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Biomedical subjects

G Lanzer

Publications and source records attributed to G Lanzer.

At least 19 recordsLinked to original sources
PubMed2002

Kell expression on myeloid progenitor cells.

Kell is one of the major human red blood cell groups and comprises 22 antigens. These antigens are produced by alleles located on chromosome 7, including sets of antithetical antigens such as Kell (K, K1) and cellano (k, K2), which differ in a single amino acid change (T193M). It consists of a 93-Kd transmembrane glycoprotein that is surface-exposed and shares sequence and structural homology with zinc endopeptidases, which are involved in regulating bioactive peptides. Anti-Kell antibodies have been shown to suppress fetal erythropoiesis. Recently published data indicate a similar effect on myeolopoiesis and megakaryopoiesis. Substantial thrombocytopenia in fetuses affected with HDN due to anti-K antibodies led to the discovery of the inhibitory effect of Kell-related antibodies on CFU-MK growth. In addition to its inhibitory effect on BFU-E growth, anti-Kell antibodies significantly reduced CFU-GM colony formation from haematologically normal individuals. Moreover, anti-cellano and anti-Kp(b) antibodies also inhibited the growth of CFU-GM from antigen positive MNC. These data indicate that Kell is not restricted to erythroid blood cells, but is expressed on a broader spectrum of haematopoietic cells than previously believed.

Autoantibodies↗
PubMed2001

A novel HLA-DRB1 sequence, DRB1*11272.

We describe the complete exon 2 sequence of a novel HLA-DRB1 allele, DRB1*11272. This allele differs from the DRB1*11271 allele by a synonymous mutation in codon 77 where an AAT is replaced with AAC, both encode for the amino acid asparagine. The same motif at codon 77 has also been found in DRB1*1107, DRB1*1333, DRB1*0422 and in most DRB1*03 alleles. A partial exon 2 sequence of this allele has previously been deposited in the EMBL Sequence Database under the accession number AF186407.

Alleles↗
PubMed2001

Kinetics of CFU-Mk after automated plateletpheresis.

BACKGROUND AND OBJECTIVES: Platelet count, thrombopoetin (TPO) level and the compartment of megakaryocyte progenitor cells (CFU-Mk) are major determinants in the regulation of thrombopoiesis. The aim of this study was to investigate the potential changes in the compartment of CFU-Mk and their correlation with serum TPO levels and platelet count after plateletpheresis. MATERIALS AND METHODS: Twelve healthy individuals were randomly assigned to undergo single-donor plateletpheresis. A collagen-based in vitro culture system was used to determine the number of peripheral blood (PB) CFU-Mk before and after donation and on days 1, 4 and 7 thereafter. TPO levels were measured by a specific enzyme-linked immunosorbent assay and whole blood counts were performed using an automated cell counter. RESULTS: The pre-apheresis platelet count (mean +/- SEM: 276 +/- 13 x 10(9)/l) decreased after plateletpheresis to a nadir of 194 +/- 8 x 10(9)/l (P < 0.001), showed a gradual increase on days 1 and 4, and reached pre-apheresis values by day 7 (280 +/- 11). The serum TPO levels were found to be significantly increased on days 1 and 7 as compared to baseline levels (baseline value 103.3 +/- 18.5 pg/ml versus day-1 value 135.8 +/- 25.8 pg/ml and day-7 value 132 +/- 30.19 pg/ml; P < 0.03 and P < 0.03, respectively). The numbers of CFU-Mk in PB were significantly elevated on day 4 only (125 +/- 21 colonies/ml of PB versus pre-apheresis values of 68 +/- 18 colonies/ml of PB, P < 0.005). CONCLUSIONS: These findings suggest that platelet loss during plateletpheresis affects thrombopoiesis at the progenitor cell level, probably through alterations in TPO plasma concentrations.

Blood Cell Count↗
PubMed2001

A new h allele detected in Europe has a missense mutationin alpha(1,2)-fucosyltransferase motif II.

BACKGROUND: The FUT1 gene encodes an alpha(1,2)-fucosyltransferase (H transferase), which determines the blood group H. Nonfunctional alleles of this gene, called h alleles and carrying loss-of-function mutations, are observed in the exceedingly rare Bombay phenotype. Twenty-three distinct h alleles have been characterized at the molecular level in various populations. The FUT2 (SE) gene is highly homologous to FUT1 (H:). STUDY DESIGN AND METHODS: The FUT1 gene of an Austrian proband with the Bombay phenotype was characterized by nucleotide sequencing of the full-length coding sequence. A PCR method using sequence-specific primers for FUT2 genotyping in whites was developed. The plasma alpha(1,2)-fucosyltransferase activity was determined. The distribution of the mutations underlying 24 h alleles and 7 se alleles was analyzed. RESULTS: The proband carried a new h allele. Two nucleotide changes, G785A and C786A, in codon 262 of the FUT1 gene resulted in the replacement of serine by lysine. No alpha(1,2)-fucosyltransferase activity was detected in the proband's plasma. The proband was homozygous for the seG428A allele. Six of 17 missense mutations in nonfunctional h and se alleles occurred in highly conserved fucosyltransferase motifs. No loss-of-function mutation was observed in the aminoterminal section encompassing the transmembraneous helix. CONCLUSION: The missense mutation S262K in the FUT1 gene caused the loss of H transferase activity. The analysis of the distribution of mutations in nonfunctional FUT1 and FUT2 genes can point to functionally important domains in the H transferase.

ABO Blood-Group System↗
PubMed2001

IL-10 increases the number of CFU-GM generated by ex vivo expansion of unmanipulated human MNCs and selected CD34+ cells.

BACKGROUND: Ex vivo expansion strategies with different cytokine combinations are currently used by several groups as a means of increasing the number of HPCs for a variety of special clinical applications. Because there is little information on the potential role of IL-10 in such ex vivo expansion models, the effect of this cytokine on the generation of myeloid progenitor cells in suspension cultures was investigated. STUDY DESIGN AND METHODS: On the basis of data from the literature and from new experiments, the combination of SCF and IL-3 at concentrations of 100 ng per mL and 100 U per mL, respectively, was chosen as the standard cocktail. The addition of IL-10 to such cultures resulted in a marked and dose-dependent potentiation of myeloid progenitor cell production. RESULTS: Using unmanipulated leukapheresis components from 13 individuals (including lymphoma and cancer patients and normal donors), the expansion multiple of CFU-GM after 14 days as compared with pre-expansion values was 9.54 +/- 2.31 times by SCF/IL-3 and 46.38 +/- 7.37 times by the combination of SCF/IL-3 and 100 ng per mL of IL-10 (p<0.001). IL-10 also potentiated CFU-GM generation from selected CD34 PBMNCs (n = 9) with an expansion of 17.22 +/- 7.04 times versus 45.67 +/- 16.78 times using the SCF/IL-3 and SCF/IL-3/IL-10 combination, respectively (p<0.05). Moreover, expansion-promoting effects of IL-10 were observed in liquid cultures containing MNCs from bone marrow (n = 4) and cord blood (n = 3), but did not reach statistical significance because of the small number of samples. CONCLUSION: These results suggest IL-10 as a useful cytokine to optimize progenitor cell-expansion strategies for clinical application.

Antigens, CD34↗
PubMed2000

Kell is not restricted to the erythropoietic lineage but is also expressed on myeloid progenitor cells.

Anti-Kell antibodies have been shown to suppress fetal erythropoiesis, but little is known about their effect on myelopoiesis. We analysed the effect of Kell-related antibodies on granulocyte-macrophage colony-forming units (CFU-GM) growth in semisolid medium using peripheral blood mononuclear cells (PBMNCs) from haematologically normal individuals. In addition to its inhibitory effect on erythroid burst-forming units (BFU-E) growth, anti-Kell antibodies significantly reduced CFU-GM colony formation from Kell-positive individuals but not from Kell-negative donors. Moreover, anti-cellano and anti-Kpb antibodies also inhibited the growth of CFU-GM from antigen-positive MNCs. These data indicate that Kell is not restricted to erythroid blood cells, but is also expressed on myeloid progenitor cells.

Antibodies↗
PubMed2000

Severe HDN due to anti-Ce that required exchange tranfusion.

BACKGROUND: Rh system antibodies are commonly encountered in blood bank practice as well as during pregnancy. Nevertheless, no examples of anti-Ce (RH7) have been reported as a cause of HDN that requires exchange transfusion. CASE REPORT: A 38-year-old woman in her fourth pregnancy was typed as blood group O D+, C-, c+, E+, e-. Anti-C and anti-e were detected in her serum during a routine prenatal work-up. Further evaluation, including flow cytometric analysis, revealed the presence of a strong anti-Ce and a weak anti-e. Her partner was typed as group A D+, C+, c-, E-, e+. A seemingly healthy male infant was delivered at 40 weeks of gestation. The infant's RBCs were typed as group O D-, C+, c+, E+, e+ with a positive DAT (titer 128). Twenty-five hours after birth, the baby had to be transferred to the neonatal intensive care unit because of rapidly rising total serum bilirubin. Despite intensive treatment, including double phototherapy, albumin infusion, and the administration of furosemide and IVIG, the total serum bilirubin level increased during the following day and exchange transfusion with 2 units of type O D-, C-, c+, E+, e- had to be performed; this resulted in a prompt decrease in total serum bilirubin without relapse. CONCLUSION: Anti-Ce caused severe HDN requiring exchange transfusion. This highlights the need for a close follow-up throughout pregnancy if unexpected RBC antibodies are present, to permit the provision of compatible blood in case of a rare antibody.

Adult↗
PubMed1999

Virtual DNA analysis as a platform for interlaboratory data exchange of HLA DNA typing results.

In 1998, the German DNA Exchange offered the possibility to report typing data as virtual DNA. Participating labs have been equipped with software based on the principle of Virtual DNA Analysis (VDA). This approach allows the combination of sequence-specific oligonucleotide (SSO), sequence-specific primer (SSP) and sequence-based typing (SBT) results. The use of all types of test kits has been allowed without any limitations, as long as basic sequence information on SSOs or SSPs was available, at least the sequence and the position of the detected motif on the sample DNA. Typing raw data of the actual SSO-SSP and, if performed, SBT information was collected. Participating labs received 20 DNA samples to type. Fourteen labs returned data on 1,250 single-locus testings. Reported data consisted of 317 SBT data, 452 SSO kits and 1,795 SSP kits with 43,312 single SSO/ SSP reactivities. One hundred and twenty-six different typing kits (unique laboratory-specific kits, commercial kits from 7 companies) have been used. In 30 (2.4%) single-locus testings, at least one single SSO/SSP reactivity has been false-positive or -negative, thus not leading to a valid result on primary evaluation. Eight of these 30 cases were due to the presence of a new DRB1*14 allele in sample no. 2. Thirty-five tests (2.8%) showed wrong allele assignments. This first attempt to collect raw typing data instead of typing interpretation on a larger scale shows the advantages of Virtual DNA Analysis like interlaboratory data exchange without loss of information, transparency of typing interpretation and reinterpretation of typing data with an updated allele database. The VDA format is a useful tool for workshops and bone marrow donor registries.

Alleles↗
PubMed1998

HLA-B*27 typing by group-specific hybridization in microtiter plates.

We have developed and evaluated a test for HLA-B*27 based on PCR and DNA hybridization in microtiter plates. A region within exon 2 of the HLA-B gene is amplified and labeled by PCR and the amplification product is hybridized to a group-specific HLA-B*27 and a generic control oligonucleotide probe in two separate cavities of the plate. Bound sequences are detected using an ELISA-like protocol. The assay has been evaluated on 254 DNA samples routinely received for B27 testing in parallel with serological and SSP-PCR typing. Results were concordant in typing 102 HLA-B27-positive and 152 HLA-B27-negative individuals except for two samples containing HLA-B*73, which stained B27 positive in the microwell test. The new procedure is rapid and simple to perform, and the microwell format is particularly suitable for automation.

Enzyme-Linked Immunosorbent Assay↗
PubMed1998

Virtual DNA analysis--a new tool for combination and standardised evaluation of SSO, SSP and sequencing-based typing results.

In order to obtain reliable information on HLA types, DNA typing with sequence-specific oligonucleotide/primer (SSO/SSP) typing sets or sequencing-based typing (SBT) is increasingly performed. The quality of the evaluation depends on the presence of a complete listing of all typed alleles as well as on the ability of detecting all corresponding alleles/allele pairs. We have developed the concept of virtual DNA analysis (VDA), which is able to combine all types of SSO/SSP/SBT results and evaluate this typing in combination according to the latest published allele sequence lists. The concept is based on the target DNA recognised by the respective typing techniques. All SSO/SSP or SBT results are transformed to a virtual sample DNA, which subsequently is analysed. Evaluation of generic or allele-specific DNA typing or the combination of both is supported. Due to this flexible approach, all kinds of SSO/SSP sets, as far as the respective SSO/SSP sequences are available, can be entered and evaluated immediately. The combination of collected data of different typing sets and procedures leads to the highest possible typing resolution. If more than one possible allele combination persists, the program reduces the result to the most specific common denominator in a stepwise manner. VDA offers the possibility of re-evaluation of former SSO/SSP/SBT results, alone or in combination. No solutions are omitted. This might be a first step towards standardisation of evaluating DNA-based HLA typing results or transfer of the respective typing data for later evaluation.

Databases, Factual↗
PubMed1998

The determination of metabolite M17 and its meaning for immunosuppressive cyclosporin therapy.

Cyclosporin A (CyA) is intensively metabolized by the hepatic cytochrome p450 III monooxygenase A system in the human liver, the most important metabolites being M1, M17, and M21. Because CyA and its metabolites have nephrotoxic, hepatotoxic, and neurotoxic side effects, CyA dosage must be calculated to avoid the risk of organ rejection through underdosage and toxic organ damage through overdosage or accumulation of metabolites. In this study, we determined the whole-blood concentrations of cyclosporin and metabolite M17 by high-pressure liquid chromatography (HPLC) and by monoclonal specific and polyclonal nonspecific fluorescence polarization immunoassay (Abbott) in patients after immunosuppressive treatment. Patients with different resorption and metabolization rates showed high individual variations. CyA concentrations in patients with good liver function and low concentrations of CyA metabolites showed a good correlation between the HPLC and the FPIA (TDx-monoclonal assay) methods in ranges between 25 and 180 ng/mL. TDx-monoclonal was not always as precise as HPLC. In cases of metabolic disorders, we found false high CyA concentrations assayed with the immunologic method, caused by a crossreaction of the elevated metabolite concentration. We found that HPLC rendered more information about the extent of immunosuppressive activity and the metabolization rate and showed a good correlation with the concentration of metabolite M17 and total metabolites measured with the Abbott CyA polyclonal kit.

Antibodies↗
PubMed1997

Detection and differentiation of platelet-specific antibodies by flow cytometry: the bead-mediated platelet assay.

BACKGROUND: Platelet-reactive antibodies cause a number of clinical disorders. The detection and differentiation of these antibodies are prerequisites for the adequate treatment of these disorders. The bead-mediated platelet assay described here enables the detection and differentiation of platelet-bound antibodies by the use of flow cytometry. STUDY DESIGN AND METHODS: The bead-mediated platelet assay is based on the isolation of human platelet glycoproteins by using flow cytometric standardization beads after the incubation of typed platelets with human sera. The specificity and sensitivity of this assay were tested with five sera, each containing a known platelet-reactive antibody. The monoclonal antibody-specific immobilization of platelet antigens assay was used as a reference test. RESULTS: The bead-mediated platelet assay was able to determine the glycoprotein specificity of the antibody without cross-reactions in every case. In serial dilution tests, the bead-mediated platelet assay was able to detect the antibodies at higher dilutions than the monoclonal antibody-specific immobilization of platelet antigen assay. Total test time was 3.5 hours. CONCLUSION: The bead-mediated platelet assay is a fast and reliable method for the detection and differentiation of platelet-reactive antibodies.

Antibodies, Monoclonal↗
PubMed1996

[Autologous blood donation with preliminary erythropoietin stimulation].

Low basal hemoglobin and functional iron deficiency are the limiting factors in autologous blood donation program. Treatment with recombinant human erythropoietin can increase the volume of autologous blood and makes donation of > or = 3 units possible-even in patients with low basal hemoglobin. Best results are obtained if stimulation begins already one week before first donation.

Anemia, Iron-Deficiency↗
PubMed1996

[Computer-assisted evaluation of a "medium resolution" HLA-DRB oligotyping of bone marrow donors].

One drawback of a 'medium resolution' generic dotblot oligonucleotide typing of the HLA-DRB locus has been the time consuming evaluation of the collected SSO-hybridisation datas. We developed a program on the basis of MS-ACCESS, written in visual basic, called HIDE (HLA Intelligent Data Evaluation) to manage this problem. HIDE offers a complete data management for the donor and the incoming sample, supports a membrane based data entry of the hybridisation-reactions and multiple testing of a sample. If an evaluation shows more than one matching allele combination, the result is summarized according to the main DRB-groups. The flexible structure of the program allows the entry of additional allelspecific reaction-patterns as well as the adaption to different SSO-typingsets.

Alleles↗
PubMed1995

[Therapeutic concepts in transfusion medicine. Report on the 1st Graz "Transfusion Medicine" Consensus Conference].

The safety of blood and blood components is an important aspect of transfusion medicine. Even if absolute safety of blood products cannot be achieved, this goal has come closer due to significant improvements. These include: (1) exact donor registration; (2) component preparation according to legal requirements and GMP guidelines; (3) determination of all relevant diagnostic parameters according to GMP/GLP guidelines; (4) adequate storage of products; and (5) and often underestimated parameter ensuring safety, strict guidelines for the use of blood products in the treatment of patients. Some of the results of the first Graz Consensus Conference on Transfusion Medicine are presented.

Austria↗