Search PubMed⌕ Search

Biomedical subjects

P Y Le Pennec

Publications and source records attributed to P Y Le Pennec.

At least 19 recordsLinked to original sources
PubMed2005

[Quality control: sensitivity of the indirect antiglobulin test by filtration].

For ten years, the working party of immunohaematology of the French Society of Blood Transfusion organizes a quality control. After the modification of the law about the realization of erythrocyte typing and detection of unexpected red cell allo-antibodies, the quality control was performed in order to determine the sensitivity of the indirect antiglobulin test by filtration with a standard anti-RH1(D) produces by the National Reference Center of Blood Groups.

Blood Group Antigens↗
PubMed2005

[Annual Report 2004 - French National Reference Centre for Rare Blood Groups and Immunohaematology (CNRGS)].

In 2004, the French Reference Centre for Rare Blood Groups and Immunohaematology (CNRGS) developed 7 types of activities: 1) Studies of complex Immunohaematology issues (IH), 2) Studies of rare blood phenotypes, 3) the transfusion of patients showing complex issues, 4) IH reactive control in consistency with the 98/79/CE European Directive, 5) European studies and expertise on reactives and techniques, 6) Biotechnologies applied to blood groups, in particular RH, KEL, FY, JK, DO and CO, 7) Implementation of allo-immunization research programs (cellular immunology and grafting issues). The CNRGS efficiency is based on the 'reference-research' link thanks to the Inserm partnership and direct applications to patients allowing to a better risk management and control.

Academies and Institutes↗
PubMed2003

[The French reference laboratory for rare blood groups: activities in 2001].

The French reference laboratory for rare blood groups (CNRGS) is working for all participants of the transfusion chain: from the donors to the recipients; from the French Establishment for Blood to medical laboratories; from hospital to the haemovigilance network; from governmental agencies to European structures. This laboratory is in charge of: (1) studies of complex problems of immunohaematology; (2) studies of rare blood group phenotypes; (3) reagents quality controls; (4) production of biological standards; (5) specific specimen banks; (6) molecular studies of blood group antigens and antibodies involved; (8) panels of reference cells or DNA; (9) international exchanges.

Annual Reports as Topic↗
PubMed2003

Serological studies of monoclonal RH antibodies with RH1 (D), RH2 (C), RH3 (E) and RH5 (e) variant RBCs.

One hundred and forty five Mabs against RH antigens were tested. In this paper, we chose to detail reactivity of MoAbs directed against variant RBCs of the CNRGS collection for which we studied the molecular background. Because we developed procedures to identify variants of the RhD, RhC, RhE and Rhe antigens, we were especially interested in finding new monoclonal antibodies that could help us to characterize more accurately these variants. Therefore, we drew parallels between our procedures and results obtained with the 2001 workshop antibodies.

Antibodies, Monoclonal↗
PubMed2002

Section 1B: Rh flow cytometry. Coordinator's report. Rhesus index and antigen density: an analysis of the reproducibility of flow cytometric determination.

Fifty-seven IgG monoclonal anti-D antibodies were evaluated in the Rh flow cytometry section, in which 12 laboratories participated. Staining protocols and a fluorescein (FITC)-conjugated Fab fragment goat anti-human IgG (H + L) as a secondary antibody were recommended but not mandatory. A CcDEe red blood cell (RBC) sample that was shown to be homozygous for RHD by molecular methods was supplied and used as internal 'standard RBC' throughout all experiments. An RBC panel comprising two partial D and four weak D types was supplied as well. The use of standard RBC reduced the variability of the data among the laboratories and allowed the conversion of fluorescence data into epitope densities, which were compounded in an antigen density (antigen D per RBC). The highest antigen density was determined for DVI type III, followed by DVII and weak D type 3; the lowest antigen density were determined for weak D type 1 and type 2. Nine of the 12 participating laboratories discriminated three groups of aberrant RhD that had similar Rhesus indices (RI): D category VI with RI = 0; weak D type 2 and type 3 with an high RI; and D category VII and weak D type 1 with an intermediate RI. The antigen densities and the Rhesus indices obtained correlated well among the laboratories of this Workshop section despite different staining protocols, secondary antibodies and instrumentation.

Algorithms↗
PubMed2001

[Quantitative estimation by ELISA of IgG anti-D (RH1) antibodies in immunoglobulin preparations and in the sera of immunized donors].

Immunoglobulin preparations of anti-D (RH1) are injected to prevent haemolytic disease of the newborn. Such preparations are obtained by the fractionation of plasma from immunized donors. Measurement of the concentration of IgG anti-D is required to estimate the potency of anti-D preparations and sera from immunized donors. We have developed an ELISA method for the quantification of IgG anti-D. This method included the following steps, sensitization of red cells by anti-D, solubilization of red cell membranes by Triton, and eventually, measurement of IgG anti-D concentration by ELISA. The international reference preparation of anti-D (68/419) was used as a reference. With this method, we measured IgG anti-D concentrations in 5 immunoglobulin preparations of anti-D and in the sera of 10 donors immunized by D antigen. The ELISA results were compared with those obtained by automated hemagglutination. A mean anti-D concentration of 56.2 micrograms/mL was found by ELISA in immunoglobulin preparations. Similar results were obtained by automated hemagglutination (mean 52 micrograms/mL). In the sera of 10 D-immunized donors, anti-D IgG concentration varied from 2.2 to 59.8 micrograms/mL. A good correlation between ELISA and automated hemagglutination was observed in these sera (r = 0.98, p < 10(-7)). In conclusion, the ELISA technique offers an alternative to automated hemagglutination. It requires only the standard equipment necessary for immuno-enzymatic methods.

Blood Donors↗
PubMed2001

Two new alleles of the RHCE gene in Black individuals: the RHce allele ceMO and the RHcE allele cEMI.

Six unrelated individuals of Afro-Caribbean origin, whose red cells have a marked reduction of the Rhe antigen expression, have been identified. All exhibited the same serological profile with anti-e monoclonal antibodies and lacked expression of the high frequency e-related antigen hrS. Transcripts and genomic analysis showed that these phenotypes resulted from the presence of two new RHCE alleles, ceMO and cEMI. The ceMO allele corresponded to a RHce gene carrying a G667T mutation (exon 5) and was detected at the homozygous state in sample 1 and at the heterozygous state in samples 2-6. The G667T mutation resulted in a Val223Phe substitution on the Rhce polypeptide, in close proximity to Ala226 (e-antigen polymorphism), which might account for the altered expression of e. The ceMO allele is also associated with the lack of expression of the hrS antigen. The absence of the hrS antigen expression may have implications in transfusion as hrS-negative individuals may develop clinically significant antibodies. The cEMI allele corresponded to a silent RHE allele carrying a nine nucleotide deletion within exon 3 and was detected at the heterozygous state in sample 2. This deletion resulted in a shortened polypeptide of 414 residues (instead of 417) that was absent (or severely reduced) at the red cell surface, as the E antigen was undetectable using serology and Western blot analysis with anti-E reagents. In DNA-based polymerase chain reaction genotyping for RHE determination, the cEMI allele provided a false positive result as the cells carrying this allele are serologically phenotyped as E-negative. The incidence of this allele in the Black population is unknown but, as shown already for D genotyping, one must exercise caution when genotyping is performed to detect the e/E polymorphism.

Africa↗
PubMed2001

[External quality evaluation].

Since ten years, the immunohaematology working group of the French Society of Blood Transfusion has organized a quality control. Tests concern essentially the screening and identification of irregular antibodies, direct antiglobulin tests and elutions.

Autoantibodies↗
PubMed2000

[Trends in erythrocyte immunohematology reagents].

Until the 1980s blood group reagents had been produced from human or animal plasmas. Since then, the main change has been the increase of the use of monoclonal antibodies in laboratory reagents. Today, they are the basis of most reagents for blood group typing. They include murine (hybridomas) and human (Epstein-Barr virus immortalized lymphocytes and phage display) antibodies. The use of these antibodies leads to standardized methods of production and a better definition of the specificity through international works. The main drawback is the lack of antibodies for some blood group antigens. However, in the future these methods will be confronted with the development of DNA-based methods.

Animals↗
PubMed2000

[Immunologic risk analysis of blood transfusion: 1991-1998].

The immunologic risk associated to erythrocyte transfusions is bound to the polymorphism of blood group systems and to the respect of blood transfusion regulations. The results of three studies are presented, which were carried out respectively by the French Society of Blood Transfusion, the National Institute of Blood Transfusion and the National Haemovigilance Network. Two hundred and twenty-seven cases of immunologic accidents are analysed using the Kaplan's interpretation model and the traditional method of process analysis. The results show three critical factors in the occurrence of this type of incident: the relevance of the clinical examinations prescribed, the way in which the biological results are taken into account, and the relationship/exchange of information between private and public hospitals, and blood transfusion centers.

ABO Blood-Group System↗
PubMed2000

Haemovigilance and transfusion safety in France.

The risks associated to red cell and platelet transfusions are essentially bound to the polymorphism of blood group antigens and to transfusion transmitted agents including virus, bacterias.... In France, the haemovigilance system and several investigations allowed to measure these different kinds of risks. We also developed analysis of failures in order to prevent errors and accidents to increase blood safety.

Blood Transfusion↗
PubMed1999

[Quality control of reactant lots at the Nation Blood Group Reference Center (CNRGS). Data for the year 1998].

The reagents used for blood group analyses are subject in France to the same regulations as other reagents. A file must be submitted for each reagent to the Agence française de sécurité sanitaire des produits de santé. Furthermore, each production lot must be checked by the Centre national de référence pour les groupes sanguins (CNRGS) for control before marketing. These controls allow a comparative quality assessment of the reagents. The investigation by the CNRGS of the problems encountered in the every day use of these products makes this quality control even more accurate.

Blood Banks↗
PubMed1999

Evaluation by enzyme-linked immunosorbent assay of IgG anti-D and IgG subclass concentrations in immunoglobulin preparations.

BACKGROUND: Anti-D immunoglobulin preparations are injected to prevent hemolytic disease of the newborn. The concentration of IgG anti-D in these preparations is usually determined by an automated hemagglutination technique using as a reference a calibrated preparation of anti-D, but the method requires special equipment and cannot be routinely applied to measure the IgG subclasses of anti-D in these preparations. STUDY DESIGN AND METHODS: Taking advantage of a recently described enzyme-linked immunosorbent assay (ELISA) for the determination of the anti-D concentration in sera of alloimmunized pregnant women, IgG anti-D and IgG subclass concentrations were measured in the international reference preparation (IRP) coded 68/419, 10 anti-D immunoglobulin preparations, and sera of 15 D-immunized volunteers. RESULTS: An IgG anti-D concentration of 61.5 +/- 4.8 microg per ampoule (mean +/- SD) was found by ELISA in IRP 68/419. This result was in agreement with previous determinations obtained by radioimmunoassay (60 microg/ampoule). The IgG subclass concentration of anti-D in this preparation was 48.4 microg of IgG1 (78.6%), 3.0 microg of IgG2 (4.8%), 9.7 microg of IgG3 (15.8%), and 0.4 microg of IgG4 (0.7%). The mean proportion of IgG subclasses of anti-D in 10 immunoglobulin preparations was similar (81.7% for IgG1, 5.0% for IgG2, 12.7% for IgG3, and 0.6% for IgG4). In the sera of 15 immunized volunteers, the IgG anti-D concentration varied from 3.1 to 68.4 microg per mL. The mean IgG subclass composition of anti-D was 79.3 percent for IgG1, 2.2 percent for IgG2, 18.1 percent for IgG3, and 0.4 percent for IgG4. The proportions of IgG3 anti-D in these sera were found to range between 1 percent and 87 percent, as in the sera of D-alloimmunized pregnant women. CONCLUSION: ELISA provides an alternative to the radioimmunoassay and the automated hemagglutination technique. In addition, it allows the evaluation of the absolute concentration of each IgG subclass of anti-D in immunoglobulin preparations and necessitates only the conventional equipment required for an immunoenzymatic assay.

Enzyme-Linked Immunosorbent Assay↗
PubMed1998

Arg89Cys substitution results in very low membrane expression of the Duffy antigen/receptor for chemokines in Fy(x) individuals.

The Duffy (FY) blood group antigens are carried by the DARC glycoprotein, a widely expressed chemokine receptor. The molecular basis of the Fya/Fyb and Fy(a-b-) polymorphisms has been clarified, but little is known about the Fyx antigen and the FY*X allele associated with weak expression of Fyb, Fy3, Fy5, and Fy6 antigens. We analyzed here the structure and expression of the FY gene in 4 Fy(a-bweak) individuals. As compared with Fy(a-b+) controls, the Fy(a-bweak) red blood cell membranes contained residual amount of DARC polypeptide and these cells were poorly bound by anti-Fy antibodies and chemokines. The FY gene from Fy(a-b+) and Fy(a-bweak) individuals differed by one substitution, C286T. The resulting Arg89Cys amino acid change reduced the binding of anti-Fy antibodies and chemokines to DARC transfectants. We concluded that the Fybweak donors carried the FY*X allele at the FY locus and that the Fyx antigen corresponds to highly reduced expression of a grossly normal Fyb polypeptide caused by the Arg89Cys substitution. Because FY is a single copy gene, this defect should also affect DARC expression in nonerythroid cells. Because the Fyx phenotype is not associated with apparent clinical consequences, we discussed these findings in the light of the putative roles of DARC in various tissues. Finally, we developed a Fyx DNA typing assay that should be useful for genetic studies and clinical transfusion medicine.

Alleles↗
PubMed1998

Characterization of the gene encoding the human Kidd blood group/urea transporter protein. Evidence for splice site mutations in Jknull individuals.

The Kidd (JK) blood group is carried by an integral membrane glycoprotein which transports urea through the red cell membrane and is also present on endothelial cells of the vasa recta in the kidney. The exon-intron structure of the human blood group Kidd/urea transporter gene has been determined. It is organized into 11 exons distributed over 30 kilobase pairs. The mature protein is encoded by exons 4-11. The transcription initiation site was identified by 5'-rapid amplification of cDNA ends-polymerase chain reaction at 335 base pairs upstream of the translation start point located in exon 4. The 5'-flanking region, from nucleotide -837 to -336, contains TATA and inverted CAAT boxes as well as GATA-1/SP1 erythroid-specific cis-acting regulatory elements. Analysis of the 3'-untranslated region reveals that the two equally abundant erythroid transcripts of 4.4 and 2.0 kilobase pairs arise from usage of different alternative polyadenylation signals. No obvious abnormality of the Kidd/urea transporter gene, including the 5'- and 3'-untranslated regions, has been detected by Southern blot analysis of the blood of two unrelated Jknull individuals (B.S. and L.P.), which lacks all Jk antigens and Jk proteins on red cells, but was genotyped as homozygous for a "silent" Jkb allele. Further analysis indicated that different splice site mutations occurred in each variant. The first mutation affected the invariant G residue of the 3'-acceptor splice site of intron 5 (variant B.S.), while the second mutation affected the invariant G residue of the 5'-donor splice site of intron 7 (variant L.P.). These mutations caused the skipping of exon 6 and 7, respectively, as seen by sequence analysis of the Jk transcripts present in reticulocytes. Expression studies in Xenopus oocytes demonstrated that the truncated proteins encoded by the spliced transcripts did not mediate a facilitated urea transport compared with the wild type Kidd/urea transporter protein and were not expressed on the oocyte's plasma membrane. These findings provide a rational explanation for the lack of Kidd/urea transporter protein and defect in urea transport of Jknull cells.

Base Sequence↗
PubMed1998

[Final bedside verification: results of a national survey of reagents and devices used in France].

The national reference Center for blood groups checked samples of reagents and devices used in France for a definitive verification of pretransfusion ABO tests performed at the patient's bedside, as defined by French health authority regulations. The results of an initial inquiry was published in 1991. The new study shows no significant improvement of the quality of reagents and devices. This is a major concern considering the importance of ABO incompatibility in severe hemolytic transfusion reactions.

ABO Blood-Group System↗
PubMed1998

Heterogeneity of blood group RhE variants revealed by serological analysis and molecular alteration of the RHCE gene and transcript.

After testing red cells from 12 RhE variants with a panel of anti-E monoclonal antibodies (MoAbs), four patterns of reactivity were detected indicating that the MoAbs may recognize four distinct E epitopes designated epE1, epE2, epE3 and epE4. The variants were classified into four categories (cat EI to EIV) which carried epE1 and epE2, epE1 and epE4, epE1, epE3 and epE4, and all four epitopes, respectively. Molecular analysis of the transcripts and genomic DNA of the variants from cat EI, EII and EIII displayed three distinct genetic alterations. Cat EI variants exhibited a point mutation (T500A) in exon 4 of the RHCE gene that resulted in a Met167Lys substitution in the third extracellular loop of the RhcE protein. Cat EII variant carried a hybrid gene structure characterized by replacement of exons 1-3 (or 2-3) of the RHCE gene by their specific counterparts in the RHD gene. This latter variant was also associated with a weak expression of the RhC antigen. In cat EIII variants there was a partial DNA exchange of exon 5 sequences (nt 697 and 712) between the RHCE and the RHD genes, generating a hybrid Rh cE-D-cE protein carrying the Glu233 and Val238 substitutions. The serological and molecular studies of the RhE variants indicated that: (i) the RhE antigen is a mosaic composed of at least four epitopes and proline at position 226 is necessary but not sufficient for the full expression of the E antigen, (ii) the lack of RhE epitope(s) is associated with heterogenous molecular alterations of the RHCE gene, and (iii) amino-acids located on the third and fourth extracellular loops of the RhCE polypeptide are critical for some RhE epitopes expression.

Antibodies, Monoclonal↗