Measurement of absolute amounts of antigen-specific human IgE by a radioallergosorbent test (RAST) elution technique.

A technique for the absolute quantification of antigen-specific human IgE is described. It employs elution of a calculable amount of antigen-specific IgE from an allergosorbent-antibody complex by means of alkaline pH treatment, followed by measurement of the IgE content of the eluate with a modified radioimmunosorbent test (RIST). With this method IgE antibody directed against the benzylpenicilloyl determinant of penicillin (BPO) was measured quantitatively in sera from seven penicillin allergic patients. IgE specific for ragweed antigen E was measured in sera from 33 ragweed allergic patients. Values obtained for IgE anti-BPO ranged from 19 to 1806 ng/ml and comprised from 1.3 to 27.5% of total serum IgE. Values of IgE anti-antigen E ranged from 9 to 1807 ng/ml, comprising from 3 to 84% of total serum IgE. Excellent correlation (r = 0.99; p less than 0.001) was obtained for both antigen systems between values determined by the RAST elution technique and by simple RAST assay with interpolation from a reference serum of known specific IgE content as determined by the elution technique may be needed only for primary standardization of reference sera.     

Quantitation of specific igg,iga, and igm antibodies directed against four species of basidiomycetes

Specific IgG, IgA, and IgM antibodies to aqueous extracts of Coprinus quadrifidus, Pleurotus ostreatus, Calvatia cyathiformis, and Psilocybe cubensis were assessed using an enzyme linked immunosorbent assay (ELISA) in basidiomycete radioallergosorbent test (RAST) positive atopics (Gr 1), RAST negative atopics (Gr 2), and RAST negative, non-atopics (Gr 3). ELISA values are presented as mean optical density ± sem. For C. quadrifidus, elevated specific IgA levels (0.33 ± 0.08, p=0.02) were shown in Gr 1, as compared with Gr 2 (0.129 ± 0.04) and Gr 3 (0.163 ± 0.02). For P. ostreatus, specific IgA levels (0.534 ± 0.15) were also elevated (p=0.003) in Gr 1, when compared with Gr 2 (0.389 ± 0.01) and Gr 3 (0.121 ± 0.03). For C. cyathiformis and P. cubensis, specific IgA levels in Gr 1 were higher than those in Gr 2 and Gr 3, however, these were not significantly elevated. For P. cubensis, specific IgM levels were elevated (p=0.03) in Gr 2 (0.666 ± 0.081) when compared with Gr 1 (0.505 ± 0.056) and Gr 3 (0.413 ± 0.045), respectively. No other differences were observed among the groups in any species tested. These data confirm that isotypes, other than IgE, are produced against Basidiomycetes, also, RAST positive, atopic subjects have a tendency to make higher levels of specific IgA, than RAST negative subjects.     

Measurement of IgG blocking antibodies by interference in the radioallergosorbent test

We previously found that sera of patients immunized with ragweed pollen extract contained a factor that interfered with the binding of IgE antibodies to solid-phase allergens in the radioallergosorbent test (RAST). We now describe an assay, RAST interference, to measure this factor, and we present evidence that the factor is IgG blocking antibody. Sera from immunized allergic patients were heated at 56 degrees C for 4 hr to destroy heat-labile Fc determinants on IgE and were tested for their ability to prevent binding of additional IgE antibody to solid-phase allergens in the RAST. Eight of 10 sera from allergic immunized patients gave RAST interference dose-response curves that did not differ from the arbitrary standard. The factor causing interference showed specificity for the immunizing antigen, was heat-stable, eluted from Sephadex G-200 in the 7S peak, was present only in sera of immunized patients, and rose after initiation of immunization. These results indicated that RAST interference can be used to measure IgG blocking antibodies with the same reagents employed for the measurement of IgE antibodies, provided the antiserum to IgE is specific for the heat-labile FC determinants on IgE.     

Identification of specific IgE binding proteins in Castor bean (Ricinus communis) pollen obtained from different source materials

Allergenic components of Ricinus communis pollen obtained from different stages of inflorescence, different time intervals, different years and places were studied by immunoblot analysis. Proteins separated by SDS-PAGE and transferred to NC were identified using pooled sera from 15 skin and RAST positive patients. The IgE binding components in M.W. range of 14 to 70 kD were identified. The protein fractions of 70, 66, 64, 60, 50, 45, 36, 22 and 14 kD are the most prominent allergenic bands. Six samples collected during same pollination season from the same place showed similar allergenic profile. Of the samples collected from different stages of inflorescence, pollen of immature buds showed only three bands as compared to 18 from mature buds and flowers. Variability was seen in the IgE binding components of pollen stored for different years and obtained from different geographic regions of India. The IgE binding pattern of fifteen sera were heterogenous. The number of bands identified by different sera varied from 3 to 18. Two protein components of 66 and 36 kD were recognised by 14 (93.3%) of the 15 sera studied. The result suggests that there exists variations in the specific IgE binding pattern in pollen samples of Castor Bean, obtained from difference source materials.     

Use of solid-phase immunoenzyme analysis for determining allergen-specific IgE antibodies

An ELISA system for the detection of allergen-specific IgE antibodies to ragweed allergen has been developed. The system is highly sensitive and specific. Ragweed pollen allergen has been obtained by the dialysis of water-soluble extract through a kidney membrane. The high molecular fraction of ragweed allergen, showing the whole of the allergenic activity detected by skin tests in untreated patients, has been used for coating polystyrene assay plates. To detect IgE antibodies to ragweed allergen, the conjugate of sheep anti-IgE antibodies with horse-radish peroxidase has been used. The level of allergen-specific IgE antibodies has been determined on the basis of the data on the optical density of the samples in comparison with that of the normal sera. The correlation factor of the results obtained in the assay of specific IgE antibodies with the newly developed assay system and with the commercial kit Phadezyme RAST manufactured by Pharmacia AB (Sweden) has proved to be 0.82 at n = 39, p less than 0.01, while the variation factor in the reproduction of the assay results has proved to be 12% at n = 40.     

Fluorometric enzyme-linked immunosorbent assay for the measurement of IgE antibody to mite Dermatophagoides farinae

We have developed a fluorometric enzyme-linked immunosorbent assay for measuring IgE antibody to Dermatophagoides farinae. Polystyrene microplates were coated with proteins extracted from the mites. The IgE antibody which attached to the solid-phase antigen was detected by anti-IgE antibody conjugated with beta-galactosidase. Four-methylumbelliferyl-beta-D-galactoside was used as the enzyme substrate and the fluorescence intensity of the reaction product was measured. The antibody levels determined by this method well correlated with those determined by the radioallergosorbent test (RAST). This method is simpler and less expensive to carry out than the RAST when dealing with a large number of serum specimens for seroepidemiological studies of asthma and nasal allergy.     

Detection of IgG and IgE antibodies to Aspergillus fumigatus in human sera by immunogold assay

An immunogold assay (IGA) was developed to detect IgG and IgE antibodies to Aspergillus fumigatus. Sixteen sera from patients with allergic bronchopulmonary aspergillosis (ABPA), aspergilloma, and normal controls were studied. All sera were also evaluated for antibodies against A. fumigatus by biotin-avidin linked enzyme immunosorbent assay (BALISA) and by agar gel double diffusion method. A. fumigatus specific IgG and IgE antibodies could be detected by IGA in all the patients' sera but not in the sera of normal controls. Both IgG and IgE antibodies to A. fumigatus could be demonstrated in all the sera by BALISA and normal controls showed only low levels of these antibodies. There was a positive correlation between the degree of reactivity detected by IGA, the BALISA titer and the precipitins by agar gel diffusion. It can be concluded that IGA is a reliable, sensitive and simple method capable of detecting both IgG and IgE antibodies against A. fumigatus in patient serum.     

Identification and partial characterization of the allergenic proteins of Ricinus communis L. pollen - a new approach

The pollen of Ricinus communis L., a potentially allergenic plant, was extracted to identify the allergenic determinants responsible for causing respiratory disorders. The soluble proteins were extracted and subjected to ammonium sulphate precipitation at 80% saturation and the total protein separated on 12% SDS-Polyacrylamide gel. In order to avoid the time consuming and expensive biochemical methods of column chromatography, each band was directly recovered from the gel by electroelution and the allergenic proteins identified directly by skin tests, without the necessity of Phadezym RAST or ELISA inhibition by reaction with serum IgE, the general procedure to identify the allergens. The fourth and the fifth band in the protein profile of R. communis pollen, RC4 (77 kD) and RC5 (66 kD) were the two major allergenic components. RC3 (91 kD) also induced a considerable amount of reactivity in sensitive patients. Contrary to the earlier reports of protein bands of R. communis ranging from 14 kD to 70 kD, 4 bands above 70 kD i.e. RC1 (123 kD), RC2 (97 kD), RC3 (91 kD) and RC4 (77 kD) are reported here for the first time. Immunodiffusion analysis with pooled sera of patients sensitive to the total extract also revealed similar results.     

Comparison of allergenic potency of five batches ofAlternaria alternata for preparation of reference standard

Five batches of 34-016 isolate were grown separately on synthetic revised tobacco medium for 28 days. Extracts of the mycelia were prepared and their biochemical and immunological properties were examined. The extracts had similar isoelectric focussing (IEF) patterns. In crossed-radioimmuno-electrophoresis (CRIE) using human atopic sera, each showed two dominant and two to three minor allergens. In direct radioallergosorbent (RAST) and RAST inhibition tests with human atopic sera and passive cutaneous anaphylaxis (PCA) tests with mouse IgE, all samples were of similar potency. In IgE immunoblots of sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) gels, each extract showed strongly reactive bands at 16, 18, 30, 33 and 59–100 kDa MW. These results indicate that a reference preparation ofA. alternata suitable for standardization purposes can be obtained from any batch of 34-016 isolate.     

House-dust mite sensitivity among rural and urban asthmatics of West Bengal, India: a comparison

House-dust mite allergy is a fairly common problem in West Bengal among individuals sensitive to dust inhalation. House-dust mites belonging to the genusDermatophagoides are abundant in the homes of asthmatic patients residing in urban as well as rural areas of West Bengal. The frequency of positive skin reaction to different dust-related allergens tested was higher (χ²=5.4777, df = 1;P < 0.05) among patients of urban areas compared with that among the patients of rural areas. Urban patients showed more frequent skin reaction towards cockroach allergen, while rural patients are more sensitive to hay-dust allergen and these are very much related to their local environmental conditions. Analysis of radioallergosorbent test (RAST) results against house dust (HD) and mites reveal that 73 and 90% patients of both urban and rural areas responded positively towardsDermatophagoides pteronyssinus (DP) andDermatophagoides farinae (DF) antigens, respectively. The present study indicates no significant difference in house-dust mite sensitivity and mite levels in homes among the rural and urban asthmatics of West Bengal, India as evidenced from the results of analysis of dust samples, allergy skin test and detection of mite-specific IgE antibodies by RAST.     

The role of phadiatop in the screening of respiratory allergy

Phadiatop is a new in vitro screening test for respiratory allergy. This test, based on the RAST procedure, detects in serum, the presence of specific IgE to a mixture of common inhalent allergens. Among 70 patients (26 children and 44 adults) consulting for respiratory syndrome, Phadiatop was positive in 31 cases. There were a good correlation between this new test and skin tests (59% for adults and 92% for children), total IgE (70% for adults and 65% for children) and RAST (93% for adults and 96% for children). Phadiatop, with a specificity of 100%, a sensitivity of 82% (76% for adults and 92% for children) and an efficiency of 90% (86% for adults and 96% for children), is a more accurate test than total IgE and could be an excellent in vitro screening test for respiratory allergy.     

Skin testing versus radioallergosorbent testing for indoor allergens

BACKGROUND: Skin testing (ST) is the most common screening method for allergy evaluation. Measurement of serum specific IgE is also commonly used, but less so by allergists than by other practitioners. The sensitivity and specificity of these testing methods may vary by type of causative allergen and type of allergic manifestation. We compared ST reactivity with serum specific IgE antibodies to common indoor allergens in patients with respiratory allergies. METHODS: 118 patients (3 mo-58 yr, mean 12 yr) with allergic rhinitis and/or bronchial asthma had percutaneous skin testing (PST) supplemented by intradermal testing (ID) with those allergens suspected by history but showed negative PST. The sera were tested blindly for specific IgE antibodies by the radioallergosorbent test (Phadebas RAST). The allergens were D. farinae (118), cockroach (60), cat epithelium (90), and dog epidermal (90). Test results were scored 0-4; ST >/= 2 + and RAST >/= 1 + were considered positive. RESULTS: The two tests were in agreement (i.e., either both positive or both negative) in 52.2% (dog epidermal) to 62.2% (cat epithelium). When RAST was positive, ST was positive in 80% (dog epidermal) to 100% (cockroach mix). When ST was positive, RAST was positive in 16.3% (dog epidermal) to 50.0% (D. farinae). When RAST was negative, ST was positive in 48.5% (cat epithelium) to 69.6% (D. farinae). When ST was negative, RAST was positive in 0% (cockroach) to 5.6% (cat epithelium). The scores of ST and RAST showed weak to moderate correlation (r = 0.24 to 0.54). Regardless of history of symptoms on exposure, ST was superior to RAST in detecting sensitization to cat epithelium and dog epidermal. CONCLUSION: For all four indoor allergens tested, ST was more sensitive than RAST. When both tests were positive, their scores showed poor correlation. Sensitizations to cat epithelium and dog epidermal are common, even in subjects who claimed no direct exposure.     

Purification and characterization ofFus sI3596, a 65 kd allergen ofFusarium solani

A component ofFusarium solani (F. solani), identified as the major allergen,Fus sI₃₅₉₆ ^* was purified to homogeneity from culture filtrate (CF) by means of anion-exchange column chromatography, gel filtration and FPLC. The homogeneity ofFus sI₃₅₉₆ ^* was assessed by IEF, PAGE, SDS-PAGE (non-reducing), immunoblot and HPLC.Fus sI₃₅₉₆ ^* was isolated as a glycoprotein of MW 65 kd and pI 3.6. The IgE ELISA-inhibition assay after periodate treatment of the fraction showed a lower IgE binding capacity suggesting involvement of carbohydrate moiety in IgE binding reactions of the allergen. Peptide fragments ofFus sI₃₅₉₆ ^* obtained after CNBr and trypsin treatment were analysed by immunoblotting for their allergenicity. This study indicated that there could be at least 3 allergenic determinants in the major allergen,Fus sI₃₅₉₆ ^* ofF. solani CF.Abbreviations DEAE diethyl aminoethyl - HPLC high performance liquid chromatography - SDS sodium dodecyl sulphate - PBS-Tween phosphate buffer saline containing 0.1% tween - DTT dithiothreitol - TFA triflouroacetate - FPLC fast protein liquid chromatography     

Detection of True IgE-expressing Mouse B Lineage Cells

B lymphocyte immunoglobulin heavy chain (IgH) class switch recombination (CSR) is a process wherein initially expressed IgM switches to other IgH isotypes, such as IgA, IgE and IgG. Measurement of IgH CSR in vitro is a key method for the study of a number of biologic processes ranging from DNA recombination and repair to aspects of molecular and cellular immunology. In vitro CSR assay involves the flow cytometric measurement surface Ig expression on activated B cells. While measurement of IgA and IgG subclasses is straightforward, measurement of IgE by this method is problematic due to soluble IgE binding to FcεRII/CD23 expressed on the surface of activated B cells. Here we describe a unique procedure for accurate measurement of IgE-producing mouse B cells that have undergone CSR in culture. The method is based on trypsin-mediated cleavage of IgE-CD23 complexes on cell surfaces, allowing for detection of IgE-producing B lineage cells by cytoplasmic staining. This procedure offers a convenient solution for flow cytometric analysis of CSR to IgE.     

Diagnosis of <Emphasis Type="Italic">Chenopodium album</Emphasis> allergy with a cocktail of recombinant allergens as a tool for component-resolved diagnosis

Chenopodium album pollen is one of the main sources of pollen allergy in desert and semi-desert areas and contains three identified allergens, so the aim of this study is comparison of the diagnostic potential of C. album recombinant allergens in an allergenic cocktail and C. album pollen extract. Diagnostic potential of the allergenic cocktail was investigated in 32 individuals using skin prick test and obtained results were compared with the acquired results from C. album pollen extract. Specific IgE reactivity against the pollen extract and allergenic cocktail was determined by ELISA and western blotting tests. Inhibition assays were performed for the allergenic cocktail characterization. The exact sensitization profile of all patients was identified which showed that 72, 81 and 46% of allergic patients had IgE reactivity to rChe a 1, rChe a 2 and rChe a 3, respectively. Almost all of C. album allergic patients (30/32) had specific IgE against the allergenic cocktail. In addition, there was a high correlation between IgE levels against the allergenic cocktail and IgE levels against the pollen extract. The allergenic cocktail was able to completely inhibit IgE binding to natural Che a 1, Che a 2 and Che a 3 in C. album extract. In addition, positive skin test reactions were seen in allergic patients that tested by the allergenic cocktail. The reliable results obtained from this study confirmed that the allergenic cocktail with high diagnostic potential could be replaced with natural C. album allergen extracts in skin prick test and serologic tests.     

Sex differences in heritability of sensitization to<Emphasis Type="Italic"> Blomia tropicalis</Emphasis> in asthma using regression of offspring on midparent (ROMP) methods

A genetic basis for asthma- and atopy-related quantitative traits, such as allergen-specific immunoglobulin E (IgE) levels, has been suggested by the observed familial aggregation of these traits in temperate climates. Less information is available for tropical climates, where different allergens may predominate. Sensitivity to the mite Blomia tropicalis is related to asthma in tropical climates, but heritability of B. tropicalis sensitivity and the impact of age, sex, and other environmental covariates on heritability have not been widely explored. Total and specific IgE levels were measured by immunochemiluminescent assay in 481 members of 29 Barbadian families (comprised of 340 parent-offspring trios or pairs) ascertained through two asthmatic siblings. Trait heritability was estimated using regression of offspring on mid-parent (ROMP) and pairwise correlation analysis of unadjusted IgE levels and on residual values after adjustment for covariates. Heritability of IgE levels to the major antigen of B. tropicalis (Blo t M) estimated by ROMP in 180 complete parent-offspring trios was 0.56. Heritability was consistently greater for male offspring than for female offspring. Similar sex-specific patterns were observed for specific IgE to Dermatophagoides pteronyssinus and total IgE levels and were relatively unaffected by adjustment for covariates. Pairwise correlational analyses of specific and total IgE levels showed similar results. Moderate heritability of Blo t M IgE levels was detected in these Barbadian families and was greater for sons than daughters. Adjustment for covariates had minimal impact. This suggests that future investigations of genetic determinants of IgE levels should include approaches that allow for potential sex differences in their expression.     

Allergy to insect stings. IV. Diagnosis by radioallergosorbent test (R.A.S.T.)

Radioallergosorbent tests (RAST(s)) have been developed and assessed for the diagnosis of insect hypersensitivity by using a purified allergen from honeybee venom, phospholipase A, and crude yellow jacket venom. Sera from 193 patients positive both by history and skin test to one of these insects were compared with various groups of control sera. Eighty percent of sera from skin test-positive patients were RAST positive; positive RAST were found in 16% of sera tested from skin test-negative patients. A highly positive RAST correlates well with a positive skin test and clinical sensitivity, but serum IgE is not measurable in many patients with mast cell or basophil bound antibody. Since biologically important reactions of antigen with IgE require that the antibody be cell bound, skin testing would be preferred to RAST if one were limited to a single test for the diagnosis of insect allergy.     

Bioluminescent assay of ATPase activity in embryonic material using firefly luciferase

The continuous bioluminescent assay of ATP has been adapted to the study of Mg²⁺-dependent ATPases, including the (Na⁺,K⁺) pump, in amphibian tissues. A discrete bioluminescent assay procedure for ATPase has also been developed. Components of the firefly luciferase assay reagent modify the observed ATPase activity but this can be circumvented by performing discrete instead of continuous measurements of enzyme activity. In assays with commercial ATPase preparations the continuous bioluminescent assay procedure gave ATPase activities 2.2-fold lower than obtained with the discrete procedure. In Xenopus oocyte or egg homogenates, in contrast, the total ATPase activity measured is stimulated eight times by the luciferase reagent, mainly through an unexplained activation of a Mg²⁺-independent ATPase. In other tissues, such as Xenopus brain homogenates, both the continuous and discrete monitoring procedures are equally suitable for the determination of ATPase activity.     

Identification of Glycycometus malaysiensis (for the first time in Brazil), Blomia tropicalis and Dermatophagoides pteronyssinus through multiplex PCR

Blomia tropicalis and Dermatophagoides pteronyssinus play an important role in triggering allergy. Glycycometus malaysiensis causes IgE reaction in sensitive people, but is rarely reported in domestic dust, because it is morphologically similar to B. tropicalis making the identification of these species difficult. The identification of mites is mostly based on morphology, a time-consuming and ambiguous approach. Herein, we describe a multiplex polymerase chain reaction (mPCR) assay based on ribosomal DNA capable to identify mixed cultures of B. tropicalis, D. pteronyssinus and G. malaysiensis, and/or to identify these species from environmental dust. For this, the internal transcribed spacer 2 (ITS2) regions, flanked by partial sequences of the 5.8S and 28S genes, were PCR-amplified, cloned and sequenced. The sequences obtained were aligned with co-specific sequences available in the GenBank database for primer design and phylogenetic studies. Three pairs of primers were chosen to compose the mPCR assay, which was used to verify the frequency of different mites in house dust samples (n?=?20) from homes of Salvador, Brazil. Blomia tropicalis was the most frequent, found in 95% of the samples, followed by G. malaysiensis (70%) and D. pteronyssinus (60%). Besides reporting for the first time the occurrence of G. malaysiensis in Brazil, our results confirm the good resolution of the ITS2 region for mite identification. Furthermore, the mPCR assay proved to be a fast and reliable tool for identifying these mites in mixed cultures and could be applied in future epidemiological studies, and for quality control of mite extract production for general use.

     

Determination of Specific Class E Immunoglobulins to Bet v 1 Birch Allergen by the Immuno-PCR Method

The aim of the work is the development of a method of detection of specific class E immunoglobulins (IgE) to the main Bet v 1 birch allergen based on immuno-PCR (iPCR). The recombinant Bet v 1 allergen was obtained in E. coli cells. Its ability to bind to specific IgE was confirmed by enzyme-linked immunosorbent assay (ELISA) using previously characterized sera of individuals with an allergic reaction to birch pollen and control sera in individuals, in which the reaction to this allergen is absent. Based on the obtained recombinant protein, the method of iPCR analysis of specific IgE to Bet v 1 was developed. It was demonstrated that iPCR sensitivity is comparable to ELISA sensitivity, and the titration curves of specific sera in iPCR (unlike those in ELISA) demonstrate a linear dependence; this makes the developed method preferable for quantitative estimation of specific IgE in sera as compared with ELISA.