Sensitization and exposure to indoor allergens as risk factors for asthma among patients presenting to hospital.

To investigate the role of indoor allergens in adult patients with acute asthma, we conducted a case-controlled study on patients presenting to an emergency room. One hundred and fourteen patients and 114 control subjects were enrolled over a 1-yr period in Wilmington, Delaware. Sera were assayed for total IgE, and for IgE antibodies to dust mites, cat dander, cockroach, grass pollen, and ragweed pollen. Dust was obtained from 186 homes and assayed for dust mite, cat, and cockroach allergens. IgE antibodies to mite, cat, and cockroach were each significantly associated with asthma, and this association was very strong among participants without medical insurance and among African Americans. Among 99 uninsured participants, sensitization to one of the indoor allergens (> 200 RAST units) was present in 28 of 57 asthmatics and in one of 42 control subjects (odds ratio, 39; confidence interval, 9.4 to 166). For cat and cockroach the combination of sensitization and presence of allergen in the house was significantly associated with asthma. Furthermore, there was a strong inverse relationship between IgE antibodies to cat and to cockroach, and the risk of this sensitization was in large part restricted to homes or areas with high levels of allergen. Thirty-eight percent of the asthmatics, but only 8% of the control subjects, were allergic to one of the three indoor allergens, and had high levels of the relevant allergen in their houses (odds ratio, 7.4; confidence interval, 3.3 to 16.5).(ABSTRACT TRUNCATED AT 250 WORDS)

Environmental exposure to cockroach allergens: analysis with monoclonal antibody-based enzyme immunoassays.

Quantitative two-site monoclonal antibody (MAb)-based enzyme-linked immunoassays for two cockroach (CR) allergens, Bla g I and Bla g II, have been developed and used to measure allergen levels in house-dust samples. Dust collected from the CR-infested homes of two patients with asthma from Charlottesville, Va., demonstrated wide variation in the levels of Bla g I, depending on the location of dust collection. Dust from kitchen floors and cabinets contained 50-fold more allergen (mean, 10,755 U/gm of dust) than dust from bedrooms and upholstered furniture (mean, 204 U/gm). One hundred forty-five dust samples were collected from the bedrooms and living rooms of 22 children with asthma and 16 control subjects without asthma living in Atlanta, Ga. Twenty-seven of the 38 homes (17/22 children with asthma; 10/16 control subjects) had detectable Bla g I (4 to 1340 U/gm of dust). Bla g II levels were assayed in 40 kitchen, bedroom, and living room samples from homes in Wilmington, Del. Highest levels of Bla g II were detected in kitchen-floor dust (300 U/gm of dust). Additionally, approximately 20% of homes with no visual evidence of CR infestation had significant levels of Bla g II in at least one dust sample (greater than 4 U/gm of dust). Our results demonstrate that CR may be an occult allergen in homes. The kitchen appears to be the primary site of CR-allergen accumulation, but significant CR-allergen levels can also be found at other sites in the home. The MAb-based assays can be used for quantitation of environmental exposure to CR allergens.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification, quantitation, and purification of cockroach allergens using monoclonal antibodies.

A panel of murine IgG monoclonal antibodies (MAbs) was raised against German cockroach (CR) (Blattella germanica) extract and selectively screened to identify MAb directed against allergen(s) recognized by IgE antibodies. Sera from 28 CR-allergic patients were used as sources of IgE antibodies to detect allergens "presented" by the MAb. Four clones (10A6, 3G12, 8F4, and 1D4) produced MAb to allergen(s) that bound IgE antibodies. Quantitative radioimmunoassays were used to compare levels of the MAb-defined allergens in CR extracts. MAb 10A6 reacted with a cross-reacting allergen that was detected in 9/14 CR species, including Blattella, Periplaneta, Blatta, Leucophea, and Supella spp, at concentrations of 100 to 10,000 U/ml. In contrast, MAb 3G12, 8F4, and 1D4 were Blattella specific. The allergen defined by MAb 8F4 was purified by MAb affinity chromatography and size-exclusion by high-performance liquid chromatography. It is a 36 kd heat-sensitive protein, isoelectric point, 5.2 to 5.4. Allergen 10A6 was partially purified by isoelectric focusing and high-performance liquid chromatography. It is a heat-stable, acidic protein (isoelectric point 3.15). Based on comparison of their properties with properties of previously described CR allergens, the allergens defined by MAb 10A6 and 8F4 have been provisionally designated Blattella germanica allergen I (Bla g I) and Blattella germanica allergen II (Bla g II), respectively. Assays of six commercial CR skin test extracts demonstrated a 200-fold difference in Bla g I levels (4.7 to 1085 U/ml) and only two extracts that contained detectable Bla g II (248 and 324 U/ml). The results demonstrate that MAb can be used to identify and define CR allergens and that the strategy of the use of MAb as a first step in allergen analysis and purification can be very effective, especially for poorly characterized allergen extracts.

Epidemiology of acute asthma: IgE antibodies to common inhalant allergens as a risk factor for emergency room visits.

In recent years the morbidity and mortality of asthma has increased, although the etiology is still poorly understood. Most patients with asthma suffer acute attacks that are commonly treated in hospital emergency rooms (ER). In the present study, asthma in adults was studied with acute attacks as a marker for the disease; 102 patients first observed at a university hospital ER with acute airway obstruction were compared to 118 patients observed at the same ER with any diagnosis other than shortness of breath to evaluate allergy as a risk factor for asthma in adults. Sera were assayed for IgE antibody (Ab) to dust mites, cockroach, cat dander, and grass and ragweed pollen. The results demonstrate that in adults younger than 50 years of age, the prevalence of IgE Abs was fourfold greater among subjects with asthma than among control subjects (46/67 versus 12/81; odds ratio, 10.1; 95% confidence interval, 4.9 to 20.7). The population attributable risk for the presence of IgE Ab to one of the five allergens was greater than 50%. Among individuals older than 50 years of age, the prevalence of serum IgE Abs was not significantly increased among patients with acute airway obstruction. In the whole group, the prevalence of IgE Abs to different allergens demonstrated significant seasonal and socioeconomic differences, suggesting that the associated risk is related to exposure to those allergens. The results establish that, with acute attacks of asthma as a marker for adult asthma, the presence of serum IgE Abs to common inhalant allergens is a major risk factor.(ABSTRACT TRUNCATED AT 250 WORDS)

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)

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.

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.

Serum IgE antibodies to Trichophyton in patients with urticaria, angioedema, asthma, and rhinitis: development of a radioallergosorbent test.

A series of patients was identified who demonstrated immediate positive skin tests to intradermal Trichophyton extract. These skin responses did not correlate with other fungal skin tests and were present both in atopic and nonatopic patients. The individuals demonstrating positive immediate skin tests included patients with urticaria, angioedema, asthma, and/or rhinitis, as well as five of 34 normal control subjects. Most skin test positive individuals had a history of local fungal infection and clinical signs suggestive of fungal infection. By use of Trichophyton tonsurans extract linked to Sepharose as the immunosorbent, it was possible to measure IgE antibodies in 26/30 sera from skin test positive individuals. With strongly positive sera, RAST bound up to 30% of the radiolabeled anti-IgE added. The results confirm that most skin test positive individuals have IgE-mediated hypersensitivity to Trichophyton. These observations support the older view that absorption of dermatophyte allergen through the skin should be considered as a possible cause of allergic disease.