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J Neppert

Publications and source records attributed to J Neppert.

At least 37 records · Page 2Linked to original sources
PubMed1997

Linkage disequilibria between Duffy blood groups, Fc gamma IIa and Fc gamma IIIb allotypes.

Fc gamma receptors (Fc gamma R) on white blood cells and the Duffy blood group antigens on red blood cells are coded for on the long arm of chromosome 1. They appear in different allotypic forms: the high responder/low responder (HR/LR) forms of Fc gamma RIIa, the alloantigens NA1 and NA2 of Fc gamma RIIIb and the Duffy blood group antigens Fya and Fyb. The aim of this study was to analyze possible linkage disequilibria between these allotypic immunomodulatory receptors, and thus provide evidence for the existence of a hypothetical gene complex. The Duffy phenotype was determined by the indirect antiglobulin test, NA1/NA2 phenotypes by the granulocyte agglutination test and the HR/LR polymorphism by an immunophagocytosis assay. Two haplotypes were found to be in linkage disequilibrium. For the haplotype NA2, Fyb we calculated a delta-value of -0.07 and for the haplotype NA1, HR we obtained a delta-value of -0.02.

Antigens, CD↗
PubMed1996

Antibodies to human major histocompatibility complex products inhibit Fc gamma receptors types I and II.

We have analysed the effect of polyclonal and monoclonal antibodies of distinct IgG isotypes directed against products of the human major histocompatibility complex (MHC) on the function of Fc gamma receptors types I (Fc gamma RI) and II (Fc gamma RII). Human anti-D sensitized red blood cells (RBC), selectively binding to Fc gamma RI, and bovine or murine IgG1 (bIgG1 or mIgG1) sensitized RBC, selectively binding to Fc gamma RII, were employed as targets for the effector cell in order to distinguish the inhibition of both types. Using these targets it could be shown that human antibodies to products of the human MHC or murine monoclonal antibodies with the same specificity and mIgG2a isotype inhibited both the Fc gamma RI-and the Fc gamma RII-mediated function. In contrast, murine monoclonal antibodies with the same specificity but of the mIgG1 isotype only inhibited the Fc gamma RII-mediated function. In a control experiment, human and murine antibodies to products of the MHC did not impair the Fc gamma R-independent phagocytosis of Saccharomyces by monocytes and neutrophils. The present study suggests that this mechanism involves at least two different Fc gamma receptors.

Animals↗
PubMed1996

Can blood group O red cells of donor origin acquire weak group A reactivity through serum A transferase of the recipient after bone marrow transplantation?

BACKGROUND: Blood group A substance was detected on red cells of a patient who received a bone marrow transplant from a blood group O donor 3.5 years ago. MATERIALS AND METHODS: Peripheral blood was investigated by conventional serological techniques, fluorescence in situ hybridisation, and polymerase chain reaction. RESULTS: All peripheral blood cells are of donor origin. Anti-A and not anti-A, B of blood group O individuals can be absorbed to the group O red cells of the patient. CONCLUSION: We suppose that the patient's residual serum A transferase attaches the appropriate sugar to substance H on the red cell membrane to form substance A.

ABO Blood-Group System↗
PubMed1995

Biotinylation: a nonradioactive method for the identification of cell surface antigens in immunoprecipitates.

A nonradioactive method was employed to detect different cell membrane antigens on human polymorphonuclear granulocytes, monocytes and platelets. We compared the reactivity of one monoclonal antibody, N1III10, assumed to be Fc gamma RII-specific by functional assays, with other well-characterized monoclonal antibodies and human sera. Intact cells were incubated with biotin N-hydroxysulfosuccinimide ester which preferentially reacts with lysine residues in polypeptides. Biotin-labeled cells were lysed and the antigen was isolated from the cell lysate by immunoprecipitation with the antibody bound to Protein A-Sepharose. The precipitates were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, transferred onto nitrocellulose membrane, and visualized by a streptavidin-alkaline phosphatase system with a suitable substrate. Using this biotin-labeling system we could show that N1III10 detects a 40 kDa antigen on monocytes and platelets, comparable to that expected of Fc gamma RII monoclonal antibodies.

Alkaline Phosphatase↗
PubMed1995

Mild course of fetal RhD haemolytic disease due to maternal alloimmunisation to paternal HLA class I and II antigens.

The patient is a pregnant women of African origin with a prior history of spontaneous abortion and newborn dystrophy. The investigation showed an anti-Rh D antibody (IgG isotypes 1 and 3) with an indirect antiglobulin tube test (IAT) titre of 1:512. The monocyte monolayer assay (MMA) proved clearly the interaction of Fc receptors with the maternal anti-D, and so a clinical significance was expected. In spite of this, no signs of severe haemolysis in the Rh-D-positive and direct antiglobulin test-positive fetus could be observed. Furthermore, two HLA class I and II alloantibodies (anti-A10, anti-DR13) directed against paternal and fetal antigens were detected in the serum of the gravida. Both antibodies showed an inhibitory effect on the in vitro phagocytosis capacity of mononuclear cells expressing at least one of the corresponding HLA antigens (immunophagocytosis inhibition (IPI) test). Thus, the mild course of haemolytic disease may be explained by an effective inhibition of the fetal mononuclear phagocyte system by maternal HLA class I and/or class II antibodies resulting in a diminished destruction of anti-D-coated fetal red blood cells.

Adult↗
PubMed1994

Immunogenetic and serological investigations in nonpregnant and in pregnant women with a history of recurrent spontaneous abortions. German RSA/IVIG Study Group.

In the context of a controlled multicenter study on intravenous immunoglobulin (IVIG) treatment of patients with a history of unexplained recurrent spontaneous abortions (RSA), a number of controversial immunological parameters were evaluated prior to and during pregnancy with respect to their diagnostic and/or prognostic significance. A total of 390 serum samples from 52 patients were investigated. Sharing of 2 or more HLA (A, B, DR, DQ) antigens was significantly more frequent in RSA couples than in controls. The rate of cytotoxic or Fc-receptor (FcR)-blocking antibodies was not significantly lower in RSA patients than in individuals with normal pregnancies. Both tumor necrosis factor-alpha (TNF-alpha) levels and IgG anticardiolipin antibodies (IgG-ACA) were significantly increased in the patient group. While the occurrence of HLA sharing, cytotoxic/FcR-blocking antibodies and IgG-ACA did not correlate with the outcome of pregnancy, TNF-alpha levels were found to be significantly higher in patients with subsequent miscarriage than in those with successful pregnancy. IgG-ACA, if present, significantly decreased during the course of successful pregnancy but remained high in patients with subsequent abortion. It is concluded that the diagnostic and/or prognostic value of HLA sharing and cytotoxic/FcR-blocking antibodies has been overestimated while TNF-alpha and ACA levels are potential diagnostic markers and/or exhibit prognostic significance in subgroups of RSA patients.

Abortion, Habitual↗
PubMed1994

Circulatory clearance of transfused antibody-sensitized red cells in an entirely allogenic rabbit model.

BACKGROUND: Antibodies against histocompatibility antigens on phagocytes abrogate their Fc gamma-receptor-mediated functions in vitro. Studies were carried out to determine whether this phenomenon also exists in vivo. METHODS: An allogenic blood group antibody was generated in rabbits. Red cells sensitized with this antibody were internalized in vitro by rabbit phagocytes. Another allogenic antibody specific for major histocompatibility complex (MHC) antigens of rabbits was produced. Plasma containing this antibody was infused into rabbits with phagocytes expressing the corresponding MHC antigens. Thereafter, the sensitized rabbit red blood cells were transfused into the rabbits. RESULTS: The following 3 phases of the circulatory clearance of transfused sensitized red cells could be observed when MHC antibodies were not given prior to the transfusion: 1. initial rapid clearance of the cells (t/2 = 1.7-3.3 min), 2. release of the cells back into the circulation after 0.5-24 h and 3. terminal slow clearance which was, however, faster than that with unsensitized cells. Two independent experiments carried out on the same recipient out of the 3 recipients analysed showed that the prior treatment of the recipient with MHC-alloantibodies extended the circulatory half-life of the sensitized red cells during the terminal phase from t/2 = 1 day to t/2 = 3 and 4 days, respectively. CONCLUSION: Antibodies against MHC antigens on phagocytes can reduce the Fc gamma-receptor-mediated immune elimination of sensitized red cells. This corresponds to the observation that many cases of morbus haemolyticus neonatorum show unexpectedly reduced levels of foetal red cell destruction and a good clinical outcome if mothers not only produce antibodies to Rh (D) but also to foetal MHC antigens.

Animals↗
PubMed1994

Can blood group O red cells of donor origin acquire weak group A reactivity through serum A transferase of the recipient after bone marrow transplantation?

Blood group A substance was detected on red cells of a patient who had received a bone marrow transplant from a blood group 0 donor 3 1/2 years ago. All peripheral blood cells are of donor origin. Anti-A but not anti-A,B of blood group 0 individuals can be absorbed to the group 0 red cells of the patient. We suppose that the patient's residual serum A transferase attaches the appropriate sugar to H substance on the red cell membrane to form A substance.

ABO Blood-Group System↗
PubMed1993

[Washing and filtration of blood components: which indications are established?].

The washing of cells in blood components for transfusion is necessary (1) in cases of severe incompatibility to constituents of plasma in these components and (2) in cases of maternal antibodies to blood cells of the child when the child needs maternal blood components, e.g. in many cases of neonatal alloimmune thrombocytopenia. A single washing step is recommended in certain cases: paroxysmal nocturnal hemoglobinuria and T activation of red blood cells. There is no indication that components should be washed in cases of autoimmune hemolytic anemia. There are well-documented data which propound the necessity of filtering blood components in order to reduce the leukocyte content aiming at the prevention of a primary immune response to HLA antigens, of repeated febrile transfusion reactions caused by leukocyte antibodies and of the transmission of cytomegalovirus via blood components. Some observations suggest that the same type of filtration also should be carried out on blood components given to patients with paroxysmal nocturnal hemoglobinuria.

Blood Component Transfusion↗
PubMed1992

[Procedure for production of leukocyte depleted erythrocyte and thrombocyte concentrates (PRP method) using top and bottom bags, Optipress automated separators and a computer controlled Cryofuge 6000].

PRP methods for production of WBC-poor red blood cell (RBCC) and platelet concentrates (PC) are investigated using top-and-bottom bags and Optipress separators. A standard centrifugation method (profile A) and 2 methods (profiles B and C) for a computer run centrifugation using 21 (profile B) or 19 (profile C) varying time segments and g numbers. An MS-DOS-compatible personal computer runs a Cryofuge 6000. 500 ml fresh whole blood are collected in triple and/or quadruple top-and-bottom blood bags. Samples of 163 blood donors, 163 RBCCs and 161 PCs are analyzed by a Coulter Counter T 540. Blood smears of 5 RBCCs made by profile B are evaluated. Mean WBC contamination of RBCCs produced by profiles A, B and C is found to be lower than 5 x 10(8)/RBCC. None of the 5 blood smears can be counted out completely. The full number of 100 WBCs is not detected. All WBCs found are polymorphous nuclear cells. Mononuclear cells (MNC) are not evident. PCs produced by profile B contain a mean platelet yield of (76.4 +/- 21.2) x 10(9)/PC and a WBC contamination of (1.2 +/- 0.7) x 10(7)/PC. The PCs of profile B differ significantly (p < 0.001) from those of profile A and profile C. The results show a high quality of RBCC and PC produced by PRP methods using top-and-bottom blood bags and Optipress separators. Employing a computer run centrifuge, PC and RBCC contain a similar WBC contamination compared with concentrates produced by buffy coat methods.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Component Removal↗
PubMed1992

[High precision, reproducibility and practical application of modified alanine aminotransferase determination with the microtiter plate].

In order to improve the alanine aminotransferase (ALT) assay by using microtiter plates, a new 96-channel multiple syringe of high precision and incubation chambers with precise regulation of the temperature operated by computer were developed. In accordance with the recommendation of the German Society of Clinical Chemistry for the optimized standard method, the ALT assay was modified for the procedure at 25 degrees C. The modification was comparable with the best conventional methods which, however, are very time-consuming. The ALT assay has the advantages of the microtiter plate, e.g., secure sample identification, on-line documentation and reduction of costs and time for the analysis.

Alanine Transaminase↗
PubMed1991

Alloantiserum recognizing a DQw2 split which is associated with DR3.

A typing serum MUE 38539 II, was found to recognize a DR3-associated split of DQw2. In cytotoxicity tests, MUE 38539 II yielded positive test results with B lymphocytes but not with monocytes of DR3-positive cell donors. This was in contrast to other typing reagents for DR3 that react with B lymphocytes as well as monocytes. Lymphocytotoxicity tests using MUE 38539 II were negative with DR7- and DQw2-positive cells. The assumption that the serum recognizes a DR3-associated split of DQw2, and not DR3 itself, was confirmed by the lack of reactivity with a DQw4- and DR3-positive lymphoblastoid cell line (RSH). The assumption was also corroborated using reagents from a family in which DR3 and DQw2 were not found in the usually described linkage. In two lines, DR3 was associated with DQw- (2707 and 2710), and in the cell line 2704, DQw2 was associated with DRw-. The serum MUE 38539 II was exclusively cytotoxic with lymphoblastoid cell lines from those family members who were positive for DQw2, independently of the DR3 antigens of the cells.

Cytotoxicity Tests, Immunologic↗
PubMed1991

Human leukoagglutinating antibody evokes cooperative leukotriene synthesis in pulmonary microvasculature. Model of transfusion-related acute lung injury.

Leukoagglutinating antibodies have been implicated in the development of transfusion-related acute lung injury. In the present study, human neutrophil leukotriene generation was provoked by an anti-5b immunoglobulin G, isolated from a multiparous donor plasma that caused noncardiogenic lung edema during transfusion therapy. In 5b-positive polymorphonuclear neutrophils (PMNs), the antibody stimulated marked arachidonic acid metabolism, dependent on the presence of plasma as the complement source. Quantity and profile of lipid mediators (leukotriene B4 and its omega-oxidation products, 5-hydroxyeicosatetraenoic acid, and nonenzymatic hydrolysis products of leukotriene A4) corresponded to those repeatedly described after PMN in vitro stimulation with the artificial calcium ionophore A23187. Anti-5b challenge of PMNs sequestered in the microvasculature of perfused rabbit lungs did, however, induce a markedly modified metabolite profile. Nonenzymatic hydrolysis products of leukotriene A4 were not detected, and 5-hydroxyeicosatetraenoic acid was markedly reduced. In contrast, cysteinyl leukotrienes were measured as predominant compounds, with rapid appearance of leukotriene C4 and more protracted generation of leukotriene E4. Leukotriene B4 and its omega-oxidation products were released with similar kinetics, but in lower amounts, as compared with the isolated PMN stimulation. Anti-5b challenge of PMNs coincubated with pulmonary artery endothelial cells in vitro, but not stimulation of either cell type alone, provoked marked generation of cysteinyl leukotrienes. These findings suggest modulation of PMN 5-lipoxygenase metabolism in favor of leukotriene A4 transfer to adjacent acceptor cells with subsequent enzymatic conversion to cysteinyl leukotrienes under conditions of lung vascular sequestration. Endothelial cells appear to serve as predominant cooperative cells under circumstances of blood-free lung perfusion. PMN-related transcellular eicosanoid synthesis may be involved in the pathogenesis of transfusion-evoked acute lung injury.

Acute Disease↗
PubMed1990

Reproduction of transfusion-related acute lung injury in an ex vivo lung model.

Leukoagglutinins are implicated in transfusion-related acute lung injury (TRALI). In the present study, severe lung vascular leakage was reproduced by application of a leukoagglutinating antibody of anti-5b specificity in an ex vivo lung model. The antibody originated from a multiparous donor-plasma, observed to cause noncardiogenic edema during transfusion therapy. Heated full plasma (anti-5b-titer 1/128) or purified immunoglobulin G fraction was used for the studies. Ex vivo isolated rabbit lungs were perfused with albumin buffer, and human granulocytes (PMN) were admixed to the recirculating perfusate. In presence of anti-5b antibody plus 5b-positive PMN plus rabbit plasma as complement-source, severe lung edema occurred after a latent period of 3 to 6 hours. Pulmonary artery pressure was only transiently and moderately increased, and the leakage reaction could be traced back to a several-fold increase in lung vascular permeability. In contrast, no vascular leakage was noted in lungs perfused in the absence of anti-5b antibody, PMN, or rabbit plasma. Moreover, no permeability increase occurred on use of 5b-negative PMN. This reproduction of TRALI in an ex vivo lung model corroborates the role of leukoagglutinating antibodies in initiating PMN-dependent respiratory distress and suggests a contribution of concomitant complement activation.

Agglutinins↗
PubMed1990

[10 years plasma exchange with the IBM (Cobe) 2997].

From 1979 to 1989 fifty patients, representing 18 different diagnoses/indications, were treated with 385 non-selective therapeutic plasma exchanges (TPE). In the first five years of the survey, the neurological diseases predominated; since 1984, these cases were treated by the Dept. of Neurology. Five % human albumin solution, fresh-frozen-plasma and saline solution were used as replacement fluids. In the beginning, the exchange volume was 1.5-2 times that of the patient's plasma volume, now it is less and varies with the disorder. ACD-A was used as anticoagulant. 11% of the TPE treatments side effects, and in another 3% technical or operator mistakes were noticed. As a supportive therapy, the plasma exchange was effective in the hyperviscosity syndrome, myasthenia gravis, thrombotic thrombocytopenic syndrome, myasthenia gravis, thrombotic thrombocytopenic purpura (TTP), hypercholesterolaemia, Guillain-Barré Syndrome, haemolytic crisis of a homozygous sickle-cell anaemia. There was, however, no definite convincing success in acute liver failure.

Anaphylaxis↗
PubMed1990

[Passive immunotherapy with polyvalent immunoglobulins in women with habitual abortions].

Intravenous immunoglobulins (IVIG) were used in an alternative approach to immunotherapy with allogeneic leukocytes to prevent recurrent spontaneous abortions (RSA). Twenty five women with a history of greater than or equal to 3 unexplained RSA were treated with IVIG during their next pregnancy. An initial dose of 30 g (0.5-0.6 g/kg body weight) was administered at gestational week 5-6. Treatment was continued every 3 weeks with 20 g (0.3-0.4 g/kg) and terminated by week 25. In primary RSA the success rate was 82-85%, which is in the same range as for leukocyte therapy. In contrast, IVIG was successful in only 40% of secondary aborters. We conclude that IVIG can be an effective treatment for prevention of primary RSA. Compared to leukocyte therapy the risks of transmission of infections and of HLA immunization can be avoided.

Abortion, Habitual↗
PubMed1990

[Serologic characterization of granulocyte-specific antibodies in neonatal alloimmune neutropenias].

Serological properties of nine granulocyte specific alloantibodies in maternal sera and sera of the newborns were investigated by granulocyte immunofluorescence, granulocyte agglutination and granulocyte cytotoxicity. In the immunofluorescence assay the reactions were more prominent than in the agglutination assay. Only one antibody yielded a positive reaction in the cytotoxicity assay. Four NA2-, two NA1- and one NB1-antibody could be identified. The immunofluorescence assay showed a mixed pattern with the NB1-antibody, indicating a heterogenous distribution of the NB1-antigen on granulocytes of some donors. In titration studies with heterozygous and homozygous donors a gene-doses-effect was demonstrable.

Agglutination Tests↗