-identical stem cell transplantation. A great majority of antigenic peptides is generated by fragmentation of proteins in the course of proteasomal processing. An algorithm was recently developed to predict cleavage sites during proteasomal processing. We tested the accuracy of the algorithm to predict mHps using 18 amino acid (AA) sequences of minor histocompatibility antigens (mHags) encoded by autosomal genes representing single nucleotide polymorphisms or by Y-chromosomal genes. The algorithm correctly predicted the C-termini of 11 of 13 experimentally confirmed mHps: 1) Correct prediction of C- and N-termini, e.g., for HA-1(H); 2) Correct prediction of C- and N-termini while anticipating intra-epitope cleavage sites, e.g., for SMCY-A*0201; 3) Correct prediction of C-termini and N-terminal extensions, e.g., for HA-8(R/V); and 4) Correct prediction of C-termini and N-terminal extensions while anticipating intra-epitope cleavage sites, e.g., for UTY-B8. Analysis of experimentally unconfirmed allelic counterparts of four autosomal mHags showed that AA substitutions either led to the insertion of an epitope-destroying cleavage site (e.g., in HA-1(R)) or abolished the correct C-terminus (e.g., in HA-2(M)). The proteasomal processing algorithm provides reliable data on the generation of mHps and forecasts their presence or absence. Combined with MHC class I ligand prediction, it can be a useful tool for the prediction of generation and presentation of new CTL epitopes derived from minor histocompatibility antigens.

Algorithms↗

PubMed2003

The nature of introns 4-6 suggests reduced lineage specificity in HLA-B alleles.

For most HLA-B alleles, coding sequences of the 3' part of the genes still need to be determined, and sequences of the 3' noncoding regions have yet to be studied systematically. In this study, we have determined the sequences of introns 4-6 in all HLA-B allelic groups, and computed nucleotide substitution rates and phylogenetic relationships. These sequences demonstrated an inconsistent pattern of intralineage specificity, intralineage diversity, and interlineage diversity that is best characterized by a patchwork pattern. Apart from phylogenetic studies about HLA diversity and diversification, the sequence data obtained in our study may prove valuable for haplotype-specific sequencing of the 3' part of HLA-B and for the explanation of recombination events in newly described HLA-B alleles.

Alleles↗

PubMed2002

Successful outcome of acute graft-versus-host disease in a liver allograft recipient by withdrawal of immunosuppression.

BACKGROUND: Graft-versus-host disease (GVHD) after liver transplantation is uncommon, and the outcome is almost always fatal. Since 1987, about 30 cases have been described, and patient survival is mostly exceptional. METHODS: A 29-year-old man underwent retransplantation due to chronic cholestatic syndrome, 5 years after his first liver transplantation. Indication for the first liver transplantation was acute liver failure caused by exsiccosis. After the second transplantation, the patient had an initially uneventful course, developing thrombocytopenia at day 21 followed by skin rash and septic complications. Diagnosis of acute GVHD was made by using serological techniques for HLA-A and HLA-DRB and subsequently by fluorogenic sequence-specific primed polymerase chain reaction. In addition, donor lymphocytes were marked by immunohistochemical methods via biopsies of the skin. Immunosuppressive therapy was withdrawn to allow the patient's own immune system to eliminate donor cells. RESULTS: By withdrawing the immunosuppressive therapy, clinical and morphological signs of GVHD vanished. The patient is doing well without recurrence 13 months after transplantation. CONCLUSION: Withdrawal of immunosuppressive therapy is a promising approach in the treatment of acute GVHD to allow the patient's immune system to reconstitute itself, reject offending lymphocytes, and avoid lethal septic complications.

Acute Disease↗