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Biomedical subjects

H Bétuel

Publications and source records attributed to H Bétuel.

At least 19 recordsLinked to original sources
PubMed1998

Generation of stable monocyte-derived dendritic cells in the presence of high concentrations of homologous or autologous serum: influence of extra-cellular pH.

Recent studies have highlighted the high degree of differentiation of monocytes. Indeed, dendritic cells (DC) can be generated from monocytes, in the presence of appropriate cytokines. However, human serum is usually avoid in such cultures. Here, we report that human serum does not inhibit generation of mature DC from blood monocytes, but rather that extra-cellular pH may play an important role in the regulation of monocyte differentiation. Indeed, monocytes cultured at pH 7.4 in the presence of high concentrations of human serum developed efficiently into mature DC, as opposed with monocytes cultured at pH 7. These pH 7.4 cultured DC presented features characteristic of mature DC, at the phenotypical, functional and morphological levels. In addition, these DC were stable, with respect to their sustained expression of CD83 and CD86, upon withdrawal of cytokines. Finally, when autologous plasma was used instead of homologous serum, differentiation of monocytes into mature DC was efficient, as well. Thus, altogether, our data show the importance of extra-cellular pH on differentiation of monocyte-derived DC in the presence of human serum, which should be maintained at plasma levels.

Antigens, CD↗
PubMed1993

Functional dissection of the serological DR LYGUE and genotypic DRB1*1303 specificities using a tetanus toxin-specific T-cell clone.

The DRB1 sequence of the homozygous cell line HAG (DR13-DwHAG-DQ7) represents a new DRB allele assigned DRB1*1103, whereas its DRB3 sequence corresponds to the previously described DRB3*0101 (DR52a) allele. The DRB1*1303 gene product is undetectable by current sera used in routine serology typing. We report here direct evidence that the MHC molecule encoded by the DRB1*1303 gene is functional in antigen presentation and in T-cell restriction. We describe a T-cell clone specific for tetanus toxin whose restriction pattern strictly follows the DRB1*1303 allele, as defined by oligonucleotide typing. It also follows the serologic reactivity with the serum LYGUE and also the DwHAG MLC-defined specificity pattern, with one exception. The potential functional sites for the DRB1*1303 gene product involved in T-cell restriction were deduced from sequence comparisons between DRB1*1303 and closely related DRB1 alleles. The relevant as substitutions were located within close proximity to each other on the HLA class II structural model. Our results demonstrate that 1) DRB1*1303 is functional in antigen presentation and T-cell restriction 2) the functional region involved in antigen presentation and T-cell restriction by DRB1*1303 can be defined structurally.

Alleles↗
PubMed1991

[Influence of HLA compatibility on cytomegalovirus infection in kidney transplantation].

The influence of HLA A, B, DR on the incidence and symptoms of cytomegalovirus (CMV) infection was investigated in 143 patients who, between October 1st, 1987 and December 31st, 1989, received kidneys from cadaveric donors. Systematic virological monitoring was carried out weekly during the first hospitalization and thereafter at each new hospitalization or in the presence of clinical signs suggestive of viral infection. The diagnosis of CMV was based on positive isolation in blood or urine, or seroconversion, or 4-dilution rise in the anti-CMV antibodies titre. HLA grouping of all recipients was made in the same histocompatibility laboratory. Immunosuppression was obtained with a quadruple therapy consisting of corticosteroids (15 mg/kg before transplantation, then 1 mg/kg for 10 days, then gradually tapering off dosage), azathioprine (2 to 3 mg/day), cyclosporin A (2 mg/kg i.v. followed by an oral dose adjusted to the residual levels) and a randomized treatment with either monoclonal anti-CD3 antibody or anti-thymocyte globulins administered during the first 10 days. The incidence of CMV infection was 56 percent (80/143), with 25 percent of primary infection (20/80). The number of DR compatibilities was found to have a significant influence on the incidence of CMV infection, which rose from 22 to 50 and 65 percent respectively in the group of patients with 2.1 or 0 DR compatibility (P less than 0.02). The degree of B + DR compatibility was also associated with the occurrence of CMV infection, the incidence of which rose from 0 to 36, 59, 43.5 and 71 percent respectively in the group of patients with 4, 3, 2, 1, 0 B + DR compatibility (P less than 0.03). The incidence of primary CMV infection increased with the number of DR incompatibilities, rising from 0 to 29 and 52 percent respectively in the group of patients with 0, 1 or 2 DR incompatibilities. The symptoms and severity of CMV infection were significantly influenced by the degree of DR and B + DR compatibility. Despite a very strong association between graft rejection and CMV infection (P less than 0.000001), no influence of HLA, and particularly DR or B + DR compatibility on the incidence and number of graft rejections could be demonstrated. It is concluded that, under the above-described quadruple therapy, the HLA DR and B + DR compatibility exerts a predominant influence on the occurrence and severity of CMV infection, and that this effect is independent of any action on graft rejection.(ABSTRACT TRUNCATED AT 400 WORDS)

Cytomegalovirus Infections↗
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

New developments in stem cell transplantation with special reference to the first in utero transplants in humans.

Based on the experience acquired in post-natal liver transplantation since 1974, we recently initiated pre-natal, in utero stem cell transplantation from the human fetal liver. The first two fetuses that we treated had immunodeficiencies, the third one had thalassemia major. Donors and recipients were not matched. The fetal cells were infused in the umbilical vein of the first two patients and injected intraperitoneally into the third one, under ultrasonic visualization. The first patient, born in 1988, has both engraftment of donor cells and reconstitution of cell-mediated immunity. This child, who had bare lymphocyte syndrome, has no clinical manifestation of the disease and he lives normally at home. The second child, born in 1989, has not yet developed a significant reconstitution of immunity although donor cell engraftment has been proven (Y chromosome in this female patient). The third patient has also evidence of donor cell take (Y chromosome in a female patient) but the effect on thalassemia has not yet been fully analyzed (donor hemoglobin present in small quantity). In all 3 cases, no side-effect of any kind developed in the mother nor in the fetus. Several advantages appear to be associated with in utero FLT: increased probability of graft take, ideal isolation of patient (in the uterus), optimal environment for fetal cell development (in the fetal host).

Female↗
PubMed1989

DNA typing of DRw6 subtypes: correlation with DRB1 and DRB3 allelic sequences by hybridization with oligonucleotide probes.

Among MHC class II antigens, the DRw6/Dw6 complex represents a special situation where typing on a routine basis is often troublesome, mainly because monospecific alloantisera are rare and individual subtypes numerous. We demonstrate here that the use of oligonucleotide DNA typing permits an analysis of the polymorphism within DRw6 haplotypes and provides a molecular basis for correlations with functional data. Synthetic oligonucleotide probes, most of them locus- and allele-specific, were derived from the DNA sequences of three alleles of locus DRB1 and three alleles of locus DRB3. These probes allow the positive identification of distinct DRw6 subtypes. As analyzed on a panel of 26 well-defined DRw6 cell lines, oligotyping allows a direct and absolute correlation with the DRw13 serologic specificity and with the cellularly defined Dw9,Dw16,Dw18, and Dw19 specificities. Correlations of the polymorphism at the DRB1 locus with the polymorphism at the DRB3 locus (DRw52 alleles) allow us to identify preferential allelic associations such as DRw13-Dw18-DRw52a/52b, DRw13-Dw19-DRw52c, and DRw13/Dw19 haplotype, the Dw19 cellular reactivity might involve, at least DRw14-Dw9-DRw52b. In view of the absolute segregation of the DRw52c allele with the DRw13/Dw19 haplotype, the Dw19 cellular reactivity might involve, at least in part, epitopes on the DRw52c allele. The identification of DRw6 subtypes, as well as of other HLA class II subspecificities, by oligotyping can now complement and possibly replace serologic and cellular typing. It represents a particularly useful contribution to the optimization of class II matching in the case of bone marrow transplantation with unrelated donors.

Alleles↗
PubMed1989

Prenatal treatment in congenital adrenal hyperplasia due to 21-hydroxylase deficiency: up-date 88 of the French multicentric study.

A multicentric study of prenatal treatment of congenital adrenal hyperplasia (CAH) resulting from 21-hydroxylase deficiency in 43 pregnancies at risk for CAH is presented. The mothers were given dexamethasone per os, 0.5 mg either 12-hourly or 8-hourly. From the analysis of the results obtained in the present study and review of the literature, it would appear that the first condition for successful prevention of female virilization in utero (a total of 6 cases) is to start treatment as early as possible, no later than the 7th week. The dose of dexamethasone should be related to maternal size: 20 micrograms/kg/day (in 2 or 3 fractioned) doses would seem to be both efficient and safe. Adrenal suppression of both maternal and fetal adrenal function should be controlled by appropriate hormonal determinations. Finally, the advantages of early prenatal diagnosis or no prenatal diagnosis are discussed.

Adrenal Hyperplasia, Congenital↗
PubMed1989

A method of HLA class II typing using nonradioactive labelled oligonucleotides.

The typing of HLA class II genes using molecular biology techniques has brought undoubtedly new insights in the analysis of their polymorphism. Particularly interesting is the dot-blot analysis of enzymatically-amplified genomic DNA hybridized with sequence-specific oligonucleotides. In order to use this technique of typing on a routine basis, we established a non-radioactive detection method of enzymatically-amplified genomic DNA dot-blots. We could clearly demonstrate that, using biotin-labelled specific oligonucleotides, it was possible to specifically discriminate between DQB1 first domain DNA sequences displaying three, two or even only one base-pair difference at a given codon position. The very satisfactory sensitivity level reached by this non-radioactive detection method could safely allow its use for clinical applications of HLA typing at the DNA level.

DNA↗
PubMed1989

Rearrangements and point mutations of P450c21 genes are distinguished by five restriction endonuclease haplotypes identified by a new probing strategy in 57 families with congenital adrenal hyperplasia.

Congenital adrenal hyperplasia (CAH) is caused by disorders of the P450c21B gene, which, with the P450c21A pseudogene, lies in the HLA locus on chromosome 6. The near identity of nucleotide sequences and endonuclease cleavage sites in these A and B loci makes genetic analysis of this disease difficult. We used a genomic DNA probe that detects the P450c21 genes (A pseudogene, 3.2 kb; B gene, 3.7 kb in Taq I digests) and the 3' flanking DNA not detected with cDNA probes (A pseudogene, 2.4 kb; B gene, 2.5 kb) to examine Southern blots of genomic DNA from 68 patients and 165 unaffected family members in 57 families with CAH. Of 116 CAH-bearing chromosomes, 114 could be sorted into five easily distinguished haplotypes based on blots of DNA digested with Taq I and Bgl II. Haplotype I (76 of 116, 65.6%) was indistinguishable from normal and therefore bore very small lesions, presumably point mutations. Haplotype II (4 of 116, 3.4%) and haplotype III (8 of 116, 6.9%) had deletions and duplications of the P450c21A pseudogene but had structurally intact P450c21B genes presumably bearing point mutations; point mutation thus was the genetic defect in 88 of 116 chromosomes (75.9%). Haplotypes IV and V lack the 3.7-kb Taq I band normally associated with the P450c21B gene. Haplotype IV (13 of 116, 11.2%) retains all other bands, indicating that the P450c21B gene has undergone a gene conversion event, so that it is now also associated with a 3.2-kb band. Haplotype V (13 of 116, 11.2%) lacks the 2.4-kb Taq I fragment and the 12-kb Bgl II fragments normally associated with the P450c21A pseudogene, as well as lacking the 3.7-kb Taq I fragment, indicating deletion of approximately 30 kb of DNA, resulting in a single hybrid P450c21A/B gene. Most (114 of 116, 98%) CAH alleles thus can easily be classified with this new probing strategy, eliminating many ambiguities resulting from probing with cDNA.

Adrenal Hyperplasia, Congenital↗
PubMed1989

HLA class II antigens: structure, function, and expression in immunodeficiencies, autoimmune diseases, and allograft rejection.

The major histocompatibility complex (MHC) genes, coding for the histocompatibility leukocyte antigens (HLAs) are located on the short arm of chromosome 6. The HLA gene products are involved in many immune responses. Class I and class II molecules are composed of two subunits. Class I antigens are expressed on all cell types except red blood cells; class II molecules have a more limited distribution and are found only on certain cell types. A review of our current knowledge of the genes coding for these molecules, their biochemical analysis, and the current investigation into the three-dimensional structure of the glycoproteins will allow us to understand better how this complex system, which has been preserved in animal species throughout the evolutionary process, operates. The biologic significance of HLA class I and class II molecules in the development of an efficient immune system that permits our survival in the sea of microorganisms in which we are immersed is illustrated by the severe and lethal infections that occur when these antigens are absent. Important and interesting variations in class II antigen expression are also observed in certain autoimmune diseases. Furthermore, the role of these antigens in the allogeneic reaction of graft rejection has now been clearly identified. It has become increasingly apparent how important it is to understand the antigenic variation between organs, or even between cells within an organ, and to be able to identify the circumstances that are associated with modulation of antigen expression.

Autoimmune Diseases↗
PubMed1988

Islet cell and insulin autoantibodies in subjects at high risk for development of type 1 (insulin-dependent) diabetes mellitus: the Lyon family study.

Genetic determination as well as prospective analysis of islet cell autoantibodies and autoantibodies to insulin were conducted in a population of 479 first degree relatives of 174 Type 1 (insulin-dependent) diabetic patients. Analysis of HLA haplotypes within families illustrated the high frequency of DR3 and DR4 alleles with preferential transmission from parent to both affected and unaffected offspring. DR4 was preferentially associated with DQw3.2 (TA10-) in 60/73 (82.2%) patients and 101/127 (79.5%) relatives. Relatives have been followed for a period of 800 subject-years. Twenty-two out of 430 relatives (5.1%) were found islet cell antibodies (ICA-IgG) positive. Seven sera with low titres became negative 6 months later at two different determinations. Fifteen sera ICA-IgG and ICA-protein A positive with high titres remained positive thereafter. Half of the ICA positive relatives were also found insulin autoantibodies (IAA) positive. All but 3 ICA negative relatives did not have IAA in their sera. Analysis of IAA specificity with competition experiments indicated that most antibodies recognised epitopes shared between human and pork insulins while four were specific for human insulin determinants. Analysis of class I and class II HLA antigen distribution indicated no particular allelic restriction in antibody positive individuals. Metabolic status of antibody positive relatives was determined with oral and intravenous charge of glucose. Two haplo-identical DR3-DQw2 brothers became diabetic during the study. One child and one mother both with DR4-DQw3.2 became intolerant to glucose. Each of these relatives had high titre ICA prior to metabolic deterioration.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

[Absence of HL-A homology in couples presenting repeated miscarriages. Trials with multidonor transfusions].

Maternal tolerance of the fetus involves maternal immuno-regulating mechanisms. The genetic control of this immune response depends on the HL-A system. An extreme HL-A antigenic community between parents might cause a decreased immune response and increased miscarriages. Contrary to some studies from the literature, in our experience, HL-A homology in couples with recurrent miscarriages does not seem significant. This absence of homology may be explained by an extreme polymorphism of HL-A antigens identified and isolated every year. The role of maternal blocking antibodies in maternal tolerance of the fetus is also discussed. The results of a protocol of multi-donor transfusions in 8 patients, is presented and reviewed according to the resulting pregnancies and data from the literature.

Abortion, Habitual↗
PubMed1987

Particular interest of HLA typing for genetic counselling in families with congenital adrenal hyperplasia (21-OH deficiency).

The close genetic linkage between 21 hydroxylase deficiency and HLA loci considerably enlarges the possibilities of genetic counselling. Two 21-OH deficient complex families are reported, illustrating several aspects of this genetic counselling: detection of carriers, determination of the actual risk to related couples, suspicion of 21-OH deficiency by an HLA specificity association, and prenatal diagnosis.

Adrenal Hyperplasia, Congenital↗