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Biomedical subjects

F Marchand

Publications and source records attributed to F Marchand.

29 records · Page 2Linked to original sources
PubMed1992

Identification of allergenic epitopes on Der f I, a major allergen of Dermatophagoides farinae, using monoclonal antibodies.

The antigenic and allergenic structure of Der f I, a major allergen of the house dust mite Dermatophagoides farinae (Df) was investigated by means of a panel of 11 selected monoclonal antibodies (mAb) obtained from BALB/c mice immunized with purified Der f I. The species specificity of these mAb, tested with Der f I and Der p I--the homologous allergen from Dermatophagoides pteronyssinus--was generally restricted to Der f I since 10 out of 11 mAb reacted only with this allergen. Epitope specificity of the mAb was determined by both competitive inhibition and sandwich ELISA experiments. The results indicated the presence of at least four non-overlapping, non-repeated antigenic sites on Der f I, which were recognized by one or several mAb (sites A, B, C and D). Comparative epitope specificity studies between human IgE antibodies and mice mAb were performed, on sera and basophils of Df sensitive patients, using different inhibition assays (ELISA and histamine release experiments). The degree of inhibition varied between the patients and upon the assay design. Most of the mAb tested were found to significantly inhibit the binding of human IgE to Der f I (p less than 0.01) when compared with Der p I specific mAb as a control. The mAb reacting with site A was found to be the most potent inhibitor, presenting a mean inhibition of up to 56% in ELISA as well as in histamine release experiments. The results show that both human IgE antibodies and mAb can be directed against identical or closely related epitopes of Der f I. Therefore anti-Der f I mAb constitute immunologic probes in further allergenic epitope and peptide analysis of this major mite allergen.

Allergens↗
PubMed1990

Investigation of the laminate structure of lumbar disc anulus fibrosus.

The structure of the lumbar disc anulus fibrosus was investigated using a layer-by-layer peeling technique and microscopic examination of various cut surfaces. Anulus specimens from spines of two different age groups and from two levels, L2-3 and L4-5, were examined. The vertebra-disc-vertebra units were subjected to intentional controlled dehydration to enhance the visual contrast between the white opaque fiber bundles and the translucent ground substance. The variations of the anulus structure with circumferential and radial locations were studied. The following principal structural features were quantified: 1) the anulus, excluding the transition zone, consists of 15 to 25 distinct layers, depending on the circumferential location, the spine level, and the specimen age; 2) in any 20 degrees circumferential sector, nearly half of the layers terminate or originate, thereby causing local laminate irregularities; 3) there are two identifiable mechanisms of layer interruption at these irregularities; 4) the thickness of individual layers varies both circumferentially and radially and increases markedly with age; and 5) the number of fiber bundles over the total height of the disc varies from 20 to 62, with an average interbundle spacing of 0.22 mm.

Adult↗
PubMed1989

Enhancement of the histamine releasing activity of mouse monoclonal anti-human IgE antibody xb6-16 when present in aggregated or complexed forms.

FPLC purification of mouse monoclonal anti-human IgE antibody xb6-16 showed 2 major peaks of different molecular weight, peak 1 (greater than 10(6) d) and peak 3 (1.6 x 10(5) d). Peak 1 consisted of IgG1 and IgM, peak 3 of IgG1 only. On a protein weight basis, peak 1 was 100 times more potent than peak 3 in inducing histamine release from human basophils. Preincubation of peak 3 with anti-IgG1 enhanced the mediator release triggered by this fraction. On this basis, the potentiating effect of aggregated IgG1 or IgG1-IgM complexes on mediator release from basophils is discussed.

Animals↗
PubMed1987

Monoclonal anti-human IgE: histamine release capacity and effect on in vitro sensitization of human basophils.

IgE-anti-IgE complexes were formed by preincubation of a human myeloma IgE with a monoclonal anti-human IgE antibody at different concentrations. Binding of IgE onto the anti-IgE inhibited the histamine release capacity of anti-IgE from basophils. The IgE cell-binding capacity was altered by the IgE/anti-IgE ratio in the preincubation buffer. Heating of the complexes gave a partial recovery of the anti-IgE degranulation capacity, suggesting that the monoclonal anti-IgE is specific for an epitope present on the D epsilon 2 domain.

Antibodies, Anti-Idiotypic↗
PubMed1987

Basophil sensitivity and reactivity to monoclonal anti-human IgE after in vitro sensitization with human myeloma IgE.

Leucocytes from human peripheral blood were acid eluted and sensitized in vitro with increasing concentrations of radiolabelled myeloma IgE. This sensitization step was performed with or without 30% IgE depleted serum. After the IgE binding, cells were washed and submitted to a challenge with monoclonal anti-IgE for the determination of the cellular sensitivity and reactivity in a histamine release assay. A sample of each of the sensitized cells was analyzed for its radioactivity and the number of basophils quantified, thus allowing the determination of the mean number of IgE molecules per basophil. Raising the IgE concentrations in the sensitization procedure led to an increase of the IgE on the basophil membrane, and to a concomitant elevation of the cell sensitivity. The presence of serum during the binding of IgE onto the cells lowers slightly the binding of IgE to the basophils but decreases strongly the cellular reactivity.

Antibodies, Anti-Idiotypic↗
PubMed1986

Passive in vitro sensitization of human basophils with Dermatophagoides farinae specific IgE.

Basophils from allergic or non-atopic donors were depleted for their native membrane IgE by acid treatment and then passively sensitized by Dermatophagoides farinae specific IgE containing sera. Histamine release experiments were performed with a highly purified allergen (Df 11) on native cells, acid treated cells and passively sensitized cells. In the sensitization procedure, the quantity of the basophil-bound serum IgE is dependent on the concentration of the sensitizing serum IgE and the histamine release capacity is specifically acquired. It is shown that after passive sensitization basophil membrane IgE density as well as basophil sensitivity to Df 11 in histamine release experiments depend on the ratio [Df 11 specific IgE/total IgE] in the sensitizing serum.

Allergens↗
PubMed1986

Thermoinactivation of human IgE: antigenic and functional modifications.

The thermoinactivation kinetics of IgE were studied in experimental models revealing the antigenic properties and the basophil-sensitizing capacity of these immunoglobulins. A pool of human sera containing anti-Dactylis glomerata (Dg) IgE was heated from 5 min up to 4 hr at 56 degrees. The IgE antigenicity was tested by two polyclonal 125I-labelled anti-IgE antibodies; one anti-IgE was specific of the whole Fc epsilon region, while the other had a specificity restricted to the D epsilon 2 domain. Radioimmunoassays showed that the D epsilon 2 epitopes were more rapidly altered than the D epsilon 1 epitopes. The capacity of IgE to bind to basophil Fc epsilon receptors was assayed by passive sensitization experiments. Basophil sensitivity towards the Dg pollen extract was tested by histamine release experiments in the presence of this allergen. A progressive decrease in cell sensitivity was observed when IgE samples used for cell sensitization were heated for longer than 5 min. Thermoinactivation kinetics of IgE revealed an unexpected increase in the apparent quantity and biological activity of IgE heated for 5 min at 56 degrees. This fact could be due to auto-anti-IgE antibodies linked to the unheated IgE and which interfere with the biological activities of IgE and their quantification.

Basophils↗
PubMed1985

[Paracentric inversions in man. Apropos of 2 familial observations].

Two observations of paracentric inversion in man are reported. One is located on the long arm of chromosome 1 and was observed over two generations. The other is on the long arm of chromosome 5 and was transmitted over three generations. The possible implications of paracentric inversions on the phenotype and fertility are discussed.

Chromosome Banding↗
PubMed1985

[Paracentric inversion: a study of 2 new cases].

Two new cases of paracentric inversion are reported. One involved the short arm of chromosome 1 and affected two generations and the other involved the long arm of chromosome 5 and was described in 5 generations. The relationships between paracentric inversions and reproductive problems are discussed in the light of the literature.

Abortion, Habitual↗
PubMedDate not supplied

In vitro histamine release from human basophils triggered by a purified allergen from Dermatophagoides farinae: bimodal aspect of the dose response curve.

Histamine release experiments were performed over a 10(6)-fold range of allergen concentrations on basophils of patients sensitive to Dermatophagoides farinae. Two extracts of D. farinae were used, a partially purified one (Df 80d) containing several allergens and a highly purified component (Ag11). This histamine release patterns obtained with the complex allergen mixture Df 80d gave broad histamine release curves presenting an initial increase, followed by a decrease or a plateau, with occasionally a small dip. The Ag11-induced histamine release curves presented two peaks (bimodal pattern), separated by a more or less pronounced inhibition dip. No non-specific histamine releasing activity was observed with the basophils of two controls. The possible theoretical models for the bimodal histamine release patterns are discussed.

Allergens↗