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F Leynadier

Publications and source records attributed to F Leynadier.

At least 73 records · Page 4Linked to original sources
PubMed1995

Flow cytometric monitoring of allergen induced basophil activation.

Human basophils express many clustered differentiation antigens (CD), including CD45; however, none are specific for these cells. In a previous study, we described a two-color immunofluorescence procedure, employing antibodies to CD45 and IgE for the cytometric evaluation of basophils. In the present work, we show that when sensitized basophils are stimulated by allergenic preparations, they demonstrate an upregulation of CD45 as well as a decrease in anti-IgE binding. Since CD45 antigen modulation was observed with all aeroallergens tested and the decrease in IgE expression varied with allergenic preparations, the measurement of CD45 upregulation was used to evaluate basophil activation. Using this approach, reproducible results were observed when atopic patients were tested at different time intervals. In addition, we show that the upregulation of CD45 on allergen stimulated basophils is a very rapid phenomenon that is observed after a few minutes and that this rapid flow cytometric method can also be used for investigations on nonallergenic mediators of basophil stimulation such as calcium ionophores.

Adult↗
PubMed1995

[Cutaneous reactions to heparin: immunological and clinical aspects].

Skin reactions to heparin are rare, the most frequent manifestation being skin necrosis. Reactions occur either as an isolated manifestation or within a context of heparin-induced thrombopenia. Urticarious and eczematous reaction, either localized at injection sites or with a general distribution, have been recently reported. In all cases, it is mandatory to withdraw heparin therapy. Such accidents can be observed with all types of heparin (standard heparin and low-molecular weight heparin). Cross-reactions between two types of heparin are frequent. Skin tests can be used to guide heparintherapy.

Drug Eruptions↗
PubMed1995

Systemic reactions to the Samsum ant: an IgE-mediated hypersensitivity.

BACKGROUND: In the United Arab Emirates the sting of the Pachycondyla sennaarensis ant (PSA) causes allergic reactions in certain persons. It is a common problem and is becoming a public health hazard. Up to now the diagnosis has been based only on the history, because the mechanism of the reaction was not yet established. OBJECTIVE: The aim of our study was to prepare an allergenic extract that would be used for skin tests and to prepare a reagent for specific IgE titration. Results of both skin tests and specific IgE were to be compared with the clinical history. METHODS: We studied 31 patients with anaphylactic reactions and performed clinical examinations, skin tests, and specific IgE antibody titrations. A control group of 22 subjects were also studied. RESULTS: In 30 of 31 patients (97%) findings of PSA skin tests and/or specific IgE were positive. In the control groups PSA skin test results were negative in 86% and negative for specific IgE in 68%. CONCLUSION: The study shows that the mechanism of the reaction to the sting of the PSA is a type I IgE-mediated hypersensitivity and that the diagnosis can now be confirmed by skin tests and specific IgE determination.

Adolescent↗
PubMed1995

Hypersensitivity to azathioprine mimicking gastroenteritis. Absence of recurrence with 6-mercaptopurine.

Hypersensitivity mimicking gastroenteritis is a rare complication of azathioprine therapy for which the mechanism is unknown. We report a case of devastating diarrhoea and vomiting due to azathioprine treatment in which hypersensitivity to the imidazole moiety of azathioprine was demonstrated. This has important therapeutic implications: in this situation, 6-mercaptopurine, which is the portion of azathioprine responsible for the cytotoxic therapeutic effect, can be administered without recurrence of side-effects.

Adult↗
PubMed1995

[Practical aspects of leukotriene E4 determination in urine].

Leukotrienes constitute a class of potent biological mediators of inflammation and anaphylaxis. However, their routine assay in various biological fluids is restricted by the complexity of the methodology. Previously this could only be performed by research laboratories with high pressure liquid chromatography and radioimmunological capabilities. The recent availability of kits for immunoenzymatic assay of leukotrienes offers a new tool for clinical laboratories provided the limitations of the method are understood. We suggest a simplified methodology for direct urinary LTE4 detection and outline a number of areas of concern encountered with this method.

Adult↗
PubMed1994

[Cold urticaria].

Explore the source record for details and available documents.

Cold Temperature↗
PubMed1994

[Why are some allergens enzymes?].

In the last ten years, progress in the field of allergy research has led to the purification of some of the major allergens and to a better knowledge of their physico-chemical properties. A number of studies have shown that some allergens have enzymatic activities. Molecular biology has provided the means to clone and sequence genes encoding these allergens and to produce recombinant allergens in yeast and bacteria. Epitope mapping of natural and synthetic allergens, using polyclonal or monoclonal antibodies and cell-stimulation tests, has also contributed greatly to the understanding of their immunogenicity and allergenicity. Analysis of these new data allow us to explain why some allergens are enzymes.

Acari↗
PubMed1994

Effects of acrivastine and terfenadine on skin reactivity to histamine.

The response to the histamine hydrochloride prick skin test was studied in 24 healthy volunteers who received, in random order and at least four days apart, acrivastine (8 mg), terfenadine (120 mg), and placebo. The tests were performed on either side of the back before and at the time of administration (single dose), then every 30 minutes for two hours, and every hour for the following four hours. Evaluation was based on the mean of two measurements of the surface area of the wheal-and-flare reaction accompanied by assessment of topical pruritus. The response to histamine was decreased markedly in the two active treatment groups. Although within one hour of injection, the activity of both antihistamines was consistently greater than that of placebo, the kinetics of action of the two products nevertheless differed; indeed acrivastine was active against flare and wheal earlier (within 30 minutes); terfenadine proved to be more active than acrivastine only on flare and only at the later times (four, five, and six hours). The safety study primarily demonstrated drowsiness in one-fourth of the patients receiving placebo and active treatment.

Drug Hypersensitivity↗
PubMed1993

[Intolerance to sulfonamides in HIV infected subjects. Toxic and allergic origin].

Intolerance to sulfonamides is very frequent in HIV-infected subjects and 10 times more common than in the general population. There are 2 types of intolerance to sulfonamides: early reactions with urticaria or angioedema, which are IgE-dependent, and late reactions with febrile rash, which occur between the 6th and 12th days of treatment and represent the vast majority of allergic manifestations in HIV-infected subjects. Clinically, these reactions resemble serum sickness, but all physiopathological hypotheses point to toxic process. The degradation of sulfonamides has two different pathways: the N-acetylation pathway which is genetically determined and saturable, and the cytochrome P450 pathway which produces toxic hydroxylamine metabolites "detoxified" by glutathione. In HIV-infected subjects detoxication is thought to be incomplete due to an acquired deficiency of glutathione and probably increased in the presence of a slow acetylation profile.

AIDS-Related Opportunistic Infections↗
PubMed1993

Purification of human IgG4 subclass with allergen-specific blocking activity.

Blocking antibodies (bAb) induced by allergen immunotherapy are restricted to the IgG1 and IgG4 subclasses, with IgG1 predominating early and IgG4 coming later. Study of IgG4 bAb has been limited, in part, by the absence of a method to purify IgG4. We describe a rapid immunoaffinity chromatographic method for the purification of that subclass from whole serum. Starting serum (TR) contained 90 micrograms/ml Dactylis glomerata (orchard grass) pollen (DGP)-specific IgG4, measured by indirect ELISA. The blocking activity of TR was assayed in vitro on IgE-sensitized human basophils. Immunoadsorption on a strong-binding anti-IgG4 monoclonal antibody (mAb) removed about 90% of the total and allergen-specific IgG4 and nearly all of the blocking activity from TR. An IgG4-rich fraction was then obtained by absorption of several small volumes of TR on a weak-binding anti-IgG4 mAb column at neutral pH followed by elution with glycine-HCl buffer. The pooled eluates contained 82% IgG4, amounting to a 65-fold purification of the serum IgG4; the yield was approximately 30%. Nearly all the DGP-specific antibody was in the IgG4 component of the eluate. The blocking activity of the eluate was approximately equal to that of TR. Immunoblot patterns with the eluate and with TR on SDS-PAGE of DGP were nearly identical. This method thus provides a fully active, relatively pure IgG4 blocking antibody. Moreover, the results reinforce the importance of using a well-chosen mAb when purifying proteins by immunoaffinity chromatography.

Adult↗