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Biomedical subjects

B David

Publications and source records attributed to B David.

188 records · Page 11Linked to original sources
PubMedDate not supplied

Comparison of the allergenic potency of spores and mycelium of Cladosporium.

The allergenic potency of spore and mycelium extracts of Cladosporium was estimated by RAST, RAST inhibition and PCA tests. Spores contained a concentration of allergens higher than mycelia. Results of PCA tests suggested that spores contained specific allergens. However, in a comparative study of extracts from different species of Cladosporium animal and human models gave different estimates of the allergenic potency of the different species. In spite of these variations it was shown that extracts from spores of Cladosporium contained the highest amount of Cladosporium allergens.

Animals↗
PubMedDate not supplied

Nonspecific B and T cell-stimulatory activity mediated by mast cells is associated with exosomes.

Bone marrow-derived mouse mast cells (BMMC) and mast cell lines P815 and MC9 have recently been shown to induce antigen-independent B and T lymphocyte activation. It has been demonstrated that a physical contact between mast cells and B and T lymphocytes is not necessary since mast cell supernatants contain full activity. Electron microscopy studies revealed the presence in mast cell supernatants of small vesicles called exosomes with a heterogeneous size from 60 to 100 nm of diameter. When cocultured with spleen cells, purified exosomes induce B and T cell blast formation, proliferation as well as IL-2 and IFN-gamma production. In contrast to P815 and MC9 mast cell lines, a pretreatment with IL-4 is required for BMMC to produce active exosomes. Structurally, these exosomes were found to harbor immunologically relevant molecules such as MHC class II, CD86, LFA-1 and ICAM-1. Here we provide for the first time the evidence that mast cells use exosomes as sophisticated messengers to communicate with cells of the immune system.

Animals↗
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↗
PubMedDate not supplied

[Comparative study of 2 serological methods of diagnosis of acute respiratory Mycoplasma pneumoniae infections].

Complement fixation (CF) and haemagglutination (HAP) with M. pneumoniae antigen have proved valuable methods for the etiological diagnosis of acute respiratory infections. Both methods are sensitive and specific, provided purified antigens are used, of the Kenny and Grayston lipid antigen type for CF and the antigen treated by ultrasound and purified by centrifugation for HAP. Concomitant and repeated use of both tests is recommended, following the taking of paired serum samples at 7 to 10 day intervals the first samples being taken within the first ten days of the disease. A single test can only be used for a presumptive serologic diagnosis of acute infection with M. pneumoniae and only if the minimal diagnostic titre is taken into consideration, i.e. 1/64 for CF and 1/160 for HAP.

Acute Disease↗
PubMedDate not supplied

[Enzyme-immunoassay of grass-pollen and mites antibodies in rabbit antisera on magnetic polyacrylamide agarose beads (author's transl)].

Complex antigens were coupled to polyacrylamide agarose beads which had been made magnetic with iron oxide. Those beads were then used in an enzyme-immunoassay for quantitation of specific antibodies to grass-pollen and mites in rabbit antisera. The results obtained by a direct or an inhibition technique proved the specificity of this assay towards homologous antigens. Moreover, cross-reactions between the various species of grass-pollen could be shown. One advantage of this simple method is that it may avoid use of radioactive compounds.

Animals↗
PubMedDate not supplied

[Allergenic activity of mites in house dust].

The predominant role of mites in house dust respiratory allergy is now well established. Our laboratory has spent an important part of its time and activity studying the antigens present in D. farinae mites extracts and characterising the specific allergens responsible of respiratory allergy to D. farinae. Physicochemical and immunochemical studies let us to define major allergens in different biochemical fractions obtained from D. farinae extracts used for diagnostic and therapeutic purposes. Amongst the D. farinae specific antigens defined, one (Ag 11) is a specific major allergen and it has been isolated and chemically analysed. It is polypeptide of molecular weight of 28,000 d with p I not equal to 7 containing 5% of cysteine residues. The good stability and resistance to denaturation are in favour of numerous disulfide bonds.

Allergens↗