[The need for and limits of diagnostic tests for professional asthma].
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Asthma↗
Biomedical subjects
J C Bessot
Publications and source records attributed to J C Bessot.
Urticaria and rhinitis to shrubs of Ficus benjamina and breadfruit in a banana-allergic road worker: evidence for a cross-sensitization between Moracea, banana and latex.
BACKGROUND: We report the case of a road worker with a food allergy to banana, who developed urticaria and rhinitis when cutting shrubs of Ficus benjamina and breadfruit. He did not develop an allergy to latex of Hevea brasiliensis. RESULTS: Sensitization to latex of F. benjamina, H. brasiliensis, breadfruit and banana was demonstrated using skin tests and specific IgE measurements. RAST inhibitions procedures showed that specific IgE to breadfruit latex cross-reacted more strongly with latex of H. brasiliensis and banana than with latex of F. benjamina with the same extract. CONCLUSION: Given the wide distribution of Moracea trees in tropical regions, sensitization to latex of H. brasiliensis and banana could be a consequence of sensitization to Moracea members; F. benjamina does not seem to be the only Moracea responsible for cross-allergy with latex and fruit. Consequently, it seems interesting to test other members of the Moracea family in patients sensitized to latex of H. brasiliensis and banana. Sensitization to breadfruit could be a risk factor for sensitization to latex of H. brasiliensis.
Adult↗
[Physiopathology of hay fever].
Pollinosis is a model physio-pathology for IgE-dependent diseases. Rhinitis and conjunctivitis are the parent symptoms, with asthma a non-exceptional complication. The mechanisms are linked to an immuno-allergic inflammation; the observed differences are due to specific anatomo-physiologies of the sensitive cells. The pollen allergens are collected by the CPA and expressed after cleavage into peptides, at the surface of the CPA in association with class II HLA molecules. T-lymphocytes recognise the complex HLA-peptide molecules. Type Th2 lymphocytes produce the cytokines that the necessary for the synthesis of IgE (IL4, IL13...). At the stage of silent clinical sensitivity the precocious and delayed effector stages of immediate hypersensitivity follow. The precocious stage corresponds with degranulation of cells that express Fc epsilon R1, for release of vaso-active and lipid mediators that produce the immediate symptoms of pollinosis. The delayed phase corresponds with a flood of eosinophils, which release their toxic proteins proteins and also take part in oedema and nasal obstruction. Mucosal innervation, neurotransmitters and neuromediators also intervene in the modulation of symptoms.
Allergens↗
[Mites and their allergens: identification and extermination methods].
Mite allergens are the main allergens in indoor environment. Using different means of assessing exposure to house dust mites (Acarex-test, major allergen (Der p 1 + Der f 1, Der p 2 + Der f 2), content measured by ELISA) has allowed better identification of mite reservoirs and allergens in patients' homes. House dust mite control measures are based on the knowledge of factors contributing to mite development, especially indoor relative humidity. Mite allergen avoidance strategies include 3 different methods: avoidance of mite producing allergens, elimination of mite reservoirs, especially textile reservoirs, dwellings designed so as to inhibit mite proliferation. Only controlled trials can estimate patients' compliance with proposed avoidance measures. Avoidance protocols should be adjusted to each individual by medical indoor environment counselors in order to optimize mite allergen reduction.
Allergens↗
[Respiratory allergies and household allergenic environment].
Based on immunoassay techniques used to identify and quantify major indoor allergens, epidemiological studies have demonstrated that level of exposure depends on the geographical situation (climate, urbanization) and that there is a relationship between exposure and sensitization of predisposed patients. Most of the major mite allergens are proteases. For mammals and cockroaches, the major allergens belong to the retinal protein binding group. Determination of the airborne characteristics of the major indoor allergens is helpful in better understanding the pathophysiology of asthma. In the future, more precise diagnosis and more efficient immunotherapy will be possible through the development of recombinant allergens. The efficacy of allergen avoidance in allergic asthma has been demonstrated in several studies. Thus the respective role of different household allergens should lead to improved diagnosis and treatment of allergic diseases.
Acari↗
Genetics and specific immune response in allergy to birch pollen and food: evidence of a strong, positive association between atopy and the HLA class II allele HLA-DR7.
BACKGROUND: In some geographic areas birch pollen represents the most prominent cause for airborne allergic diseases. Up to 70% of patients allergic to birch pollen are hypersensitive to fruits, especially apples. Associations have been found, in some instances, with a sensitivity to aeroallergens and HLA class II genes. OBJECTIVES: We investigated whether susceptibility or resistance to birch pollen allergy with and without food allergy was associated with HLA class II genes. METHODS: Blood samples were obtained from 2 groups of unrelated European-born white adults: 42 atopic patients (31 of them with asthma) and 42 healthy control subjects with no personal or familial history of asthma or atopy. Their antibody responses to birch pollen, apples, grass, and weed pollens were evaluated by skin tests, RASTs, and immunoprints. Genomic DNA was extracted from PBLs. The exons of DQA1, DQB1, DRB1, and DPB1 genes were selectively amplified by using the PCR method. Genotyping was carried out by digestion of the amplified DNA products with allele-specific endonucleases (PCR-RFLP), which recognize allelic variations in the polymorphic exon. RESULTS: We found no significant differences in the frequency of DPB1 alleles between patients and control subjects. HLA class II DR4 and/or DR7 alleles were present in 42.6% of the patients and in only 2.4% of the healthy subjects. These results confirm a previous study of a group of polysensitized atopic patients, which showed that DR4 and DR7 alleles were rare in healthy control subjects and frequently observed in atopic subjects with or without concomitant asthma. CONCLUSION: We conclude that the allele HLA-DR7 is significantly involved in the presentation of apple and pollen allergens. However, we suggest that this susceptibility is more related to atopy than to specific responses to allergens.
Adult↗
[Occupational asthma caused by a coloring reagent].
A case of occupational asthma associated with rhinitis and conjunctivitis occurred in a patient working in a textile factory and exposed to different coloring reagents is reported. Symptoms appeared in phases correlated with changes in the use of the coloring reagents. Prick tests were carried out with the different coloring reagents and were positive for the yellow color. The test was followed by a clear increase in bronchial hyperreactivity to methacholine. Some individual preventive measures, such as wearing a face mask, led to reduction then disappearence of the symptoms.
Adult↗
[Exploration of respiratory allergies and prevention].
Respiratory allergies are found in more than 50% of the asthmatics. Allergen sources and their secondary reservoirs are better known. The different methods of exploration of allergic asthma consist of clinical history, skin tests, and in vitro tests particularly measurement of specific serum IgE. Specific challenge tests are realized with nebulized allergenic extracts as well as in the realistic manner with substances in occupational environment. It is equally important to evaluate the allergenic environment, especially by simple but informative techniques such as the Acarex test for mites. The eviction methods are the same for primary prevention (to prevent sensitization) as well as for the secondary prevention (to reduce the disease exacerbation in the patients already sensitized). The eviction methods mainly concern the allergens of mites, domestic animals, cockroaches and the molds.
Allergens↗
[Occupational asthma].
Occupational asthma is specifically induced by repeated exposure to substances in the work place. Diagnosis requires using the results of numerous tests, and a challenge test is the most appropriate to establish the diagnosis of occupational asthma due to chemical agents. Agents responsible for occupational asthma may be of animal or vegetable origin, or may be chemical agents. The pathophysiological mechanisms of occupational asthma are not well known. It is probable that immunologic mechanisms play an important role, in particular in occupational asthma due to glycoproteins. An important feature of occupational asthma is the relationship to chemical substances, for which the mechanisms are often still hypothetical. From the legal viewpoint, a recent law holds the promise of better compensation for those who are afflicted.
Asthma↗
The role of mattress bases in the mite infestation of dwellings.
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Allergens↗
[Pollen environment and its evaluation].
We review the methods available for determining airborne pollen. In addition to the classical gravimetric and volumetric methods, new immunochemical techniques are also used for detecting allergenic pollen and measuring of the size of allergen-carrying particles. Pollen counts are available in France for 39 urban sites. In the last decade changes in the pollen environment have basically concerned higher counts from resinous trees in southern France and birch tree counts in northern France as well as a lesser role for ash trees. Among the recent acquisitions, it has been demonstrated that allergens are present in twigs and leaves, or even the bark of certain trees. Interactions with atmospheric pollution is better understood and could be a contributing factor to the increasing number of people allergic to pollen. Pollen allergens can be carried on particles of various sizes and immunochemical studies have demonstrated that gramineous pollen allergens can be carried on starch particles less than 3 mu in diameter. These recent studies would explain the apparent disagreement between pollen counts and the number of clinical manifestations.
Air Pollutants↗
Skin testing with recombinant allergens rBet v 1 and birch profilin, rBet v 2: diagnostic value for birch pollen and associated allergies.
OBJECTIVE: This study assesses the value of two recombinant birch allergens for diagnosis of patients sensitized to birch pollen with or without associated food allergy. METHODS: Fifty-one patients with positive skin test responses to Betulaceae and seven nonallergic control subjects were investigated; specific IgE antibodies were evaluated by specific immunoassay and blot immunodetection. RESULTS: Among 51 patients, 47 reacted to rBet v 1 and 10 to rBet v 2. Seven patients reacted to both recombinant allergens. In skin prick tests we found a correlation between the wheal produced by the commercial birch extract and the wheal produced by rBet v 1. Among 47 patients with positive test responses to rBet v 1, 83% had IgE binding to the Bet v 1 protein as determined by immunoblotting. Among 10 patients sensitized to rBet v 2, six had IgE binding to Bet v 2. Eleven patients with negative results, as determined by immunoblotting, had low levels of birch IgE in the sera (less than 10 kU/L) and low concentrations of IgE to rBet v 1 or rBet v 2 in ELISA. The nonallergic control subjects (n = 7) did not react to rBet v 1 or rBet v 2 in skin prick tests, nor did they have detectable amounts of specific IgE to rBet v 1 or rBet v 2. Histamine release tests confirmed sensitization to Bet v 1 in two patients with discordant results; for Bet v 2, one patient had positive results only at a high concentration, and one had results that remained negative. Thirty-four patients had birch pollinosis, and all reacted to rBet v 1. Patients who were monosensitized to birch never reacted to rBet v 2. Sensitization to rBet v 2 was only found in patients who reacted to other pollens (mainly grass). Twenty-nine patients demonstrated allergy to apples, cherries, or hazelnuts; and all reacted to rBet v 1. Among 11 patients with allergy to Umbelliferae, only three reacted to rBet v 2. CONCLUSIONS: Use of the two recombinant allergens (rBet v 1 and rBet v 2) always permits the diagnosis of birch sensitization. Sensitization to rBet v 1 is specific for birch and Rosaceae allergies, whereas sensitization to birch profilin, Bet v 2, is encountered in multisensitized subjects and is not always related to Umbelliferae allergy.
Adult↗
[New aero-allergens].
As the number of proteins recognized as causing allergic respiratory diseases increases, new aero allergens have appeared in the animal and vegetable realms, both in home and professional environments. Lepidoglyphus destructor and Blomia tropicalis, two mites found in storage areas, are particularly important in agricultural areas and in homes. Over the last ten years, the frequency of reactions to cockroaches has also increased in several countries. The allergenicity of non-biting insects is a frequent cause of allergy in certain countries including Japan. Chironomides cause respiratory diseases in professional and outdoor environments. The important role of Alternaria, a mold, in producing severe asthma has also been demonstrated. The pathophysiology of pollen-induced asthma has been shown to result from pollen allergens carried by particles less than 5 microns in diameter. Cyprus and ash tree pollen also cause an increasing number of pollinoses and flowers can cause rhinitis and asthma. Respiratory allergy to Ficus benjamina inaugurated a new type of allergies caused airborne allergens from non-pollinating plants. Allergy to latex raises a particular problem for health care workers. The immunochemical structures of the major and minor airborne allergens are now better known and the homologous structures of different allergens largely explains certain cross-reactions. In the future, recombinant allergens will probably be used to better understand the role of allergens in inducing and maintaining the allergic reaction and should help in our approach to diagnosis and therapy.
Acari↗
[Occupational asthma in an agricultural setting].
The prevalence of asthma in a farming environment is significant (from 3-7.7% according to various studies). The clinical picture has not been specified. The responsible agents are multiple and polysensitization frequent. Numerous substances of vegetable origin may be a cause, pollens, moulds, cereals, oil and protein producing plants, fibrous textiles, diverse plants and wood, etc. Amongst substances of animal origin the most frequent allergens incriminated are: allergens from mammals (horses, cattle, pigs), allergens from chickens and birds, arthropod allergens, insect allergens. Amongst chemical products those which are at risk to the respiratory system include insecticides, herbicides, fungicides, antibiotics and antiparasites. The diagnosis of the occupational character of asthma is sometimes difficult because of other causes of lung diseases in farm workers. The aetiological diagnosis is achieved by the clinical history, cutaneous tests, a level of specific serum IgE, and bronchial provocation tests which contrary to asthma in the industrial environment are not fundamental to the diagnosis except where chemical products are suspected. The mechanisms are sometimes intricate (IgE dependant mechanisms, non-specific liberation of histamine, activation of complement, intervention of endotoxins and pharmacological mechanisms...). Prevention may be carried out on behalf of the victim (for example wearing filtration masks in dusty work) and also carry out various methods to reduce the level of exposure to the allergen.
Agriculture↗
[Asthma, rhinitis and urticaria following occupational exposure to cyanoacrylate glues].
Cyanoacrylate glues are more and widely used in the industry because of easy handling and great sticking power. These very volatile and chemically reactive glues may not only cause contact eczema, but also rhinitis and asthma. Nineteen cases of asthma have been reported to date. We report two new cases of occupational asthma as well as one case of urticaria, a clinical symptom not yet described, to our knowledge. In the three cases, diagnosis was made based on a compatible medical history and positive realistic exposure tests. The mechanism is still unknown, due to the physical properties of cyanoacrylate glues; in fact, it is not possible to perform prick tests or specific IgE measurements. Besides the usual preventive measures, maintaining a relative humidity greater than 55% seems to induce polymerization of free monomers of alkyl cyanoacrylate, thereby reducing their volatility. Rhinitis and asthma due to cyanoacrylate glue may receive compensation as occupational diseases in France.
Adhesives↗
First report of anaphylactic reaction after fig (Ficus carica) ingestion.
We report an anaphylactic reaction which occurred very shortly after ingestion of a fresh fig. The IgE-dependent mechanism was demonstrated on the basis of positivity of the prick test performed with fresh fig (Ficus carica) extract. In addition, we were able to detect specific IgE to the same extract in the serum. The patient did not demonstrate sensitization to other common allergens involved in respiratory and food allergies. However, detection of specific IgE to F. benjamina indicated a sensitization to weeping fig. The CAP F. benjamina was partially inhibited by preincubation of the serum with fig extract, suggesting that these two species of Ficus share some common allergens. In this context, the assumption can be made that weeping fig was responsible for the initial sensitization in this patient.
Aged↗
[Importance of measuring exposure to the principal indoor allergens in allergic asthma].
Domestic allergens, such as mite and cat allergens, are a leading cause of allergic asthma. Allergen exposure is a risk factor for sensitization. Allergens also play a major role in the development of inflammation and non specific bronchial hyperreactivity as well as in the apparition and modulation of symptomatic asthma. The development of new means of detecting allergens (i.e. immunochemical assays including monoclonal antibodies, quantitative and semiquantitative guanine measurements for mite allergens) has made possible to identify allergens sources and reservoirs. The form in which domestic allergens become airborne is important. The group I and II allergens from mites, the major cockroach allergens are carried on large particles (mean size > 10 microns diameter); in contrast, the major cat allergens are airborne on small particles (40% < 5 microns). Guanine, a metabolic excretion product of mites, is used as a marker for mite feces and is correlated with the presence of major allergens from mites. A colorimetric method (Acarex-TestR) provides a simple and inexpensive method of assaying indoor mite allergen exposure for both doctor and patient alike. By using Acarex-TestR it is possible to evaluate the mite allergen exposure for a population in a particular country. The detection of allergens sources and reservoirs, the quantification of domestic allergens has enabled the evaluation of the effect of a reduction in allergen exposure to be better assessed. Recognition of the risks, environmental control and reduction in allergen loads, should be among the objectives of asthma management.
Air Pollution, Indoor↗