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M Jeannet

Publications and source records attributed to M Jeannet.

At least 19 recordsLinked to original sources
PubMed1992

[Swiss Register for unrelated bone marrow donors: preliminary results].

Bone marrow transplantation from the unrelated volunteer donor is today a realistic possibility for patients lacking an HLA-identical family donor. In 1988, the Swiss Unrelated Bone Marrow Donor Registry was founded to coordinate such bone marrow transplants and create the Swiss volunteer donor registry. Thus for a search has been initiated for 71 patients and 16 transplants have been performed. Donor and recipient were HLA-A-, -B- identical by serology and HLA-Dr-identical by DNA-oligotyping. 10 of the 16 patients are alive without signs of basic disease 2 weeks to 2 years and 4 months after the transplant. These results illustrate that unrelated donor transplantation, using careful selection criteria, is a realistic new therapeutic modality.

Adolescent↗
PubMed1992

Evolution of mixed chimerism after allogeneic bone marrow transplantation as determined on granulocytes and mononuclear cells by the polymerase chain reaction.

To evaluate the clinical relevance of mixed chimerism (MC) after allogeneic bone marrow transplantation (BMT), we developed a method based on amplification of DNA minisatellites by the polymerase chain reaction (PCR). This sensitive method by which MC lower than 1% can be detected is applicable to any patient-donor pair. Furthermore, because the analysis requires only small amounts of DNA, it allowed us to analyze samples early after BMT and during graft rejection. Results were obtained within 48 hours after blood sampling. Determination of MC in granulocytes (GR) and in mononuclear cells (Mnc) was performed in 20 patients treated for various hematologic malignancies. In patients who received untreated BM, recipient cells disappeared rapidly after BMT. In patients transplanted with T-cell-depleted BM, MC occurred in 15 of 16 cases. The percentage of host Mnc was always significantly higher than the percentage of host GR. The evolution of MC in patients who received T-cell-depleted marrow showed distinct patterns depending on whether patients remained in continuous complete remission, relapsed, or rejected their grafts. During complete remission, a relatively stable and significant number of host cells could be detected during the first 2 years after transplantation. Thereafter, their number decreased, but even after 4 years, low numbers of host cells could persist. When the patients relapsed, an increase in host Mnc was monitored without significant changes in the number of donor Mnc. In contrast, after the relapse, donor GR were no longer detected. Two cases of graft rejection were studied. Directly after the onset of the rejection, donor GR and Mnc disappeared rapidly. During that period, no significant changes in the number of host Mnc were detected.

Adult↗
PubMed1992

Apparent HLA DR triplet due to the coexpression of a DRB5-encoded molecule on a DR1 haplotype.

HLA DR1 molecules are coded by a single polymorphic DRB1 gene. We have observed rare DR1 cells in one Caucasoid family and three unrelated individuals that also reacted with some anti-DR2 sera. Since the second DR antigen was normally expressed, these cells appeared as triplets. Contrary to serology, the cells were not typed by HTCs defining Dw2, Dw12, and Dw21. Further investigations on these unusual DR1+2* haplotypes were conducted by DNA oligotyping and by sequencing of the DRB first-domain exon. The results showed that these DR1 haplotypes, besides their DRB1*0101 allele, carried also a DRB5*0101 allele.

Adult↗
PubMed1992

The decrease in organ donations from 1985 to 1990 caused by increasing medical contraindications and refusals by relatives.

After the progressive improvement in the results of organ transplantation we now face the challenge of shortage in organ supply. The decreasing number of organ retrievals performed in 1990 at our hospital has raised questions concerning loss of potential organ donors and opposition to donation by the next of kin. We investigated these questions and the number of organs available per million inhabitants in the area covered by our university hospital. Our surgical intensive care unit provides about 85% of all organ donations for this area. To this end, all 375 deaths occurring in the surgical ICU during the period between January 1, 1985 and December 31, 1990 were analyzed. Of 138 brain-stem deaths, 43 presented medical contraindications preventing organ harvesting for transplantation. Consent for donation was sought from the families of the 95 remaining potential donors and was refused for 17 patients. Organ retrieval followed all of the 78 agreements to donate, so that no suitable donor was lost. Over the 6 years surveyed, a progressive decrease in organs procured was observed, due to an increase of medical contraindications to organ harvesting for transplantation (P less than 0.001) and a higher rate of refusals to donate organs (P less than 0.002). The rate of kidney retrieval was thereby reduced from 45 to less than 25 per million population per year between 1985 and 1990 for our hospital's catchment area. The reasons cited by the families for denying organ donation suggest that the publicity campaigns aimed at the medical community and the public concerning organ transplant programs should be modified, and that a careful selection of indications for transplantation seems mandatory.

Attitude↗
PubMed1992

[Polymorphism of HLA class I loci HLA-A, -B, -C, in the Mandenka population from eastern Senegal].

A sample of 162 Mandenkalu from Eastern Senegal has been typed for three HLA class I loci: HLA-A, -B and -C. The Mandenka population presents a very high genetic variability with 15 alleles for locus A, 24 alleles for locus B, and at least 8 alleles for locus C. The calculated heterozygosities for the three loci A, B, and C are respectively 0.884, 0.944 and 0.829. The Mandenkalu allelic frequencies are close to that found in other sub-Saharan populations. They show, however, some peculiarities like the occurrence of the Bw 56 allele and the high frequencies of both B5 and B35.

Alleles↗
PubMed1992

Clonal imbalances of serum immunoglobulins after allogeneic bone marrow transplantation: an analysis by high-resolution two-dimensional gel electrophoresis.

The clonality pattern of immunoglobulins (Igs) produced after allogeneic bone marrow transplantation (BMT) was studied by high-resolution two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) of serum samples and purified Igs. With this technique, the light (L) chain of a monoclonal Ig usually appears as a single spot. Thus, the degree of clonal diversity of the functional B cells can be appreciated by the electrophoretic pattern of the serum L chains. Furthermore, 2D-PAGE allows a semi-quantitative determination of prominent Ig clones according to the size of L chain spots. We found that serum electrophoretograms of 8/19 patients after BMT (5-9 months) revealed L chain patterns which were similar to those of normal polyclonal Igs, that is, less than five distinguishable small spots among a cloud-like indiscrete L chain spots region ('polyclonal' pattern). A spectrum of clonal abnormalities was observed on the electrophoretograms of 11/19 patients: in five patients, multiple small L chain spots (corresponding to Ig concentrations between 0.2 and 2 g/l) were detected ('oligoclonal' pattern), whereas in six others, 'typical' monoclonal Igs (Ig concentrations > 2 g/l) were observed with (3/19 patients) or without (3/19 patients) multiple small clonal components. Sequential analysis of serum obtained from patients at different times after BMT revealed that imbalanced clonal reconstitution was transient and evolved towards apparently normal polyclonal Ig production. Our observations show that the development of clonal 'gammopathies' after BMT is a frequent, but not obligatory phenomenon. It may reflect a transient restriction of the B cell repertoire either through a limited outgrowth of precursor cells or through selective antigenic pressures.

Antibody Diversity↗
PubMed1992

HLA-DR polymorphism in a Senegalese Mandenka population: DNA oligotyping and population genetics of DRB1 specificities.

HLA class II loci are useful markers in human population genetics, because they are extremely variable and because new molecular techniques allow large-scale analysis of DNA allele frequencies. Direct DNA typing by hybridization with sequence-specific oligonucleotide probes (HLA oligotyping) after enzymatic in vitro PCR amplification detects HLA allelic polymorphisms for all class II loci. A detailed HLA-DR oligotyping analysis of 191 individuals from a geographically, culturally, and genetically well-defined western African population, the Mandenkalu, reveals a high degree of polymorphism, with at least 24 alleles and a heterozygosity level of .884 for the DRB1 locus. The allele DRB1*1304, defined by DNA sequencing of the DRB1 first-domain exon, is the most frequent allele (27.1%). It accounts for an unusually high DR13 frequency, which is nevertheless within the neutral frequency range. The next most frequent specificities are DR11, DR3, and DR8. Among DRB3-encoded alleles, DR52b (DRB3*02) represents as much as 80.7% of all DR52 haplotypes. A survey of HLA-DR specificities in populations from different continents shows a significant positive correlation between genetic and geographic differentiation patterns. A homozygosity test for selective neutrality of DR specificities is not significant for the Mandenka population but is rejected for 20 of 24 populations. Observed high heterozygosity levels in tested populations are compatible with an overdominant model with a small selective advantage for heterozygotes.

Base Sequence↗
PubMed1991

Selection of unrelated donors for bone marrow transplantation is improved by HLA class II genotyping with oligonucleotide hybridization.

As the demand for donors for bone marrow transplantation increases, the use of HLA-matched, genetically unrelated donors represents a promising strategy. It is well documented that the clinical outcome of bone marrow transplantation is directly dependent on optimal matching for HLA class I and class II specificities. Molecular studies have revealed the existence of a much larger number of HLA class II alleles than was anticipated, many of which cannot be recognized by routine serological typing. Currently this "hidden" polymorphism represents a major limitation to the generalized use of unrelated donors for bone marrow transplantation. It has recently become possible, however, to identify HLA allelic polymorphism directly at the DNA level by hybridization with sequence-specific oligonucleotide probes ("HLA oligotyping") after amplification of DNA by polymerase chain reaction. In this study, we have investigated whether donor-recipient pairs that are fully matched for HLA by serology are truly HLA-DR, -DQ, and -DP identical and to what extent class II differences influence the primary mixed lymphocyte culture. We show that HLA oligotyping, performed on 50 pairs of HLA class I and II serologically matched individuals, can indeed reveal phenotypically relevant allelic differences at either DRB or DQB loci in 56% of these pairs and can therefore improve HLA class II typing and the choice of bone marrow donors quite significantly. Oligotyping for DRB/DQB/DPB polymorphism also allows prediction of a positive mixed lymphocyte culture, as established in 31 donor/recipient combinations, and even detection of polymorphic differences that were not revealed by this test. This approach is well suited for accurate HLA typing of large pools of bone marrow donors and was successfully applied to select fully matched donors for bone marrow transplantation.

Bone Marrow Transplantation↗
PubMed1991

Additional complexity within the HLA-D region: sequence analysis of two new DRw13-DQw7 haplotypes.

HLA-DRB1 is by far the most polymorphic locus within the HLA-D region with now well over 40 alleles. Nearly one fourth of these alleles are subtypes of DRw6, and these are in most cases undetectable by routine typing procedures. In this paper we present the molecular characterization of two new Caucasian DRw13-DQw7 haplotypes by DNA sequencing of the polymorphic first domain exons of DRB1 and DRB3 loci. The first haplotype, DRB1*1301-DRB3*0101-DQB1*0301, has arisen by a recombination between locus DRB1 from a DRw13-DQw6 haplotype and DQA1 from a DR4-DQw7 haplotype, as determined by DNA sequencing, DQ oligotyping, and restriction fragment length polymorphism typing. The second haplotype, DRB1*1305-DQB1*0301, is characterized by the novel DRB1*1305 allele differing from DRB1*1301 by three amino acids. It probably arose by a gene conversion event between a DRw13-DQw6 allele and DRB1*1101. This allele represents a DRw11/DRw13 hybrid DR molecule with a DRw13 serological epitope in the second hypervariable region and a Dw5 cellular epitope in the third hypervariable region. As determined by sequencing of locus DRB3, this allele is associated with DRw52b. Our molecular analysis of the complex HLA-DRw13 group now allows unambiguous DNA typing of all five DRw13 alleles with seven oligonucleotides, a significant improvement in the context of organ transplantation.

Amino Acid Sequence↗
PubMed1991

Safety and immunogenicity of a genetically engineered human immunodeficiency virus vaccine.

A phase 1 trial of a candidate human immunodeficiency virus type 1 (HIV-1) vaccine was done in 25 healthy seronegative subjects. The antigen, env2-3 (SF2), was a nonglycosylated polypeptide representing the gp120 region of the env gene of the HIV-1(SF2) isolate. It was produced in genetically engineered yeast as a denatured molecule incapable of binding CD4. A synthetic lipophilic muramyl tripeptide (MTP-PE) was used as an adjuvant. Ten subjects received adjuvant alone and 15 received 50- or 250-micrograms doses of env2-3 (SF2) administered intramuscularly in two immunization regimens. In general, adjuvant and vaccine were well tolerated. Antibody responses to both the homologous antigen, env2-3 (SF2), and antigens from other highly divergent HIV isolates were elicited in the majority of vaccine recipients. However, antibody titers were low, without neutralizing activity. In 9 of 11 subjects who received the complete vaccine immunization series, a significant specific T lymphocyte response was observed.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1991

Application of HLA-DR oligotyping to 110 kidney transplant patients with doubtful serological typing.

In renal transplantation a good HLA-DR match is associated with a higher success rate of graft outcome. However, due to a number of technical problems, reliable serological DR typing cannot always be obtained, and the very large number of HLA-DR alleles now discovered renders such DR matching more difficult. In view of the medical importance of HLA class II polymorphism in transplantation immunology, we have developed a simple HLA-DR oligotyping procedure on PCR-amplified DNA, by hybridization with 14 synthetic oligonucleotide probes able to recognize all major HLA-DR specificities. In particular, the probes used in this study allow the unambiguous discrimination of the DRw11, w12, w13, w14-Dw9 specificities or of rare alleles such as DR-Br or DRw13-DwHAG, which are very often difficult or impossible to identify by serology. In order to explore the potential of this methodology, we have analyzed by oligotyping 110 kidney transplant patients with doubtful or unreliable serological assignment, or with DR blank alleles. Comparison between serology and oligotyping shows that in 66.3% of the patients we observed an excellent correlation. About half these patients are homozygotes, as ultimately verified by RFLP typing. In 26.4% of the patients however, at least one HLA-DR antigen was discrepant, and in 7.3% of the cases oligotyping resolved uninterpretable serology. Almost all of the discrepancies were due to errors in allele assignment within the DRw52 group, mostly in the case of DRw13 alleles. This study confirms the expected qualitative advantage of the oligotyping technique and its simplicity as compared with the RFLP DNA typing procedure. Large scale application of the oligotyping methodology will therefore be beneficial to optimize HLA-DR matching in organ transplantation, particularly in high responders with first kidney graft rejection.

Base Sequence↗
PubMed1991

Absence of DRw15/3 and of DRw15/7 heterozygotes in Caucasian patients with systemic lupus erythematosus.

Polymorphic MHC class II molecules determine immune responsiveness towards pathogens and also contribute to susceptibility or resistance to a number of different autoimmune diseases, including systemic lupus erythematosus (SLE). The HLA-DR and -DQ alleles of 52 patients with SLE were analyzed by serology and, for 42 patients, HLA-DRB1, -B3 and DQB1 allelic polymorphism was determined by oligotyping on PCR-amplified DNA. While we confirm the increase of DR3 (44.2% versus 16% in controls; p less than 0.001) reported by others, we observed a complete absence of DRw15(2)/DR3 and DRw15(2)/DR7 heterozygotes among Caucasian patients. Moreover HLA-DQB1 oligotyping revealed the absence of DQB1*0602/0201 heterozygotes in our panel of Caucasoid SLE patients. Since both DR3 and DR7 haplotypes share the same DQB1*0201-encoded DQ beta chain, and since DRw15 is known to be in linkage disequilibrium with DQA1*0102, it can be predicted that DQA1*0102/DQB1*0201 combinations are absent in Caucasian patients. We therefore propose that a DQA1*0201/DQB1*0201-encoded HLA-DQ trans-dimer formed in these heterozygotes might function as a suppressor-inducer molecule that confers resistance against SLE.

Blotting, Southern↗
PubMed1990

[Analysis of the frequency of anti-HLA hyperimmunization in patients with kidney transplantation].

Highly sensitized patients tend to accumulate on renal transplant waiting lists. A long period of time is often needed for the identification of a compatible graft possessing the rare HLA antigens against which these patients are not immunized. The aim of this study was to identify factors which could explain the fact that the percentage of highly sensitized patients on the Swiss waiting list is one of the highest in Europe. Although no definite conclusion is possible, it seems that this phenomenon is not related to the fact that many of these patients have received mismatched grafts. It seems rather to result from the relatively high rate of transplantations for non-sensitized versus highly sensitized patients in comparison to what is encountered in other countries. The fact that this probably represents only a relative increase in hypersensitized patients is confirmed by the stability of the absolute number of these patients on the waiting list during recent years.

Europe↗
PubMed1990

A new HLA-DRB1 allele within the DRw52 supertypic specificity (DRw13-DwHAG): sequencing and direct identification by oligonucleotide typing.

Molecular analysis of HLA class II polymorphism represents a crucial parameter for HLA matching in transplantation immunology, for the study of HLA-disease association and for the understanding of major histocompatibility complex (MHC)-restricted antigen presentation. We report here the DNA sequence and the deduced amino acid sequence of the polymorphic first domain exon of the DRB1 and DRB3 alleles of the homozygous cell line HAG (DRw13-DwHAG-DQw7). The DRB1 sequence represents a new DRB allele, which clearly shows a close relationship to other DRB1 genes from the DRw52 group and is now officially named DRB1* 1303. The DRB1* 1303 allele is very similar to the two DRw13 alleles we have described earlier, with only five amino acid differences at positions 32, 37, 47, 57 and 71. Furthermore, its sequence in the third hypervariable region is unique among all known DRB1 and DRB3 alleles. The sequence of the DRB3 gene of HAG shows that it corresponds to the previously described DRB3* 0101 (DRw52a) allele. In addition we present analyses of a panel of healthy blood donors and leukemic patients by oligonucleotide typing showing that this new HLA-DR specificity can now be unequivocally identified in routine oligotyping with an allele-specific oligonucleotide probe.

Alleles↗