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Biomedical subjects

M Drouet

Publications and source records attributed to M Drouet.

At least 19 recordsLinked to original sources
PubMed2000

Ex vivo expanded mobilized peripheral blood CD34+ cells accelerate haematological recovery in a baboon model of autologous transplantation.

To address the value of ex vivo expanded haematopoietic cells for shortening cytopenia in autologous haematopoietic transplantation, we designed an ex vivo expansion protocol based on a cocktail of early acting cytokines and short-term culture and tested it in a baboon model. Expansion involved enriched CD34+ peripheral blood haematopoietic cells cultured for 6 d with a combination of FLT3-L, stem cell factor (SCF), thrombopoietin (TPO) and interleukin (IL)-3 (50 ng/ml each); CD34+ cells, granulocyte-macrophage colony-forming units (GM-CFU) and megakaryocytic colony-forming units (MK-CFU) were amplified, respectively, 10.5-, 20.5- and 17.9-fold. Baboons were submitted to a myeloablative regimen consisting of cyclophosphamide plus total body irradiation (TBI; 6 Gy) and were then grafted with either 2 x 106/kg unmanipulated CD34+ cells (control group, n = 4) or cells cultured from 2 x 106/kg CD34+ cells (expansion group, n = 4). No cytokines were administered after transplantation. All the animals engrafted. The mean times to white blood cell (WBC), granulocyte and platelet recovery were significantly shorter in the expansion group than in the control group: WBC (> 1 x 109/l) and neutrophil (> 0.5 x 109/l) recovery occurred on days 8 (range 6-9) and 9 (range 6-11), respectively, compared with days 12 (range 10-15) and 14 (range 11-16); platelets recovered (> 20 x 109/l) on day 9 (range 7-12) compared with day 13 (range 11-15) in the control group (P < 0.05). No toxicity was observed after reinfusion. No secondary hypoplasia was observed during more than 12 months of follow-up. Functions of both neutrophils and platelets produced from expanded cells were normal in terms of oxidative metabolism, chemotaxis and the bleeding time. This study shows that in comparison with unmanipulated cells peripheral blood haematopoietic cells expanded from similar doses of CD34+ cells, under the conditions defined here, accelerated both neutrophil and platelet recovery without impairing long-term haematopoiesis.

Animals↗
PubMed2000

Diagnosis of venom allergy by flow cytometry. Correlation with clinical history, skin tests, specific IgE, histamine and leukotriene C4 release.

BACKGROUND: Potent allergens such as hymenoptera venoms are capable of inducing severe and life threatening clinical reactions. Percentage of false negative results obtained by the usual diagnostical methods is comprised between 10 and 25%. OBJECTIVE: Evaluation of the sensitivity and the specificity of cellular tests and particularly evaluation of a new flow cytometric method. METHODS: Forty-five allergic patients having experienced a local, a systemic reaction or an anaphylactic shock and 10 controls having undergone hymenoptera stings without clinical reactions were selected on the basis of the clinical history, skin tests and specific IgE. Three cellular tests were performed on the same cell suspensions and in the presence of 2 ng/mL of rIL3: histamine release (RIA), leukotriene C4 release (ELISA) and basophil activation test (flow cytometry after double anti-IgE FITC, anti-CD63 PE labelling). RESULTS: As compared to the clinical history, sensitivities of skin tests, specific IgE, flow cytometry, histamine release and leukotriene release were, respectively; 85%, 88%, 100%, 89% and 100%. Flow cytometric analysis of basophil activation showed a significant decrease of the mean fluorescence density and number of IgE positive cells and a significant increase of the number of CD63 positive cells. The 10 controls tested by flow cytometry were negative. CONCLUSION: As compared to the clinical history and to the other parameters tested here, flow cytometry showed a high sensitivity and a high specificity. The excellent correlation observed between this method and the other cellular tests such as histamine and leukotriene release are in favour of the specificity of flow cytomery and in favour of the use of this method for venom allergy diagnosis.

Adolescent↗
PubMed2000

CTLA4 exon 1 dimorphism in bullous and cicatricial pemphigoid.

The human cytotoxic T-lymphocyte antigen 4 (CTLA4) gene encodes proteins regulating the immune response. The polymorphism of this gene is associated with some autoimmune diseases. In this study, we analysed the distribution of the dimorphisms of exon 1 (+ 49 A/G) in bullous pemphigoid (BP) and cicatricial pemphigoid (CP), two types of autoimmune bullous skin diseases that occur in elderly people. The frequency of the exon 1 A-G genotype was marginally decreased in patients (36.4%; n = 55) compared with controls (52.8%, n = 53), but the results were not statistically significant (P = 0.09).

Abatacept↗
PubMed2000

Alleles of the alpha1 immunoglobulin gene 3' enhancer control evolution of IgA nephropathy toward renal failure.

BACKGROUND: IgA nephropathy is the most common glomerular disease. Mechanisms leading to its occurrence and controlling the evolution of the disease remain largely unknown. Various genetic factors have been found, mostly implicating immunologically relevant genes (IgH, TCR, human lymphocyte antigen, and complement loci). A regulatory region recently identified downstream, the alpha1 gene of the IgH locus, was a likely candidate for the control of IgA1 production in patients. Alleles of this region, differing by size, sequence, and orientation of the alpha1 hs1,2 transcriptional enhancer, were first identified through Southern blot hybridization. METHODS: We established a polymerase chain reaction (PCR) method suitable for routine testing that amplifies minisatellites within the alpha1 hs1, 2 enhancer, with variable numbers of tandem repeats (VNTR) defining the two alleles. This assay allowed the typing of 104 patients with IgAN and 83 healthy volunteers. Results from typing of alpha1 hs1,2 alleles were compared with long-term clinical outcome in patients. Enhancer alleles were compared in a luciferase reporter gene assay. RESULTS: The alpha1 hs1,2 alleles do not constitute a predictive factor for IgA nephropathy, since similar allelic frequencies were observed in healthy individuals and in unrelated European patients. In contrast, among patients, homozygosity for the weakest enhancer allele (AA genotype) was significantly correlated with a milder form of the disease, whereas the allele B was associated with severe evolution. The minisatellite region within the alpha1 hs1,2 enhancer carried potential transcription factor-binding sites, and its duplication increased the transcriptional strength of the alpha1 hs1, 2 allele B over that of allele A. CONCLUSION: Altogether, these alleles may constitute a risk factor for the prognosis of IgA nephropathy.

3' Untranslated Regions↗
PubMed2000

[The wasp-mosquito syndrome: extension of cross-allergenicity to the horsefly].

The crossed allergenicity between wasp venom and mosquito extract was shown during recent work based on clinical observations and correlation studies between different biological parameters, indicating an IgE-dependent biological mechanism. A common protein was identified by Immunoblot. From observation of one of our patients involved in this work, we examined the possibility of the extension of crossed reactivity between wasp, mosquito and horsefly. In effect, our patient presented an anaphylactic reaction with neurological complications from attack on the central grey nucleus, shown by IRM; the immunological study showed a common protein between wasp venom and the total extracts of mosquito and horsefly.

Adult↗
PubMed1999

The reduction of in vitro radiation-induced Fas-related apoptosis in CD34+ progenitor cells by SCF, FLT-3 ligand, TPO, and IL-3 in combination resulted in CD34+ cell proliferation and differentiation.

Recovery from radiation-induced (RI) bone marrow aplasia depends on appropriate cytokine support. The early effects of exogenous cytokines at the hematopoietic stem and progenitor cell (HSPC) level following irradiation are still largely unknown, especially those of survival factors such as stem cell factor (SCF) and Flt-3 ligand (FL). This study was aimed at A) clarifying Fas/Fas-Ligand (Fas-L) implication in RI apoptosis of CD34+ cells and B) assessing the capacity of a combination of cytokines to mitigate RI apoptosis in HSPCs in vitro. We showed that most of in vitro gamma-irradiated CD34+ HSPCs incubated in a medium devoid of cytokines underwent progressive apoptosis-related changes from 6 h (i.e., decreased CD34 antigen expression, Annexin V binding); then Fas/Fas-L coexpression occurred from 10 h on. A strong DNA fragmentation, as assessed by TUNEL assay and propidium iodide staining, was observed at 24 h. Within a 2.5- to 6-Gy dose range, the RI apoptotic process finally led to 97% CD34+ cell death within 48 h with a complete loss of functionality. Unirradiated cells incubated in the same conditions displayed a significantly reduced apoptotic pattern. The early addition of a combination of SCF, FL, thrombopoietin, and interleukin 3 (4F) after cell irradiation prevented 15% (2.5 Gy) and 12% (4 Gy) of HSPCs, respectively, from RI apoptosis, whereas these cytokines used as single factors were inefficient. Furthermore, irradiated HSPCs (2.5 Gy) incubated with 4F in a serum-free culture system for seven days proliferated, giving rise to an increase in the number of total cells (x5.6-fold) and CD34+ cells (x4.2-fold) and to megakaryocytic and granulomonocytic precursors. These results show that the prevention of apoptosis in in vitro irradiated HSPCs depends on an early combination cytokine support. These data suggest that the early therapeutic administration of anti-apoptotic cytokines may be critical for preserving functional HSPCs from in vivo radiation damage.

Animals↗
PubMed1999

Optimisation of HLA-B27 testing by association of flow cytometry and DNA typing.

HLA-B27 typing contributes to the diagnosis of ankylosing spondylitis. The classical technique of microlymphocytotoxicity is costly and can give false-negative results. We have compared 304 samples using two relatively new methods - flow cytometry and PCR-SSP - and evaluated their respective uses in routine analysis. Flow cytometric HLA-B27 testing was performed using three monoclonal anti-B27 antibodies (HLA-ABC-m3, GS145.2 and FD705 clones). Cut-off values were established to differentiate HLA-B27-positive from HLA-B27-negative samples with ROC curves. Although flow cytometric analysis with a reliable monoclonal antibody (mAb) is valuable for HLA screening, none of the HLA-B27 flow cytometry protocols was sufficient on its own to ascertain the HLA phenotype in 100% of samples. Two false negatives were observed with the FD705 mAb and the use of two different monoclonal antibodies did not increase the accuracy of HLA-B27 typing. HLA-B27 typing using molecular biology is a reliable but costly technique. Therefore we suggest that DNA typing could be used as a complementary technique and applied to samples whose HLA-B27 phenotype cannot be determined by flow cytometry. The association of flow cytometry and DNA typing is, in our experience, an economical and reliable approach.

Antibodies, Monoclonal↗
PubMed1999

Age-associated changes in mitochondrial parameters on peripheral human lymphocytes.

Among theories of aging, mitochondria are believed to be involved in senescence. Alterations of respiratory chain function and accumulation of various mitochondrial DNA mutations have been reported in mammalian postmitotic tissues. Because mitochondria have a central role in apoptosis and in adenosine triphosphate production, alteration of mitochondria function could contribute to immune senescence. We searched for alterations of mitochondrial parameters in peripheral lymphocytes with aging. Comparisons of respiratory chain activities of complex II+III, III, and IV were carried out in two populations of healthy volunteers with average ages of 35.3 +/- 6.7 years and 80.8 +/- 8.7 years. No difference was observed in complex IV activity between each group, whereas a significant decrease of complex II+III and a nonsignificant decrease of complex III activity were observed with aging. Alterations in mitochondrial functions can result from mutations in mitochondrial DNA (mtDNA), the most common being the 4977-bp deletion (mtDNA(-4977)). In either group we observed many deletions of mtDNA on peripheral blood lymphocytes by large-fragment polymerase chain reaction. This result suggests that alterations of respiratory chain activities observed with aging in lymphocytes could be the result of nuclear DNA dysfunction, with consequences on immune function (reduced responsiveness to antigen). Its possible implication on the recent observation of increased apoptosis of CD45RA+ RO- T cells with aging is discussed.

Adult↗
PubMed1999

HLA-G and classical HLA class I transcripts in various components of the adult human eye.

HLA-G transcripts have previously been detected in the ocular cell line HS738, in foetal eyes and in global ocular extract. Using RT-PCR and hybridization, we searched for HLA-G and classical HLA class I transcripts in the corneas of eye donors (n = 6) and in various components of eyes collected at time of surgery: lens (n = 3), iris (n = 2), vitreous body (n = 2) and retina (n = 2). Whereas HLA class I mRNA was abundant in the ocular tissues of all donors, we could not find HLA-G transcript in any ocular tissues obtained from subjects in vivo. The absence of HLA-G in adult eye cornea limits its interest as a possible target in corneal transplantation. Classical HLA class I transcripts were abundant in the cornea and other components of the eye. These results highlight the role of classical HLA class I antigen in eye immunity and corneal transplantation.

Cornea↗
PubMed1999

Age-related alterations of somatic hypermutation and CDR3 lengths in human Vkappa4-expressing B lymphocytes.

The lower avidity and/or affinity of antibodies generated by an aged immune system could be attributed to two major changes in the antibody repertoire: a shift in germline gene usage and a decrease in the rate of immunoglobulin hypermutation. In an attempt to identify the mechanisms involved in the observed humoral immune deficiency in the elderly, we studied whether differences in the somatic diversity of a particular Vkappa region occurred with ageing. By using the polymerase chain reaction and sequencing, we analysed and compared Vkappa4-Jkappa rearrangements isolated from young (mean age 21 years) and aged (mean age 83 years) healthy adults. Mutations in the Vkappa4 gene compared with the germline sequence were determined as well as the length and structure of the CDR3 sequence. We analysed in detail various mechanisms contributing to CDR3 and Vkappa variability in rearrangements involving the Vkappa4 gene. Our data revealed that, despite strong individual variations, significantly lower levels of somatic mutation were found in the aged group, both for complementarity-determining regions (CDRs) and framework regions (FRs) encoding Vkappa4 sequences. This decrease mostly affected mutations responsible for replacements and thus resulted in a lowered somatic diversification of the encoded Vkappa4 proteins in aged individuals. Moreover, comparison of the CDR3 regions of the Vkappa4-Ckappa cDNA revealed changes in light-chain junctional diversity that correlated with age. Altogether these data suggest an impaired light-chain somatic diversity in connection with human senescence.

Adult↗
PubMed1999

Interleukine-8 acts as a strong peripheral blood granulocyte-recruiting agent rather than as a hematopoietic progenitor cell-mobilizing factor.

Intravenous infusion of Interleukine-8 has been shown to lead to a rapid mobilization of hematopoietic cells in mice and rhesus monkeys. We report in this study that the IL-8-mediated mobilizing effect results in low levels of circulating CD34+ cells, whereas a rapid and strong recruitment of mature granulocytes occurs. This would be of great interest for harvesting large numbers of functional granulocytes to fight infection in immunodepressed patients. We performed a kinetic study of the mobilization in a nonhuman primate model (Papio ursinus), mobilized with a single or double infusion of IL-8 with a dose range of 30-50 microg/kg of body weight. Blood was sampled every 15 min after the IL-8 infusion, and IL-8 plasma levels, complete blood counts, differential WBCC, colony-forming unit assays, and CD34+ cell evaluation assays were performed. At the same time, leukapheresis was performed on the anesthetized animal to collect either hematopoietic stem and progenitor cells (HSPC) or peripheral blood granulocytes (PBG) according to different collection settings. IL-8 induced a rapid increase of PBG (7-12-fold the basal values). The HSPC leukapheresis concentrate showed poor ex vivo expansion abilities. IL-8-mobilized peripheral blood polymorphonuclear cells showed normal oxidative, chemotactic, phagocytic, and adherence abilities. We suggest that IL-8-induced neutrophilia could be used as an allogeneic source of granulocytes for transfusion in neutropenic patients or in granulocyte dysfunction.

Animals↗
PubMed1999

[Search for a threshold to distinguish between locoregional and systemic reactions using the histamine liberation value and the LTC4 level].

Allergy to Hymenoptera venom (VH) effects more and more patients in France. It is manifest in two main forms, which are Loco-regional (RLR) and Systemic reactions (SR). This allergy is detectable amongst others by the techniques of histamine release (HR) and release of leucotrienes C4 (LTC4). The aim of this work has been to fix a threshold that gives differentiation of RLR ad RS by the two techniques. We found in a positive population a threshold histamine release (HR) value of 25% and a concentration of LTC4 of 600 ng/ml. These are the thresholds above which a patient would be at around 70% risk of RS. This study has a predictive value for patients who are suspected of allergy of VH or who have already had clinical reactions and risk sensitization.

Acetylcholinesterase↗
PubMed1999

[Basophil activation test using flow cytometry in Hymenoptera venom allergy].

The basophil activation test (TAB) clearly shows evidence to Hymenoptera venoms. Comparison of the TAB value with the clinical history allows fixation of a threshold that will anticipate the type of clinical reaction by the TAB value. For the technique of TAB 3 dilutions are used. The basophil activation values produce a threshold for each dilution. For the first dilution the threshold is 50% activation: below this threshold, 70% of patients would have a local or systemic reaction and above this threshold, 70% of patients would have a systemic allergic reaction.

Adult↗
PubMed1999

[Level of histamine in supernatants from the basophil activation test: applications to hymenoptera allergy and drug allergy--preliminary study].

Histamine Release technic consists in calculating histamine liberated by blood cells in touch with an allergen. To this day, this method is only used in Hymenoptera venom allergy diagnosis. The principle of this study is to measure histamine released by activated basophils in surnageons of Basophil Activation Test (BAT) for different allergens: Hymenoptera venoms: Bee, White Faced Hornet, Vespula Wasp. Drugs: Cefaperos, Clamoxyl, Alfatil, Rapifen, Diprivan, Nesdonal, Mivacron. A threshold of positivity (amplification factor in comparison with the control) is determined for these two classes of allergens: 45 for Hymenoptera venoms and 9 for drugs. These results, compared to the other diagnosis technics (Histamine Release, Basophil Activation Test, Prick Tests) discloses very high correlation rates in each case. This method seems to be a reliable method for Hymenoptera venom allergy diagnosis and for drugs allergy diagnosis too. However, this study is based on a few number of patients, so a significant statistic conclusion can't be expressed but it opens an interesting way of research.

Basophil Degranulation Test↗
PubMed1999

[Chronic urticaria caused by cow's milk allergy: immediate or delayed allergy? (apropos of a case)].

Chronic urticaria has multiple etiologies, amongst them food allergy, which is not the most frequent. We report a clinical case of chronic urticaria due to cow milk, where paradoxically the responsibility of the food was shown by an epidermo test when the prick test was negative. Development confirmed the responsibility of cow milk. We discuss the mechanisms that relate chronic urticaria to delayed hypersensitivity.

Adult↗
PubMed1999

[Membrane stabilizers (chromones and ketotifen)].

The drugs called "Membrane stabilisers" are composed of cromones (sodium cromoglycate and nedocromil) and Ketotifen. They inhibit the degranulation of mastocytes by a membrane stabilising effect. Ketotifen is distinguished from the cromones by a conjoint antihistamine effect. Nowadays, the indications are for prophylactic treatment of allergic asthma, rhinitis and allergic conjunctivitis and the manifestations of food allergy. Therapeutic efficacy seems to be good in intermittent or mildly persistent asthma, especially in children or young subjects. Secondary effects are rare and generally benign, with reduced contra-indications.

Animals↗
PubMed1999

[Anti-histamines].

The use of anti-histamines remains the therapy of choice for the ensemble of allergic pathologies with a reaginic mechanism. Knowledge of the metabolism of histamine gives an understanding of a number of allergic symptoms and also clarifies the mechanism of action of the anti-histamines. Many molecules are appearing on the market, each with a more precise action on the specific H1 receptors and also carrying other pharmacological specificities of better and better study. Observance of contra-indications, in particular cardio-vascular, allows their use without reserve, whilst knowing that there are always problems of specific tolerance, that are variable from one individual to another, specially on drowsiness. The importance of stopping anti-histamines must be remembered, every time that this is possible, before making an allergic diagnosis by skin tests.

Animals↗