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A Poschmann

Publications and source records attributed to A Poschmann.

At least 19 recordsLinked to original sources
PubMed1997

Monoclonal antibodies for the detection of desialylation of erythrocyte membranes during haemolytic disease and haemolytic uraemic syndrome caused by the in vivo action of microbial neuraminidase.

Especially in childhood, the in vivo action of microbial neuraminidase may cause haemolytic anaemia or life-threatening haemolytic uraemic syndrome. The exposure of the Thomsen-Friedenreich (T) crypto-antigen and T-antigen polyagglutinability of erythrocytes has been described as the first sign of toxic cleavage of N-acetylneuraminic acid (Neu5Ac) from sialoglycoproteins of cell membranes. This phenomenon may, however, be too unspecific to initiate treatment for toxin elimination. The present study investigated the diagnostic effectiveness of a panel of three monoclonal antibodies (mcabs) for the estimation of the clinical significance of neuraminidase action in vivo. Depending on the amount of Neu5Ac released, the mcabs I-C4, II-Q9 and III-Y12 recognized different epitopes on erythrocyte asialoglycophorin. In 1345 patients, the mcab II-09 detected cleavage of Neu5Ac in 32 children who had T-antigen polyagglutinability and mild to moderate haemolytic anaemia. However, only 10 patients, whose erythrocytes were agglutinated by the mcabs III-Y12 or I-C4, developed severe haemolysis, thrombocytopenia, and finally the life-threatening haemolytic uraemic syndrome (p<0.0002). In conclusion, these mcabs provided an early marker of the in vivo action of neuraminidase. Two different degrees of erythrocyte desialylation, as defined by these mcabs, are suggested to reflect the severity of toxin-associated disease.

Anemia, Hemolytic↗
PubMed1995

[Flow cytometry detection of erythrocyte antigens and antibodies. Technical aspects and new clinical applications].

BACKGROUND: Although hemagglutination techniques have proved worthwhile since many years in immunohematology, they also have several disadvantages. They are manual and subjective visual methods, which make it difficult to quantitate red cell antibodies or surface antigens. Flow cytometric analysis overcomes these limitations because of its ability to analyze individual populations of cells by sensitive, reproducible, and objective methods. MATERIALS AND METHODS: Washed red cells from regular blood donors and patients were analyzed natively and after treatment with enzymes (sialidase, protease) or pneumococcal polysaccharides, using monoclonal Rh antibodies, human 7s-immunoglobulin, and FITC-labeled anti-human IgG or FITC anti-T lectin. The fluorescence intensity of single red cells was determined in the Ortho Cytoron Absolute flow cytometer. RESULTS: We determined the optimal test conditions and normal values by investigation of 50 blood donors. The fluorescence intensity of untreated red cells proved to be constant and therefore was used to adjust the instrument. Furthermore, the data of experimental adsorptions of red cells with pneumococcal antigens, sialidase (Vibrio cholerae) and protease (papain) as well as data from patients suffering from chronic HBV infection and autoimmune hemolytic anemia and acute pancreatitis are presented. A special software program was developed for statistical analysis and graphical presentation of the raw data. The computer program permits to analyze results from different experiments or from different dates and depicts them comparatively in overlay histograms, which may be useful in a serial study of changes of the antibody concentration or antigen expression. CONCLUSION: The flow cytometric analysis of red cells proves to be a simple, rapid, reproducible, and objective method for antigen and antibody quantitation. Furthermore, this technique may be a useful new tool for the investigation of acute, infection-associated hemolytic anemia.

Acute Disease↗
PubMed1992

Results of the DGTI workshop on the evaluation of the reactivity of monoclonal anti-D.

All D+ samples were detected by all monoclonal antibodies without problems. Very few of the 3000 D- samples showed a +/- to ++ reaction with some of the IgG type mabs using the Coombs technique. It is still open whether these are specific reactions with weak positive samples, which were negative with polyclonal sera. IgM type mabs detected up to 100% of the Du samples dependent on the Rh-phenotype and the technique used (CCDuee greater than CcDuee greater than ccDuEe). Most of the CCDuee samples reacted very strong and should no longer be regarded as Du.

Antibodies, Monoclonal↗
PubMed1992

Results of the DGTI workshop on the evaluation of the reactivity of monoclonal anti-D.

All D+ samples were detected by all monoclonal antibodies (mabs) without any problem. Very few of the 3,000 D- samples showed a +/- to ++ reaction with some of the IgG type mabs using the Coombs technique. It is still open whether these are specific reactions with weakly positive samples, which were negative with polyclonal sera. IgM type mabs detected up to 100% of the Du samples dependent on the Rh phenotype and the technique used (CCDuee > CcDuee > ccDuEe). Most of the CCDuee samples reacted very strongly and should no longer be regarded as Du.

Antibodies, Monoclonal↗
PubMed1992

[New possibilities in diagnosing hemolytic disease of newborn infants].

The diagnosis and management of HDN relies on measurement of maternal anti-D, amniotic fluid analysis and fetal blood sampling by chordiocentesis. However, amniocentesis and chordiocentesis have substantial risks of fetomaternal hemorrhage and subsequent increase in maternal anti-D. In addition to quantitation the functional activity of maternal anti-D has been determined by measuring the interaction of red blood cells sensitized by maternal serum in monocyte-monolayer assays. We assessed the functional activity of anti-D by titration of the sensitized red blood cells using selected sera with rheumatoid factor (RF) as human anti-IgG. First experiments using monoclonal anti-D showed a good correlation between erythrophagocytosis and RF titers. The bilirubin-protein ratio in amniotic fluid may be of great value in predicting the severity of HDN, as shown in 94 cases with severe and 39 cases with moderate disease. Amniotic fluid analysis is complicated by the presence of hemoglobin; we developed a computer program to solve this problem. To improve the serological diagnosis of ABO incompatibility, we measured IgG-anti-A, B in 1,392 maternal and newborn sera applying a sensitive gel test with Coombs serum. Furthermore, we determined the hemolytic activity of anti-A, B by microscopic observation of the morphological changes of red blood cells.

Blood Transfusion, Intrauterine↗
PubMed1992

[Kinetic measurement of GPT with the microtiter plate].

Experiences with a kinetic method for measurement of SGPT in microtiter plate using an automatic sample processing device and Medusa software (Biotest) were evaluated. The correlation coefficient in parallel assessment of samples in a clinical routine laboratory was found to be 0.935 (p < 0.0001). The correlation coefficient comparing the internal standard dilution with actual recordings was found to be 0.999 (p < 0.0001). Automated screening of SGPT in microtiter plates seems thus to be reliable as well as feasible in blood bank routine.

Alanine Transaminase↗
PubMed1992

[New possibilities in diagnosis of hemolytic diseases in newborns].

The diagnosis and management of the hemolytic disease of the newborn (HDN) rely on measurement of maternal anti-D, amniotic fluid analysis, and fetal blood sampling by cordocentesis. However, amniocentesis and cordocentesis have substantial risks of fetomaternal hemorrhage and subsequent increase in maternal anti-D potency. In addition to quantitation, the functional activity of maternal anti-D has been determined by measuring the interaction of red blood cells sensitized by maternal serum in monocyte-monolayer assays. We assessed the functional activity of anti-D by titration of the sensitized red blood cells using selected sera with rheumatoid factor (RF) as human anti-IgG. First experiments using monoclonal anti-D showed a good correlation between erythrophagocytosis and RF titers. The bilirubin/protein ratio in amniotic fluid may be of great value in predicting the severity of HDN, as shown in 94 cases with severe and 39 cases with moderate disease. Amniotic fluid analysis is complicated by the presence of hemoglobin; we developed a computer program to solve this problem. To improve the serological diagnosis of ABO incompatibility, we measured IgG-anti-A,B in 1,392 maternal and newborn sera applying a sensitive gel test with Coombs serum. Furthermore, we determined the hemolytic activity of anti-A,B by microscopic observation of the morphological changes of red blood cells.

ABO Blood-Group System↗
PubMed1991

[Preliminary results of the DGTI Workshop for evaluating the reactivity of monoclonal anti-D].

Within a working group of the German transfusion society, a workshop was conducted to evaluate the reactivity of monoclonal anti-D supernatants. During this evaluation 10,000 samples were tested, including 325 Du-samples, with 3-5 IgM type antibodies and 3-4 IgG type antibodies, which were selected to also find 'D-variants'. In general, the reactivity with D+ red blood cells was good, and specific in respect to D negative samples. Some samples have been found to have a different pattern of reactivity than the monoclonal antibodies used. Dependent on the method and on the antibody, in some studies up to 100% of Du samples could be detected by anti-D of the IgM type. Some data indicate that the reaction with Du samples is not dependent on titer. In addition, in separate studies the data show a correlation of reactivity in respect to the Rh-phenotype (CcDuee greater than ccDuEe).

Antibodies, Monoclonal↗
PubMed1990

Solid-phase antiglobulin test for screening and identification of red cell antibodies.

A newly developed automatically readable solid-phase antiglobulin test is described. The solid-phase test in comparison with conventional antiglobulin techniques for screening and identification of red cell antibodies showed agreement in 2346 (98.7%) of samples tested. The increased sensitivity of the solid-phase antiglobulin test is demonstrated by examination of serial twofold dilutions of antibodies.

Autoanalysis↗
PubMed1990

[The "Eilbek capillary"--a new immune hematologic technic].

Studying RBC sedimentation in hematocrit capillaries filled with a variety of separation media (Sephacryl S-300, Ultrogel AcA22 and others) and spinned down for a short time we found some striking advantages in comparison to standard hemagglutination techniques. The scope of diagnostic procedures may be improved and broadened as far as anemias caused by autoantibodies and infections as well as hemolytic disease of the newborn--especially AB0-erythroblastosis--and pretransfusion testing are concerned.

ABO Blood-Group System↗
PubMed1989

High-frequency antigens of human erythrocyte membrane sialoglycoproteins. VI. Monoclonal antibodies reacting with the N-terminal domain of glycophorin C.

The epitopes of seven mouse monoclonal antibodies which are related to the Gerbich blood group system were investigated. BRIC4, BRIC10, GERO and MR4-130 have been published earlier. The three others (APO1, APO2, APO3) were prepared by immunization with normal human erythrocytes and detected by screening with red blood cells that lack glycophorins C and D. Using immunoblotting and hemagglutination inhibition assays, the epitopes for all antibodies were found to be located on glycophorin C. Hemagglutination inhibition experiments with peptides and chemically modified glycophorins revealed that MR4-130, GERO, BRIC10 and APO2 are all directed against identical or rather similar epitopes comprising the N-terminal three or four residues of glycophorin C. Modification of the N-terminal methionine residue or release of sialic acid attached to oligosaccharide(s) at the third and/or fourth position(s) destroyed all these antigens. The epitope of APO3 was found to comprise glutamic acid17 and/or aspartic acid19 as well as the oligosaccharide attached to serine15. The antigens of BRIC4 and APO1 were found to be located within the residues 2-21 and to comprise sialic acid attached to O-glycosidically linked oligosaccharide(s). However, these epitopes could not be elucidated further. Radio-iodinated MR4-130 bound to 39,000 receptor sites per normal red blood cell. Binding of the labelled antibody was completely inhibited by unlabelled MR4-130, BRIC10, APO2 and GERO. APO1 caused partial inhibition suggesting that it is directed against an adjacent site. BRIC4, APO3 and anti-Ge3 did not inhibit the binding of labelled MR4-130 to any significant extent.

Antibodies, Monoclonal↗
PubMed1987

Computer-aided hybridoma screening. Production of monoclonal antibodies against membrane fractions from mammary tumour tissue.

Monoclonal antibodies were raised against membrane fractions from mammary tumour tissue. 746 hybridomas were obtained against the so-called membrane fraction '2a' and 1393 hybridomas against the so-called 'top-region'. These hybridomas were tested with an immunodot assay, cell-binding radioimmunoassay and an immunocytological screening assay using several antigens. In the evaluation of these data we used the common database software (dBASE II) on a personal computer. To facilitate computer handling, even for the non-specialist, we programmed our individual menu-driven software for computer-aided hybridoma screening.

Animals↗
PubMed1987

Screening of hybridoma supernatants raised against membrane fractions from breast cancer using an immunodot assay.

Membranes were prepared from mammary tumors and fractionized using gel filtration and gradient polyacrylamide gel electrophoresis. To obtain monoclonal antibodies against tumor-associated antigens, mice were immunized against membrane fraction 2a. After hybridization, we obtained 746 hybridoma cell lines. We performed the immunodot assay for screening. Every supernatant was tested against 15 antigens. Eight antigens were purified fractions from tumor membrane preparation, and five were crude membrane preparations from benign and malignant breast cell lines. Additionally, the Thomsen-Friedenreich antigen of erythrocytes was tested. We selected 83 hybridomas for further characterization.

Animals↗