Peptide-binding motif of HLA-A*6603.

The peptide motif of HLA-A*6603 was determined and compared with the available data on the peptide motifs of A*6601 and A*6602. A*6601 differs from A*6602 by two amino acids at positions 90 (Asp90Ala; outer loop) and 163 (Arg163Glu; pocket A). A*6603 differs from A*6601 and A*6602 by a single amino-acid exchange at position 70 (His70Gln; pockets A, B and C).

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.

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.

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.

A single amino-acid polymorphism in pocket A of HLA-A*6602 alters the auxiliary anchors compared with HLA-A*6601 ligands.

In this study we have sequenced peptides eluted from a truncated recombinant HLA-A*6602 molecule, and compared their features with data reported for peptides presented in the A*6601 molecule. A striking change in the amino-acid binding preferences was observed at peptide position P1, which interacts with pocket A of the HLA peptide-binding region. For A*6601, aspartic acid and glutamic acid, both of which possess polar acidic side-chains, have been described as auxiliary anchors.

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.

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 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.

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.

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.

[Effect of donor/recipient HLA-B match on transplant survival in patients with liver transplants with HBV cirrhosis].

We retrospectively analysed 87 recipients of orthotopic liver transplants with HBV cirrhosis for the impact of HLA-B matching on postoperative outcome. Our data demonstrate a significantly increased graft survival for patients with 1 or 2 HLA-B matches (p < 0.02).

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.

The nature of diversity and diversification at the ABO locus.

In this study we analyzed the complete genomic sequences, except intron 1, and 2 regulatory regions of 6 common (ABO*A101, ABO*A201, ABO*B101, ABO*O01, ABO*O02, and ABO*O03) and 18 rare ABO alleles, 3 of which were new. This was done by phylogenetic analysis and correlating sequence data with the ABO phenotypes. The study revealed multiple polymorphisms in noncoding regions.

Systematic analysis of the ABO gene diversity within exons 6 and 7 by PCR screening reveals new ABO alleles.

Background: Mutations critical for ABO blood group phenotypes have predominantly been found in exons 6 and 7 of the ABO gene, both of which encode the catalytic domain of ABO glycosyltransferase. To design rapid and reliable ABO genotyping assays, a profound knowledge of the prevalent alleles is required and a reliable sequence database needs to be established.

Study Design And Methods: A PCR screening system was established consisting of 102 different PCRs, each specific for a single nucleotide (nt) variation.

The nature of introns 4-7 largely reflects the lineage specificity of HLA-A alleles.

For most HLA-A alleles the phylogeny of the 3' non-coding regions has not yet been studied systematically. In this study, we have determined the sequences of introns 4-7 in 50 HLA-A variants, and have computed nucleotide substitution rates and phylogenetic relationships. The A2/A28, A9, and A10 groups were characterized by clear lineage specificity.

Equivalent mobilization and collection of granulocytes for transfusion after administration of glycosylated G-CSF (3 microg/kg) plus dexamethasone versus glycosylated G-CSF (12 microg/kg) alone.

Background: The aim of this study was to find a regimen for mobilization and collection of granulocytes that combines low-dose G-CSF administration with satisfactory PMN mobilization and apheresis at a low rate of donor adverse reactions.

Study Design And Methods: In a prospective study, 52 healthy unrelated volunteers received a single subcutaneous injection of glycosylated G-CSF (Lenograstim Chugai-Pharma, Frankfurt, Germany) at medians of 3.1 (range, 2.

HLA-B*3531, a hybrid of B35 and B61, implications for diagnostic approaches to alleles with complex ancestral compositions.

The serological characterization of allelic variants that have been generated by large-scale interallelic recombination events indicates which residues may be involved in the formation of epitopes crucial for serological recognition. The allelic product of HLA-B*3531 is composed of B35 in its alpha1 domain and of B61(40) in its alpha2 domain. Both specificities are only weakly detectable with available sera.

HLA-B*4431: a new HLA-B variant with a complex ancestral history involving HLA-B*44, B*40 and B*07 alleles.

We here describe the identification of the new allele HLA-B*4431, which was found in three members of a Turkish family. Sequencing of the new allele following haplotype-specific PCR amplification revealed that exon 2 is identical to HLA-B*4402, whereas exon 3 resembles a HLA-B*40 variant with the exception of position 572, where a single nucleotide transversion (C > G) leads to an amino acid exchange (Trp162Ser). The generation of the 3' part of B*4431 may be best explained by a separate recombination between B*40 and B*07.

Sequence similarity matching: proposal of a structure-based rating system for bone marrow transplantation.

Recent advances in DNA-based typing have led to the detection of a continuously growing number of HLA alleles. For this reason, HLA matching in transplantation of hematopoietic stem cells from unrelated donors has become increasingly complicated. When there is no genotypically identical sibling and there are several alternative potential donors that all have a mismatch at a relevant HLA locus, until now no rating system has existed indicating different levels of allogenicity.

Non-expression of HLA-A*2901102 N is caused by a nucleotide exchange in the mRNA splicing site at the beginning of intron 4.

We describe the identification of the novel human leukocyte antigen (HLA) blank allele A*2901102 N which was detected in an individual of mixed race. The serological HLA class I typing was A1; B7,44 whereas PCR-SSP indicated the presence of an additional A*29 allele. The pedigree analysis demonstrated that the new blank allele segregated with the haplotype A*29null B*07, inherited from the individual's Vietnamese father.

A weak blood group A phenotype caused by a new mutation at the ABO locus.

Background: A number of alleles have been described for ABO encoding for common and rare ABO blood group phenotypes. Critical mutations in the coding sequence of ABO that may confer the different specificity and activity of the glycosyltransferases encoded by this gene locus have been identified.

Study Design And Methods: Three unrelated patients from Germany, Turkey, and Bosnia who were diagnosed as having variant A subgroups were subjected to extended ABO typing.

Loss of single HLA class I allospecificities in melanoma cells due to selective genomic abbreviations.

Expression of human leucocyte antigen (HLA) Class I molecules is essential for the recognition of malignant melanoma (MM) cells by CD8(+) T lymphocytes. A complete or partial loss of HLA Class I molecules is a potent strategy for MM cells to escape from immunosurveillance. In 2 out of 55 melanoma cell cultures we identified a complete phenotypic loss of HLA allospecificities.

The nucleotide diversity of MICA and MICB suggests the effect of overdominant selection.

The major histocompatibility complex (MHC) class I-related molecules A and B (MICA and MICB) are stress-inducible cell surface antigens that are recognized by immunocytes bearing the receptor NKG2D. In our study we estimated the average number of synonymous (pis) and nonsynonymous nucleotide substitutions (pia) per site in exons 2-4 of MICA and MICB. In exons 2 and 3 of MICB only nonsynonymous substitutions were found, and in exon 3 of MICA pia clearly exceeded pis.

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.

Second German consensus on immunogenetic donor search for allotransplantation of hematopoietic stem cells.

The present paper summarizes the results of the second German consensus meeting on immunogenetic donor search for allotransplantation of hematopoietic stem cells held in Essen in November 1999 under the auspices of the German Society for Immunogenetics (DGI) and the German Working Party for Blood and Marrow Transplantation (DAG-KBT). Immunogeneticists and transplant physicians from all over the country agreed to update the national standards for: (1) search strategy including the role of unrelated and extended family donor search after unsuccessful core family donor search, (2) histocompatibility loci to be typed, (3) histocompatibility typing techniques to be used (HLA serology vs DNA-based HLA typing, cellular tests, serum cross-match), and (4) acceptable HLA mismatches in the context of a defined underlying disease, donor type, and conditioning regimen.