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P W Heymann

Publications and source records attributed to P W Heymann.

36 records · Page 2Linked to original sources
PubMed1991

Airborne dust mite allergens: comparison of group II allergens with group I mite allergen and cat-allergen Fel d I.

The form in which allergens become airborne is important because it may influence both symptoms caused by allergen exposure and methods used to reduce exposure. The group I allergens from dust mites only become airborne during disturbance and fall rapidly, which is in keeping with their being carried on fecal pellets. Their mean size is approximately 20 microns in diameter. By contrast, the cat-allergen Fel d I is airborne on particles varying from greater than 10 to less than 2 microns in diameter, some of which remain airborne even without disturbance. A second group of mite allergens, molecular weight 14,000, are equally important and are associated predominantly with mite bodies. With a monoclonal antibody-based assay and a cascade impactor, we have investigated the form in which group II mite allergens become airborne. The results reveal that these allergens only become airborne during disturbance and that they fall within 15 minutes. However, the mean size of particles carrying group II allergens appears to be slightly smaller than the mean size of particles carrying group I allergens. In addition, the quantities of group II allergen becoming airborne during disturbance (mean, 26 ng/m3) could not be explained by the quantity found in fecal particles. Thus, group II mite allergens become airborne in a form quite distinct from cat allergens and very similar to group I mite allergens; however, it appears unlikely that fecal particles are the main form in which group II allergens become airborne.

Allergens↗
PubMed1991

Epidemiology of the relationship between exposure to indoor allergens and asthma.

A very high prevalence of immediate hypersensitivity to common indoor allergens can be demonstrated among children and young adults, with asthma. Recent progress in the immunochemistry of cat, dust mite and cockroach allergens has made it possible to measure exposure to these allergens and to start to define threshold levels of exposure which increase the risk of sensitization and symptomatic asthma. Indeed, it is already clear that exposure to greater than 2 micrograms group I dust mite allergen (or 100 mites) per gram of dust increases the risk of children developing sensitization and asthma. Furthermore, from studies on patients presenting to emergency rooms with asthma, it is clear that the risk of sensitization to allergens derived from cats or cockroaches or grass pollen is restricted to patients who are exposed to high levels of these allergens. Given the increasing morbidity and mortality of asthma it is clear that therapeutic efforts should be focused on identifying relevant allergens and advising patients about techniques for reducing exposure.

Air Pollution, Indoor↗
PubMed1990

Conformational stability of B cell epitopes on group I and group II Dermatophagoides spp. allergens. Effect of thermal and chemical denaturation on the binding of murine IgG and human IgE antibodies.

The conformational stability of B cell epitopes on the 25-kDa group I and 14-kDa group II mite allergens was compared by using heat-treated or chemically denatured allergens to inhibit the binding of native 125I allergens to murine mAb or to human IgE antibodies. Structural changes after treatment were assessed by SDS-PAGE and circular dichroism spectroscopy. Heating for 1 h at greater than 75 degrees C, treatment at pH 2.0 or pH 12.0, or with 6M guanidine or 6M urea, reduced the binding of the group I allergens to mAb or IgE antibodies by 10- to 1000-fold. The group II allergens were heat stable and even after prolonged heat treatment (5 h at 75 degrees C or 30 min at 100 degrees C) their antibody binding activity was reduced by less than twofold. The group II allergens were also resistant to pH and to denaturation with 6M guanidine. However, after reduction and alkylation, antibody binding sites on both the group I and group II allergens were destroyed. Reduction of disulfide bonds with 2-ME caused a marked shift in the molecular mass of group I allergens on SDS-PAGE, from 25 kDa to 28-31 kDa. Reduction and alkylation also generated two high m.w. forms of Der p I and Der f I. After heating (100 degrees for 30 min), both Der f I and Der f II retained significant secondary structure, as judged by circular dichroism spectroscopy, but on reduction they showed the typical spectra of fully denatured proteins (greater than 85% random structure). The results show clear differences between the susceptibility of B cell epitopes on the group I and group II allergens to denaturation. Despite these differences in stability, both allergens are equally potent immunogens for IgE antibody responses in man. The results support the view that the physical properties of allergens (low m.w. and solubility), limiting low dose exposure (1 to 10 ng/day), and host genetic and immunoregulatory processes, are more important than gross structural features in the induction and maintenance of IgE antibody responses.

Alkylation↗
PubMed1990

Recent progress in mite allergen immunochemistry.

The successful purification of several mite allergens within the last few years has considerably enhanced our understanding of mite allergen immunochemistry. The role of these glycoproteins in stimulating human IgE ab and their role as immunogens in mice and rabbits has been studied extensively in a number of laboratories worldwide. In particular, purified allergens have facilitated the production of murine IgG Mabs that have been used to purify mite allergens by affinity chromatography; to investigate the diversity of antigenic sites on purified allergens; and to develop Mab based immunoassays for measuring allergen concentrations in dust samples and extracts. Full amino acid sequencing of several mite allergens is now in progress together with efforts to identify antigenically important peptide fragments. Such investigations are aimed to further increase our knowledge of humoral and cellular immune responses at the molecular level. For years, pollen counts have been used to judge airborne pollen allergen levels and to predict, in turn, the severity of symptom days for patients with hay fever. In contrast, simple methods for measuring dust allergens (e.g., mite allergen) have not been available. The development of Mab immunoassays, which can be converted from radiolabeled to enzyme labeled or fluorescence labeled assays, should provide rapid and quantitative measurements of specific mite allergen levels in house dust. Not only can such measurements provide useful clinical information in judging the exposure of patients to mite allergen, but the effectiveness of allergen avoidance regimes can be monitored objectively. By measuring the concentration of specific allergens in extracts, these assays could significantly improve efforts to standardize extracts used for diagnosis and treatment.

Allergens↗
PubMed1989

Antigenic and structural analysis of group II allergens (Der f II and Der p II) from house dust mites (Dermatophagoides spp).

Monoclonal antibody affinity chromatography was used to purify two homologous mite allergens, Der f II from Dermatophagoides farinae and Der p II from D. pteronyssinus. They have the same molecular weight (MW) (15 kd) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, they have similar amino acid compositions, and their N-terminal amino acid sequences differ in only four of the first 35 residues. An excellent correlation was observed between IgE antibody to Der f II and Der p II measured in sera from 65 mite-allergic patients (r = 0.94; p less than 0.001) and between quantitative intradermal skin tests to both allergens. A third allergen (Der f III, MW 29 kd) was purified from D. farinae by repeated gel filtration. In sera from 51 mite-allergic patients, IgE antibody to Der f II, Der f III, and previously purified Der f I (MW 24 kd) was detected in 92%, 16%, and 78% of the sera by radioimmunoassay, respectively. Most patients, 41/51 (80%), demonstrated IgE antibody to more than one allergen. With monoclonal antibodies fully cross-reactive with Der f II and Der p II, a two-site immunoassay was developed for measuring absolute quantities (nanograms or micrograms) of these allergens. In extracts rich in mite-fecal material (n = 5), Der f I and Der p I (group I allergens) and Der f II and Der p II (group II allergens) were measured in ratios of 11:1 to 35:1. Lower ratios (1.1:1 to 7:1) were observed in mite body extracts (n = 6). These experiments clearly define a second group of major dust mite allergens that demonstrate extensive structural and antigenic homology.

Allergens↗
PubMed1987

Epitope mapping of two major inhalant allergens, Der p I and Der f I, from mites of the genus Dermatophagoides.

The repertoire of antigenic sites on two major dust mite allergens, Der p I of Dermatophagoides pteronyssinus and Der f I of D. farinae, was studied using murine (BALB/c) monoclonal antibodies (Mab), polyclonal rabbit IgG antibodies, and human IgE antibodies. Fifty-three IgG Mab were analyzed from six different fusions (five vs Der p I, one vs Der f I). By antigen binding radioimmunoassay (RIA), most Mab were either Der p I or Der f I specific, and only 2/53 bound to both allergens. Epitope mapping studies using cold Mab to inhibit the binding of six 125I labeled Mab to solid phase allergen defined four nonrepeated, nonoverlapping epitopes on Der p I, a single species-specific epitope on Der f I and a cross-reacting epitope present on each allergen. All but one of the 53 Mab bound to one of these six epitopes. Seventy percent (25/35) of anti-Der p I Mab were directed to the same epitope, suggesting that this epitope is immunodominant for BALB/c mice. Similarly, 88% (16/18) of anti-Der f I Mab bound to the same epitope on Der f I. Parallel cross-inhibition curves were obtained using the species-specific Mab, 10B9, and the cross-reacting Mab, 4C1, to compete for binding to Der p I, suggesting that the epitopes defined by these two Mab on Der p I are adjacent to one another. Both murine Mab and polyclonal rabbit IgG antibodies to cross-reacting sites on both allergens were used to inhibit binding of human IgE antibodies to Der p I by using 19 sera from mite allergic patients. Cross-reacting rabbit IgG antibodies strongly inhibited all sera tested (mean 79.5% +/- 7.7) and two Mab, 10B9 and 4C1, partially inhibited (38% +/- 12). However, the four Mab directed against separate species-specific epitopes (including murine immunodominant sites) showed little or no inhibition (less than or equal to 20%). Our results suggest that most of the epitopes defined by Mab are not the same as, or close to, those defined by human IgE antibody. The striking differences in the repertoires of murine IgG and human IgE antibody responses to Der p I and Der f I could be explained by genetic differences or by altered antigen processing and presentation occurring as a result of different modes of immunization in mice and in mite allergic humans.

Allergens↗
PubMed1987

Monoclonal immunoassays for major dust mite (Dermatophagoides) allergens, Der p I and Der f I, and quantitative analysis of the allergen content of mite and house dust extracts.

Monoclonal, two-site radioimmunoassays (RIAs) were developed to measure allergen Der p I of Dermatophagoides pteronyssinus or Der f I of D. farinae. Microtiter plates coated with monoclonal antibody (Mab) were incubated with mite extract, and bound allergen was detected with a second 125I-labeled Mab of different epitope specificity. The Mab RIAs were very sensitive (nanogram range) and highly specific. D. pteronyssinus extracts with different concentrations of Der p I demonstrated parallel binding curves, whereas a potent D. farinae extract demonstrated less than 5% of the Der p I binding in the same assay. Similar parallel curves were obtained with several D. farinae extracts in the Der f I assay, whereas D. pteronyssinus extract demonstrated little or no binding. The Mab RIAs were compared with an inhibition RIA that measured cross-reacting determinants on both Der p I and Der f I (antigen P1 equivalent [AgP1Eq]). The results demonstrated good quantitative agreement between these assays in commercial mite and house dust extracts (mean difference 1.57 +/- 0.5-fold). Thirty house dust samples with known mite counts, Der p I, and AgP1Eq content were also compared. The summed Mab RIA values for Der p I and Der f I demonstrated a very good correlation with AgP1Eq values (r = 0.86; p less than 0.001) and with assessments of total mite-allergen content by RAST inhibition (n = 21, r = 0.77; p less than 0.001). Furthermore, in samples with more than 10 mites per 100 mg of dust, the Der p I: Der f I ratio closely correlated with the ratio of the two mites counted by microscopy (n = 15, r = 0.89; p less than 0.001). The Mab RIAs can measure allergen levels in mite or dust extracts without the need for purified allergen or affinity-purified antibodies and can readily be standardized. These assays will be useful in epidemiologic studies of allergic asthma, to assess patients' exposure to mite allergens, and the effects of avoidance regimens. Because of the long-term stability and reproducibility of the reagents, Mab-based assays for specific allergens will also play an important role in the standardization of mite and other allergen extracts.

Allergens↗
PubMed1986

Antigen Der f I from the dust mite Dermatophagoides farinae: structural comparison with Der p I from Dermatophagoides pteronyssinus and epitope specificity of murine IgG and human IgE antibodies.

The physicochemical and antigenic properties of an allergen purified from Dermatophagoides farinae, Der f I, were compared with Der p I from Dermatophagoides pteronyssinus. On SDS-PAGE, Der f I migrated as a single polypeptide chain with the same m.w. as Der p I (24,000). Two isoallergenic peaks of Der f I were identified on preparative isoelectric focusing (pI 5.7 to 6.3 and pI 6.6 to 6.95). Fractions from each peak were shown to have an identical amino acid composition (which was similar but not identical to Der p I) and the same N-terminal amino acid sequence. There was a good correlation between quantitative intradermal skin tests to both purified allergens and to D. farinae extract in mite-allergic patients, with positive results when using as little as 10(-5) micrograms/ml of Der f I. The majority of sera with detectable IgE antibody to D. farinae also had IgE antibody to Der f I both among children (29/42 = 69%) and adults (55/63 = 87%). By RAST, there was an excellent correlation between IgE antibody to Der f I and Der p I in sera from 42 mite-allergic children (n = 0.94, p less than 0.001). Polyclonal IgG antibodies from six mice immunized with Der f I showed preferential binding to that allergen, and most monoclonal antibodies (16 of 18) raised against Der f I did not bind Der p I. However, two monoclonal antibodies from this fusion showed cross-reactive binding to both allergens. Immunoabsorption experiments, using D. pteronyssinus and D. farinae extracts coupled to Sepharose, showed that a large proportion of murine antibodies (74% to Der p I and 60 to 93% to Der f I) could not be absorbed by the heterologous extract on the immunosorbent. In contrast, in sera from seven mite-allergic patients, most of the specific IgE and IgG antibody (i.e., greater than or equal to 82%) was removed by either immunosorbent. Thus, Der f I and Der p I represent a homologous pair of major allergens which possess both cross-reacting and species-specific epitopes. The antibody response in mice immunized with either allergen in complete Freund's adjuvant was largely directed against species-specific epitopes, whereas in allergic humans, IgE- and IgG-specific antibodies bound predominately to cross-reacting epitopes.

Allergens↗
PubMed1986

Cross-reacting and species-specific determinants on a major allergen from Dermatophagoides pteronyssinus and D. farinae: development of a radioimmunoassay for antigen P1 equivalent in house dust and dust mite extracts.

Two species of mites of the genus Dermatophagoides are common in house dust and make a major contribution to the allergen content of house dust. As judged by skin tests and the radioallergosorbent test, these mites, D. pteronyssinus and D. farinae, demonstrate extensive cross-reactivity. When the major allergen from D. pteronyssinus, antigen P1, was compared with the equivalent allergen from D. farinae, these two proteins were found to have both species-specific and common antigenic determinants. With specifically purified antibodies directed against the common determinants, we developed a radioimmunoassay for these antigen P1 equivalent proteins in mite extracts as well as house dust extracts. The quantity of allergen in dust from 63 houses (255 samples) was measured, and values ranged from less than 100 to greater than 100,000 ng/gm of fine dust. The correlation between antigen P1 equivalent (ng/gm) and the number of mites per gram of dust (identified by microscopy) was very good (r = 0.74; p less than 0.001). Furthermore, this correlation was not affected by the species of mite in the dust sample. Of 9243 mites identified, 95% were of the genus Dermatophagoides, and of these, 16.4% and 18% could be positively identified as D. farinae and D. pteronyssinus, respectively. When the assay for antigen P1 equivalent was applied to isolated components of mite cultures of both species, significant allergen was found in the mite bodies, cuticles, and their excreta (fecal particles). For the house-dust samples, less than 10% of the allergen measured could be explained by the allergen content of mite bodies. Our results demonstrate that a radioimmunoassay for antigen P1 equivalent can provide an accurate and simple means of assessing the quantity of mite-derived allergen in dust-mite extracts, house-dust extracts, or house dust.

Allergens↗
PubMed1986

Airborne allergens associated with asthma: particle sizes carrying dust mite and rat allergens measured with a cascade impactor.

Patients with asthma may develop acute symptoms after exposure to domestic or laboratory animal allergens; however, they are usually not aware of a direct relationship between their acute attacks and exposure to pollen or dust mite allergens. The present experiments were designed to study whether the differences in symptoms could be explained by differences in the number or size of particles carrying airborne allergens. Airborne particles were collected with a filter or on the stages of a cascade impactor, and allergens were measured by use of inhibition radioimmunoassays. In rat rooms and during disturbance of rat litter, a large proportion of rat urinary allergen (45.9%) was collected on the second stage of the impactor (mean size approximately 7 microns diameter). When sampled 15 to 35 minutes after disturbance, 16% of these medium-sized particles were still airborne. By contrast, during disturbance of house dust, a significantly larger proportion of dust mite, antigen P1 (80.6 +/- 11.8%; p less than 0.001) was collected on the first stage of the impactor, and in keeping with the apparent size of these particles (diameter greater than 10 microns), very little of this allergen (less than 4%) was still airborne when sampled 15 to 35 minutes after disturbance. With nebulized diluted rat urine, approximately 75% of the allergen was collected on the fourth and final stages of the cascade impactor in keeping with the expected size, 0.5 to 3 microns in diameter. These results demonstrate that natural exposure to both allergens is strikingly different from the conditions used for bronchial provocation.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerosols↗
PubMed1985

Medical examination of children referred for special education.

The results of medical examinations of 184 children referred for special educational services were reviewed, with particular attention paid to the value of the examination in the detection of abnormalities that would have an adverse educational impact and of previously undiagnosed abnormalities. Seventeen students (9%) were found to have educationally important abnormalities previously unknown to the school. Fifteen students had abnormalities detected through screening tests. The two remaining students had abnormalities apparent on physical examination that conceivably could interfere with physical education but should not hinder academic achievement. Thus, a separate physical examination, apart from those recommended for all children by the American Academy of Pediatrics, may not be productive for children referred for special educational services, but screening tests currently available in many schools are more likely to be beneficial.

Adolescent↗
PubMed1985

Natural exposure and serum antibodies to house dust mite of mite-allergic children with asthma in Atlanta.

Pyroglyphid mites in house dust are important allergens associated with asthma in Europe, but comparable studies of house dust mites in the homes of patients with asthma have not been done in the United States. We examined the distribution of mites and mite allergen in the houses of 20 mite-sensitive children with asthma in Atlanta and measured IgE antibodies to mite allergens in their sera. One or more dust samples from bedding, bedroom floor, television room floor, or television room furniture from 17/20 houses contained greater than 10,000 ng of antigen P1 equivalent per gram of fine dust; amounts ranged from 280 to 230,400 ng/gm. Allergen levels were higher in dust samples from furniture and bedding than from floors. Dust samples obtained from houses in June to September had more mites and mite allergen than those houses sampled in March to April; relative humidity in the room also was higher in June to September. Mite numbers and allergen in floor and furniture samples were correlated with relative humidity in the room and were high when relative humidity was greater than 50%; antigen P1 equivalent was greater than 10,000 ng/gm in 21/39 such samples. Dermatophagoides pteronyssinus was present in all houses and dominant in 11/20. D. farinae was found in 17 houses and was dominant in six. All children studied had high IgE antibody with either D. farinae or D. pteronyssinus RAST; 16 of the 20 children also had IgE to antigen P1. It is likely that the IgE antibody responses in these 20 children with asthma were a direct result of exposure to high levels of mite allergen.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

The relevance of inhalant and food allergens to the etiology and management of patients with atopic dermatitis.

Patients with atopic dermatitis have IgE antibodies to common environmental antigens, both foods and inhalants. Such antibodies are probably relevant and exposure to the corresponding antigens can give rise to eczema. Nevertheless, the mechanisms involved and the role of other etiologies, e.g. contact reactions, remain to be elucidated. Patients with atopic dermatitis should have comprehensive evaluations to determine the role of environmental antigens.

Air Pollutants↗
PubMedDate not supplied

Asthma and rhinitis related to laboratory rats: use of a purified rat urinary allergen to study exposure in laboratories and the human immune response.

Using the major rat allergen as a model has made it possible to study both natural exposure and the human immune response to an important laboratory animal. The close correlation between positive skin tests to whole rat urine and IgE antibody to the major urinary allergen in this and previous studies supports the use of this protein as a model rat allergen. Measurements of airborne rat allergen confirm that the maximum levels are higher than those reported with pollen or mite allergens. However, it is possible that exposure to rat allergens is comparable to levels of exposure to cat salivary allergens in houses with cats. The clear implication is that the high levels of exposure are responsible for the fact that a large proportion of exposed individuals develop IgG antibodies. Our results suggest that the prevalence of IgG antibodies (not individual levels) in a group of workers would be a good guide to exposure. This leaves unresolved why some of the individuals who develop IgG ab also develop IgE ab and become at risk for developing asthmatic responses. Only part of this risk is related to atopy. A striking feature of all the studies on animal allergy is the close association between IgE ab and asthma. It appears clear that it is those immune responses that include IgE ab that are a risk factor for asthma. It is not sensible for anyone to remain consistently sick with asthma and continue working with laboratory animals because there are well documented examples of occupational asthma that has not resolved after ceasing exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Allergens↗