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M D Chapman

Publications and source records attributed to M D Chapman.

At least 145 records · Page 8Linked to original sources
PubMed1988

Epidemiology of emergency room asthma in northern California: association with IgE antibody to ryegrass pollen.

To examine the relationship between allergy and acute attacks of asthma, we have examined adult patients with acute asthma presenting during a defined pollen season. Sera from 59 patients presenting with acute asthma to the David Grant Medical Center emergency room at Travis Air Force Base during the spring "epidemic" of asthma were assayed for IgE antibody (Ab) to five allergens (mite, cat, cockroach, ryegrass pollen, and ragweed) with RAST. Control sera were obtained from 34 patients without asthma and 25 employees. The results demonstrate that 92% of the patients with asthma had greater than 200 units of IgE Ab to ryegrass pollen (approximately 20 ng of IgE Ab per milliliter) compared to 14% of the control subjects (chi 2 = 69; p less than 0.0001; odds ratio = 69). Some of the grass pollen--allergic patients also had increased levels of IgE Ab to ragweed, but only 25% had greater than 200 units. In contrast, there was no significant difference between subjects with asthma and control subjects in the prevalence of IgE Ab to the three indoor allergens (mite, cockroach, and cat). Twelve percent of the patients with asthma compared to 5% of the control subjects had greater than 200 units of IgE Ab to one of these three (chi 2 = 0.98; p greater than 0.1; odds ratio = 2.5).(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Anti-Idiotypic↗
PubMed1988

Hidden allergic factors in the etiology of asthma.

Increasing evidence from case control surveys, population studies and allergen avoidance studies suggest inhalant allergy plays an important role in the etiology of asthma. Recent studies in hospital emergency rooms have compared the prevalence of serum IgE antibodies to common allergens (mite, cat, cockroach, rye grass and ragweed pollen) in patients admitted with acute asthma attacks and in unselected age-matched control subjects. These studies, carried out in central Virginia and northern California, showed a highly increased prevalence of IgE antibodies to inhaled allergens among asthmatic patients, and suggest that the development of allergen specific IgE antibody responses is a major risk factor for emergency room admission with asthma. Presentation at the emergency room appeared to be related to patients' exposure to specific allergens: in central Virginia, in the fall, dust mite was the predominant allergy, whereas in northern California, in May-June, most asthmatic patients (greater than 90 percent) were allergic to rye grass. New immunoassay technology, based on the use of monoclonl antibodies, has been developed to measure the quantities of "indoor" allergens (mite, cat, cockroach) in asthmatic patients' houses. It is now possible to propose tentative levels of mite allergens which should be considered both as a risk for IgE antibody sensitization (2micrograms allergen/g dust) and as a risk for acute asthma attacks (10micrograms allergen/g dust). Future management of asthma will require analysis of indoor allergens and the development of efficient allergen avoidance procedures. Further research is necessary to investigate the relationship between airborne allergen levels, particle size and the precipitation of asthma attacks and also to investigate immunologic mechanisms which may cause bronchial hyperreactivity.

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↗
PubMed1987

Seasonal variation in dust mite and grass-pollen allergens in dust from the houses of patients with asthma.

In order to study seasonal variation in dust-mite allergen, we obtained dust samples from bedding, carpet, and/or sofas in 12 houses in central Virginia, monthly, for 1 year. The houses included those of nine patients with asthma of whom six were allergic to dust mites. Dust samples were assayed with an inhibition radioimmunoassay for mite allergen that detects cross-reacting determinants on Der f and Der p I from Dermatophagoides farinae and D. pteronyssinus, respectively. The results are expressed as micrograms of antigen P1 equivalent (AgP1Eq). The results demonstrate that large seasonal variations in allergen, i.e., more than twentyfold, can occur in dust from all sites and are not restricted to the houses of allergic patients. However, dust from some sites, particularly sofas, remained "high" (greater than 10 micrograms AgP1Eq per gram), whereas dust from other sites remained "low" (less than 1 microgram AgP1Eq per gram) throughout the year. Levels of mite allergen generally started to rise in July about 1 month after the rise in humidity. In August to December, the mean levels of AgP1Eq in house dust were highly significantly increased relative to April to May. In keeping with this finding, in 31 of 37 sites, the highest level for the year was observed in August through December. In four sites, mite bodies were counted, and the numbers increased sharply in June to July; however, they decreased in September in parallel with falls in humidity but several months before the fall in mite allergen. Ryegrass-pollen allergen in 12 sites was also assayed in house dust, and pollen-allergen levels demonstrated a sharp increase in May or June that fell back to preseason values within 2 months. Dust was also obtained from the houses of 50 patients with acute or severe asthma. The results on these samples suggest that mite-allergic patients are more likely to have attacks in the fall at a time when their houses have greater than 10 micrograms AgP1Eq per gram of dust. The magnitude of changes observed seasonally within individual houses and of differences between houses within a close geographic area suggests that interpretation of the relationship between allergic symptoms and mite-allergen exposure will require measurement of mite-allergen levels in individual houses.

Asthma↗
PubMed1987

House dust sensitivity and environmental control.

Allergy to foreign proteins in house dust is extremely common. Despite the fact that immunotherapy with house dust extract has been utilized for over sixty years, environmental control is still infrequently employed as a therapeutic measure. In this article the major allergen content of house dust is defined and strategies for decreasing the levels of these allergens in homes are described.

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

Species-specific allergens from the salivary glands of Triatominae (Heteroptera:Reduviidae).

We investigated allergenic cross-reactivity among species of the blood-feeding insects of the subfamily Triatominae. By skin testing, patients allergic to either Triatoma protracta or T. rubida gave positive responses only to the respective salivary antigen. RAST-inhibition experiments demonstrated that binding of IgE antibodies to T. protracta antigen was not inhibited by salivary extracts from T. rubida, T. cavernicola, T. rubrofasciata, or Rhodnius prolixus. The same level of species specificity was found for IgE antibodies to T. rubida. By direct RAST, no T. rubida positive serum bound T. protracta antigen, and 29 of 30 T. protracta positive sera failed to bind T. rubida. One serum from a T. protracta-allergic patient contained IgE antibodies to both T. protracta and T. rubida. RAST-inhibition experiments demonstrated that these antibodies did not cross-react and that this person had separate species-specific antibodies to T. protracta and T. rubida antigens. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of salivary extracts demonstrated that the lower molecular weight bands that contain the antigens responsible for human allergic reactions differed in number and size in all species tested. These studies demonstrate species specificity for the allergic response to Triatoma and stress the importance of accurate insect identification and the need for species-specific antigens for diagnosis and immunotherapy.

Allergens↗
PubMed1986

Identification and partial purification of species-specific allergens from Triatoma protracta (Heteroptera:Reduviidae).

This article describes the immunochemical characterization of allergens from Triatoma protracta, a hematophagous insect that causes IgE-mediated anaphylactic reactions when it bites sensitized allergic persons. Comparison of the allergenic potency of T. protracta salivary gland extract, thoracic and abdominal hemolymph, and a whole body extract by RAST inhibition demonstrated that salivary glands were the main source of T. protracta allergens. Concentrated salivary gland extracts were purified by gel filtration and isoelectric focusing. Fractions were tested for allergenic activity by RAST inhibition and for protein purity by polyacrylamide gel electrophoresis and immunoelectrophoresis. Two protein peaks were obtained on gel filtration. The high-molecular-weight peak contained a 70,000 MW protein/glycoprotein that had little allergenic activity. The low-molecular-weight peak comprised six proteins, molecular weight 17,000 to 25,000, and T. protracta allergen(s) eluted in parallel with this peak. These proteins were resolved by isoelectric focusing, and two fractions, pI 6.7 to 7.3 and pI 8.2, contained most of the allergenic activity. By RAST, 25/28 sera from T. protracta-allergic patients contained IgE antibody to these fractions, suggesting that they were major allergens. Each fraction demonstrated a single precipitin arc on immunoelectrophoresis and two bands, molecular weight 18,000 to 20,000, on gel electrophoresis. Cross-inhibition radioimmunoassays demonstrated that each fraction completely inhibited binding of the other fraction to IgE antibody, suggesting that they contained different isoelectric forms of the same allergen.

Allergens↗
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↗
PubMed1984

Zymodeme and species specificities of monoclonal antibodies raised against Trypanosoma cruzi.

A series of hybrid cell lines was generated by the fusion of Sp2/0 myeloma cells with spleen cells from BALB/c mice that had been immunized or infected with Trypanosoma cruzi zymodemes (Z1, Z2, Z3 ). Four immunoglobulin isotypes, IgM, IgG1, IgG2a and IgG3 were represented amongst the monoclonal antibodies secreted by 22 hybridoma clones. On indirect immunofluorescence (IFAT) antibodies bound to flagellum, cytoplasm, cell membrane or stained the whole organism. Two antibodies were epimastigote-specific. Enzyme-linked immunosorbent assays (ELISA) and a dot immunobinding test were used to evaluate the zymodeme and species specificities of 13 antibodies: four reacted with all T. cruzi zymodemes tested, two reacted strongly with all except Z1, two predominantly with Z1, two predominantly with Z2, and three predominantly with Z3 . Two IgM antibodies cross reacted with Trypanosoma rangeli, T. brucei, Leishmania mexicana, L. braziliensis and L. donovani. Five antibodies were used in a preliminary immunobinding test, performed blindly, to compare monoclonal reactivities and zymodeme groups. The results suggested a correlation between the two methods of characterization. Anti-T. cruzi monoclonal antibodies are considered to have important applications to epidemiological studies and the improved diagnosis and prognosis of Chagas' disease.

Animals↗