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M Jeannet

Publications and source records attributed to M Jeannet.

At least 73 records · Page 4Linked to original sources
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↗
PubMed1990

Immunological heterogeneity of autoreactive T lymphocytes against the nicotinic acetylcholine receptor in myasthenic patients.

The response of human T lymphocytes against the nicotinic acetylcholine receptor (AChR) was studied in five patients with myasthenia gravis (MG) and in six healthy donors using either native Torpedo AChR or recombinant protein derived from the mammalian AChR alpha subunit (X4, residues 6-216 of mouse AChR alpha subunit). The present study demonstrates that (a) AChR-specific T helper cell lines can be generated from MG patients [either from peripheral blood lymphocytes (PBL) or from thymocytes] as well as from PBL of normal controls, (b) lymphocytes from MG patients, but not from controls, recognize the mammalian AChR but not the Torpedo receptor, (c) in humans, the HLA-DR2-associated T cell epitope is probably located in the region of residues 162-216 of the AChR alpha subunit and (d) there is a considerable heterogeneity of autoreactive T cell responses: (i) T cell lines from different HLA-type donors have distinct epitope profiles; (ii) the epitope specificity of the PBL-derived T cell line is different from that of the thymocyte-derived line; (iii) the epitope specificities of patient-derived T cell lines are different from those generated from normal controls who share the same HLA phenotype.

Animals↗
PubMed1990

Complete analysis of HLA-DQB1 polymorphism and DR-DQ linkage disequilibrium by oligonucleotide typing.

HLA class II polymorphism is functionally important in the control of immune responses, in transplantation immunology, and in the suceptibility to autoimmune diseases. HLA-DQA1 and -DQB1 genes exhibit a larger degree of allelic polymorphism than usually recognized by routine serology. We have therefore performed an extensive analysis of DQB1 polymorphism by oligotyping. A set of 12 oligo probes was hybridized on polymerase chain reaction-amplified DNA, thus allowing the detection of 12 DQB1 alleles, as demonstrated in homozygous as well as in heterozygous individuals. This highly sensitive detection system is particularly relevant within the DQw1 specificity where the 7 allelic sequences can easily be identified. The DQ-DR linkage disequilibrium was analyzed by oligotyping of 80 Caucasoid heterozygous individuals (160 haplotypes), and very tight associations were observed between DRB1 and DQB1 alleles. Five DRB1 alleles, DR-BON, DR4/Dw4 or Dw14, DR7, DRw8.3, and DRw11, however, can be associated with different DQB1 alleles. Moreover the DRB1 and DQB1 oligotyping analysis performed on 20 randomly chosen DRw8 Caucasoid individuals showed a high prevalence of the DRB1*0801-DQB1*0402 haplotype. By combining the analysis of allelic variations at DRB1, DRB3, and DQB1 loci, we can detect 33 different DR-DQ combinations in our panel of Caucasoid individuals. We now apply DQB1 oligotyping on a routine basis for optimal matching of unrelated donors for bone marrow transplantation.

Alleles↗
PubMed1990

A new approach for the analysis of HLA class II polymorphism: 'HLA oligotyping'.

Histocompatibility typing allows the matching of patients and donors in organ transplantation, and the accuracy of HLA matching influences to a great extent the clinical outcome. Recent breakthroughs in the molecular biology of HLA class II genes have revealed that the degree of HLA diversity and polymorphism is in fact much greater than was expected on the basis of the traditional serological HLA typing assays. In parallel, it has become possible to analyse this extensive polymorphism directly at the level of the HLA class II genes and of their DNA sequences. We have described a DNA typing procedure referred to as 'HLA oligotyping' which is based on the hybridisation of allele and loci specific oligonucleotide probes. This procedure has now become operational on a large scale and this review describes the principles and major applications of the technique. It consists in the hybridisation of DNA with informative sequence-specific oligonucleotide probes, following an amplification of DNA in vitro by the polymerase chain reaction (PCR). The use of this highly sensitive technique for HLA-DR, -DQ and -DP typing is discussed, focusing on the clinical applications in the field of organ transplantation, particularly for bone marrow transplantation with unrelated donors. It now allows the unambiguous identification of all HLA subtypes, including those that cannot be recognised otherwise, and it represents powerful complement to current methods of HLA typing. Finally this methodology is widely used in HLA-disease association studies, aiming at the characterisation of HLA class II epitopes involved in the susceptibility or resistance to autoimmune diseases.

Antigen-Presenting Cells↗
PubMed1990

Priming of CD4+ T cells specific for conserved regions of human immunodeficiency virus glycoprotein gp120 in humans immunized with a recombinant envelope protein.

A nonglycosylated denatured form of human immunodeficiency virus (HIV) 1 glycoprotein gp120 (Env 2-3), which does not bind to CD4, was used with muramyl tripeptide as adjuvant to immunize HIV-seronegative healthy volunteers. In all the volunteers, three 50-micrograms injections of Env 2-3 induced priming of CD4+ T cells specific for conserved regions of the native glycosylated gp120. Moreover, we found that several major histocompatibility complex class II (DR) alleles can function as restriction molecules for presentation of conserved epitopes of gp120 to T cells, implying that a T-cell response to these epitopes can be obtained in a large fraction of the population. The possibility to prime CD4+ T cells specific for conserved epitopes of a HIV protein is particularly important in view of the lack of such cells in HIV-infected individuals and of a possible role that CD4+ T cells may play in the development of protective immunity against AIDS.

Alleles↗
PubMed1990

Susceptibility or resistance to lysis by alloreactive natural killer cells is governed by a gene in the human major histocompatibility complex between BF and HLA-B.

The specificity recognized on normal allogeneic cells by a given alloreactive (1-anti-A) natural killer clone is controlled by a gene locus termed EC1. Because the EC1 locus was previously shown to be located on chromosome 6, families characterized by a recombinant major histocompatibility complex haplotype were analyzed to map this locus more precisely. The breakpoint of recombination was studied by standard HLA typing, complement typing, and restriction fragment length polymorphism analysis of a series of genes located between the complement cluster genes and HLA-B within the major histocompatibility complex region. Three of 10 families analyzed were informative. From the data obtained, the EC1 locus maps between BF and HLA-B and presumably is one of the normal genes recently described in this region.

Antigens, Differentiation↗
PubMed1989

[Immunization with partner's lymphocytes of women subject to recurrent early spontaneous abortions].

In the early 1980s a new, although still empirical therapy was proposed for women undergoing recurrent spontaneous abortions of unknown origin, where an immunologic cause is suspected. The treatment consists in immunization of the women with human lymphocytes. We report here on our own first experience with this modality and discuss the results in light of the different immunologic tests which were performed before and after immunization with paternal lymphocytes. 11/13 treated women belong to the group with abortions of alloimmune origin, 6/11 patients were delivered of a normal baby in the 40th week of gestation (median), one patient is pregnant in the 36th week of gestation, 2 had abortions again and two women are not yet pregnant. Further investigations suggest that 2/13 women had abortions of autoimmune origin; one of these women had a normal baby in the 33rd week of gestation and the other is pregnant in the 18th week.

Abortion, Habitual↗