Positive RAST Scores Research Articles

Polymorphisms of the CYP2C19 gene in Japanese patients with aspirin-exacerbated respiratory disease

Polymorphisms of the CYP2C19 gene in Japanese patients with aspirin-exacerbated respiratory disease

Comparison of 2 RAST scoring methods in assessing hypersensitivity to oak and birch pollen

Rationale Allergen specific IgE measured by the Immunocap™ system is typically reported in KIU/mL as well as in percent of a single standard (ASM system). Abnormal results in one scoring system may coexist with normal results in the other system. Methods 184 patients evaluated for allergic disease underwent serological testing for specific IgE. Results for pollens of the Fagales trees, oak ( Quercus alba) and birch ( Betula verrucosa) were examined with respect to RAST class scores using the CAP™ KIU/mL system and with the alternative scoring system (ASM). Results For both tree pollens, there were 11% more patients who had positive RAST scores utilizing the ASM system compared with the CAP system. High and very high CAP™ scores (>=levels 3) correlated well with ASM class (>=4 scores). However moderate (level 2) CAP™ scores could be either ASM RAST class 2 or 3, and negative (level 0) CAP™ scores were mostly ASM RAST class 0 but sometimes were class 1. Considering all patients with either oak or birch positive RAST scores, the proportion of RAST scores which were discordantly positive for only one Fagales tree was similar utilizing the 2 scoring methods. Conclusions For 2 tree pollens which characteristically elicit strong IgE responses, a higher proportion of positive results are noted when RAST results are scored using the ASM system, mostly due to ASM class 1 increases.

Meat allergy: investigation of potential allergenic proteins in beef.

The potential allergenic proteins in beef were investigated. The sera of ten beef-allergic patients suffering from atopic dermatitis and having a positive RAST score to beef, aged 3-18 years, were obtained from Yoshida Hospital in Japan, and five non-allergic individuals were subjected to this study. The sera of the ten patients reacted strongly to a beef extract, but not to pork and chicken extracts by both ELISA and immunoblotting. The sera of the five control subjects did not react to any of these meat extracts. Three bands having molecular masses of approximately 200 kDa, approximately 67 kDa and approximately 60 kDa were observed by immunoblotting after SDS-PAGE. Two fractions of the beef extract from a Sephadex-gel (G-200) filtration column strongly reacted with the sera of the beef-allergic patients by ELISA and immunoblotting: one fraction had the approximately 67 kDa component and the other had the approximately 200 kDa and approximately 60 kDa components. One of them (approximately 67 kDa) was confirmed to be bovine serum albumin (BSA) by an analysis of the N-terminal amino acid sequence. We could not identify the others by sequencing, but the approximately 200 kDa and approximately 60 kDa components were presumed to be glycoproteins. Bovine gamma (BGG:globulin M.W. approximately 160 kDa) is a glycoprotein and has several subunits. The beef-allergic patients showed strong reactivity to the approximately 200 kDa and approximately 60 kDa components of pure BGG by immunoblotting. Inhibition-ELISA showed that pure BGG preparations strongly inhibited the binding of sera from the beef-allergic patients to the beef extract. These results suggest that the approximately 200 kDa, approximately 67 kDa and approximately 60 kDa components in the beef extract had strong allergenicity: approximately 67 kDa was BSA, and approximately 200 kDa and approximately 60 kDa were presumably aggregated BGG and it's heavy chain, respectively.

A comparison of skin prick tests, intradermal skin tests, and RASTs in the diagnosis of cat allergy

Background: Skin testing and RASTs are the most commonly used methods for the diagnosis of allergy. Questions remain, however, as to the accuracy of these tests, particularly with regard to the role of intradermal skin tests (IDSTs) in the evaluation of respiratory allergy. Objective: The purpose of this study was to determine the predictive value of skin prick tests (SPTs), IDSTs, and RASTs in the diagnosis of cat allergy. Methods: Patients were challenged with a well-characterized cat exposure model after evaluation by history, SPTs, IDSTs (if SPT results were negative), and RASTs. All patients were evaluated with respect to their upper respiratory responses, although only those patients with asthma were included in the analysis of lower airway responses. Challenge results were considered positive if the mean upper respiratory symptom score was 0.5 or more, the mean lower respiratory symptom score was 0.4 or more, or the maximum fall in FEV 1 value was 15% or more. Results: One hundred twenty patients were evaluated. SPT values were positive in 81 patients; of the remaining 39 patients, IDST values were positive in 26 patients. RASTs were performed in 89 patients; the values were positive in 45 of 51 patients with a positive SPT value and were negative in all patients with a negative SPT value. When any positive challenge outcome was considered, positive challenge results were seen in 38 of 41 patients with a positive SPT score, in 10 of 39 patients with a negative SPT score, in 6 of 26 patients with a positive IDST score, in 4 of 13 patients with a negative IDST score, in 27 of 27 patients with a positive RAST score, and in 12 of 44 patients with a negative RAST score. Conclusion: Although both SPT and RAST values exhibited excellent efficiency in the diagnosis of cat allergy, IDST scores added little to the diagnostic evaluation. (J Allergy Clin Immunol 1999;103:773-9.)

Regulation of peripheral blood mononuclear cell responses to Dermatophagoides farinae by substance P in patients with atopic dermatitis.

Neuropeptides mediate stress-induced cutaneous inflammation such as atopic dermatitis. The effect of substance P on proliferation and cytokine mRNA expression of peripheral blood mononuclear cells in response to Dermatophagoides farinae (Der f) was studied in atopic dermatitis patients with positive RAST scores to Der f. Upon stimulation with Der f peripheral blood mononuclear cells from patients proliferated in a B7-dependent (CD80- and CD86-dependent) manner, while those from the patients with negative scores, nonatopic eczematous dermatitis patients or normal individuals, did not. Based on the reactivity of normal individuals, atopic dermatitis patients with a stimulation index greater than 1.8 were tentatively defined as high responders, who comprised two-thirds of the patients. Proliferation in high responders was associated with upregulation of IL-2 mRNA expression and induction of IL-5 mRNA expression. Substance p at 10(-10) to 10(-8) M promoted the Der f-induced proliferation when added at the start of culture and upregulated IL-10 MRNA expression while downregulating IL-5 mRNA expression. Our results suggest that substance P modifies immune responses of atopic T cells to Der f by promoting proliferation and altering cytokine profiles, and thus modulates the clinical manifestations of atopic dermatitis.

Age-related changes of IgE-mediated allergic reaction in patients with late onset asthma--relationship between IgE-mediated allergy and age at onset

We examined age-related changes in the IgE-mediated allergic reaction in patients with late onset asthma, whose asthma first occurred at over 40 years. 1. The number of patients with a high serum IgE level (over 300 IU/ml) was larger in patients with an age of onset between 40 and (40-49 years group) and in patients older than 60 at age of onset (60-year group) than in patients with an age of onset between 50 and 59 (50-59 year group). 2. A positive RAST score to house dust mite (HDm) allergen was more frequently found in the 40-49 year group and in the 60- year group than in the 50-59 year group. Frequency of positive RAST score to HDm in the 50-59 year group was significantly lower (p < 0.01) than in early-onset asthma patients (age at onset less than 39 years). 3 Frequency of family history of asthma in the 50-59 years group was high, being equal to that of early-onset asthma patients. 4 In the 50-59 year group, the frequency of severe asthma was comparatively higher than that of the other groups. The frequency of IgE-mediated allergic reaction changed in regard to age of onset of asthma, and allergic reactions in late-onset asthma partially resembled those of early-onset asthma. These results suggest that an atopic constitution is related to the onset of bronchial asthma in the elderly.

Association of asthma with serum IgE levels and aging. Bronchoalveolar cells and the release of histamine and leukotrienes, LTC4 and LTB4, from leucocytes.

Association of age and serum IgE levels with pathophysiology of asthma was examined in 64 patients with asthma. Positive RAST scores of 2+ or more to inhaled allergens were significantly higher in patients with high serum IgE than in those with low serum IgE in 4059 year-olds. The proportion of BAL lymphocytes was significantly higher in patients over age 60 with high serum IgE compared with those between 20 and 39 and between 40 and 59 with either high or low serum IgE. The release of histamine or leukotriene C4, from leucocytes was significantly higher in patients with high serum IgE than in those with low serum IgE in 20-39 (both histamine and LTC4) and over 60 year-olds (histamine).

IgE-Mediated Sensitization to English Plantain Pollen in Seasonal Respiratory Allergy: Identification and Partial Characterisation of Its Allergenic Components

Characterisation by SDS-PAGE immunoblotting of plantain pollen extract showed that components of 16,000-20,000 M(r) were frequently reactive with IgE antibody in the sera of subjects with seasonal respiratory allergy. Other, more weakly IgE-binding allergens were seen in the range of 40,000-60,000 M(r). HPLC followed by RAST inhibition demonstrated that components of approximately 17,000 M(r) were also responsible for much of the IgE-binding activity of the extract. These components appeared to have pI values between 4.5 and 5.2. RAST inhibition showed that there were no common IgE-binding epitopes in grass pollen and plantain pollen extracts, indicating that skin test responses should not necessarily be interpreted in terms of cross-reaction. 82 subjects with a clinical history of seasonal, respiratory allergy were screened in a skin prick test survey. 28% were skin test positive to plantain pollen extract. The frequency of positive skin test reactions to plantain pollen extract was greater than that to Betula (23%) and Artemisa (16%), both which are considered to be important allergens. In a larger survey positive RAST scores to plantain pollen were given by 34% of sera from subjects with respiratory allergy. Plantain pollen sensitivity should therefore be considered during diagnosis of seasonal allergy.

An assay to measure antigen-specific immune complexes in food-allergy patients

An allergen- and isotype-specific assay to quantify the presence of serum immune complexes is described. This assay is based on a two-site recognition system so that only molecular complexes containing both antigen and antibody are counted. In this study affinity-purified antibodies to egg and milk whey were used on paper discs in conjunction with a soluble, labeled anti-immunoglobulin (IgE or IgG specific). To evaluate the assay, immune complexes were prepared in vitro by mixing antigen at different concentrations with serum from a patient with high levels of antibody. Complexes were detectable over a 5 log range of antigen concentration. The lower limit of sensitivity of the assay was estimated to be 5.8 ng of complexed IgE per milliliter of patient serum. To determine if the assay could detect natural in vivo-formed complexes, sera from patients with positive RAST scores to egg white or milk were selected for a preliminary study. Three of the nine egg white-positive sera and two of the nine milk-positive sera were found to contain significant levels of IgE immune complexes. The versatility and sensitivity of the assay should now make it feasible to design experiments to elucidate the role, if any, of circulating immune complexes in the etiology of food allergy.

Occupational allergy due to inhalation of ipecacuanha dust.

A number of workers packing ipecacuanha tablets were complaining of allergic symptoms. Skin-prick tests, RAST and an assessment of clinical history by interview were used to confirm the presence of work-related allergy. Specific IgE antibodies to ipecacuanha were detected and the occurrence of antibodies correlated with the incidence of allergic symptoms. The individuals with positive RAST scores had been employed, on average, longer than those with negative scores. It was found that atopy did not predispose the workers to work-related allergy and that there was no correlation between smoking and respiratory symptoms in this population.

Relationship of allergen-specific IgE antibodies, skin prick tests and allergic disorders in unselected adolescents.

The relationship between serum levels of allergen-specific IgE (RAST) and skin prick test reactivity and allergic disorders was evaluated in 137 subjects randomly selected from an adolescent population. All subjects were prick tested with six common allergens, interviewed and physically examined. In addition, serum was collected for RAST analysis with three to six allergens. At least one positive RAST result (score 1-4) was observed in 40% and at least two positive RASTs in 22% of the subjects. Boys experienced more RAST reactions and generally with higher scores than girls. For instance, 26% of boys but only 11% of girls were RAST positive to timothy grass pollen. The correlation between prick test and RAST results was better with pollens than with house dust and animal epithelia. When the test results were discordant, the skin test was usually positive and RAST negative. Many of the small skin reaction (weal diameter 3-4 mm) were accompanied by a negative RAST. Respiratory allergy was closely connected with both positive skin test and RAST reactivity, while atopic dermatitis was less related. In 17% of the adolescents positive skin tests and in 14% positive RASTs occurred in the absence of any allergic symptoms. We conclude that a positive RAST score 3-4 to inhaled allergens is a strong indicator of clinical allergy but low scores 1-2 are frequently found in healthy young people.

Animal dander allergy.

In a group of twenty-three atopic patients skin tests were performed with the dander allergens of horse, cat and guinea-pig, and with house dust and Timothy pollen allergens. A good agreement was observed between positive skin reactions and the results of RAST with these various allergens. In a number of cases, positive skin reactions were not related to the clinical histories. Likewise, positive RAST scores in several instances proved clinically meaningless. In patients with history-related skin reactions better correlation with RAST was observed. In such patients, skin reactions with photo-inactivated allergens remained strongly positive.