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Results for “Radioallergosorbent Test”

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PubMed1978

Detection of IgE insulin antibody with radioallergosorbent test.

An in vitro method for detecting IgE insulin antibody using the principle of the radioallergosorbent test (RAST) is described. In six patients with insulin allergy, the RAST values were higher than in normal persons or insulin-treated diabetics without insulin-allergy. No differences were observed between normal persons and insulin-treated diabetics without insulin-allergy. Moreover, it was observed that in one patient treated with highly-purified insulin, there was a gradual decrease of RAST value parallel to the radioinsulin binding activity and clinical allergic symptoms. The RAST value of insulin is slightly inhibited by non-IgE antibodies and is, therefore, a semiquantitative value. However, the RAST is simple to perform and reproducible; It therefore is very useful in the detection of IgE insulin antibodies.

Adult↗

PubMed1983

The development and validation of radioallergosorbent tests for the detection of specific human IgE antibody directed against laboratory animal urinary proteins.

Radioallergosorbent tests (RAST) using urinary proteins from mice, rats, guinea pigs and rabbits have been developed and used in the diagnosis of laboratory animal allergy (LAA). Of the 273 subjects tested, 15 had been previously diagnosed as laboratory animal allergic and 8 of these (53%) gave one or more positive RAST results. Of the 258 symptom-free individuals, only 9 (3.5%) had one or more positive RAST. Of these 9, 7 had previously worked with animals or had occupational exposure to the appropriate species; the remaining 2 individuals had only some pet exposure. RAST was, therefore, of value in the diagnosis of LAA. During the development of these RAST assays, several sources of potential error were identified. Modest titres of total IgE (600 IU/ml and above) were found to influence the specific RAST index observed and lead to false positive results. The presence of human IgG antibody specific for rabbit serum proteins was also identified in four sera, and was responsible for interference in the rabbit urinary protein RAST system.

Animals↗

PubMed2005

Effects of SDS, PBS solutions upon fluorescence values of Dermatophagoides pterronyssinus radioallergosorbent test inhibition.

OBJECTIVE: To explore the effects of SDS, PBS re-dissolvent solutions on fluorescence values of radioallergosorbent test (RAST) inhibition. METHODS: Dermatophagoides pterronyssinus allergen immunoCAP and UniCAP 100 System were used. The Sera Pool consisted of 20 Dermatophagoides pterronyssinus allergic patients sera, their specific IgE fluorescence values were between 12505 and 24776. RESULTS: Fluorescence value percentages decreased: 62.9%, 54.1%, 43.5%, 6.7%, 3.7%, 2.6%, 2.2%, and 1.4% respectively, when SDS concentrations were at 2%, 1%, 0.5%, 0.25%, 0.1%, 0.05%, 0.025%, and 0.01%. Fluorescence values decreased more than 5% with SDS concentrations equal to 0.25% or higher. PBS in 0.1 and 0.01 mol/L concentrations decreased fluorescence values 2.9% and 0.9% respectively. CONCLUSIONS: SDS is a commonly used surfactants in allergen extract and re-dissolvent prepared allergen precipitation for RAST inhibition. Thus effects of surfactants (e.g. SDS) upon the RAST inhibition tests must be considered when they were used as re-dissolvent agents to improve protein resolution in RAST inhibition.

Allergens↗

PubMed1984

Radioallergosorbent test (RAST) for measurement of IgG antibodies to Aspergillus fumigatus in sera of patients with different lung diseases.

A radioallergosorbent test (RAST) for measuring human anti-Aspergillus fumigatus (Af) antibodies of the IgG class is described. The use of 125I-labelled animal antibodies against human IgG is compared with the use of 125I-labelled protein A. Under optimal conditions the radioactivity binding ratio between pooled patients' serum and pooled healthy persons' serum is 8-11.5. The immunoblotting technique was used to investigate so-called non-specific binding. The results obtained show that most if not all human sera contain anti-Af antibodies of the IgG type. The difference between pathological and normal immunological response to Af antigens seems to be in the antibody titres rather than in the presence or absence of antibodies to these antigens.

Antibodies, Fungal↗

PubMed1986

[The application of multivariate analysis to the radioallergosorbent test (RAST)].

Multivariate statistical analyses using principal component analyses (PCA) and Mahalanobis' method were applied to the quality control of radioallergosorbent test (RAST). Mites and foods allergen were analyzed by PCA method, and foods allergen were analyzed by Mahalanobis' method. The vast differences in the distribution on titers among the mites and the foods were observed. To evaluate the results of a test and the quality of kits for test statistically, it should be better to use multivariate analyses such as PCA or Mahalanobis' method.

Allergens↗

PubMed1982

Development and use of three new radioallergosorbent tests in the diagnosis of penicillin allergy.

The synthesis and characterisation of three novel reagents for use in the radioallergosorbent test (RAST) for the diagnosis of penicillin allergy are described. The antigenic determinants involved are the benzyl penicillanyl, thiol-linked benzyl penicillenate and thiol-linked penicillamine. These reagents, and also one specific for the benzyl penicilloyl group, have been used to evaluate the sea of subjects suspected of suffering from penicillin allergy and to explore the aetiology of the respiratory dyspnoea experienced by some workers exposed to penicillin-containing dusts. The use of these reagents, while confirming the importance of the penicilloyl or major determinant of penicillin allergy, has shown that there is heterogeneity in the IgE response of penicillin-allergic patients and some patients have IgE antibody specific for one or more of the new determinants only. These reagents will, therefore, increase diagnostic capabilities. Their use has also confirmed that the disorder induced by occupational exposure to penicillins is not primarily mediated by IgE antibody specific for allergenic determinants represented by any of the available reagents.

Chemical Phenomena↗

PubMed1975

In vitro diagnosis of allergy. Radioallergosorbent test (RAST) studies with some allergens commonly encountered in Australia.

The radioallergosorbent test (RAST) is proving valuable for experimental work in allergy research and as an in-vitro supplement in the diagnosis of clinical allergy. A detailed description of the materials and procedures required to establish the technique as a routine laboratory method, and data obtained in setting up the method for use with a variety of allergens commonly encountered in Australia are presented.

Allergens↗

PubMed1981

An approach to fungal antigen relationships by radioallergosorbent test inhibition.

Antigenic relationships among three species of Aspergillus (A. fumigatus, A. glaucus, and A. flavus) were examined by paired cross-radioallergosorbent test (RAST) inhibition analysis, an in vitro technique based on human IgE antibody specificity. Alternaria tenuis was found to be antigenically unrelated to each of the three species of Aspergillus and was used as a negative control. A single test serum yielded uninhibited RAST indices of 6, 7.4, 8.1, and 7.8 for A. fumigatus, A. glaucus, A. flavus, and Alternaria tenuis, respectively. At a concentration of 10 mg/ml, A. fumigatus inhibited A. glaucus RAST by 63% and A. flavus RAST by 62%. A. glaucus inhibited A. fumigatus RAST by 36% and A. flavus RAST by 63%. A. flavus inhibited A. fumigatus RAST by 44% and A. glaucus RAST by 81%. Each species of Aspergillus produced significant but only partial inhibition of RAST to each of the other two species analyzed. Results indicate the existence of both shared and unique antigens among these three species of Aspergillus. Paired cross-RAST inhibition may be used as an approach to study species relationships among genera of several classes of clinically relevant fungi. Unless many strains are employed, data obtained do not represent a definitive analysis of species, because of possible different degrees of inhibition by various strains of a particular species. They do, however, allow for the antigenic comparison of two or more crude, poorly characterized preparations thought to be important in human allergic disease.

Antibodies↗

PubMed1975

Measurement of IgE antibodies by the radioallergosorbent test. I. Technical considerations in the performance of the test.

Since its introduction by Wide, Bennich, and Johansson in 1967, the radioallergosorbent test (RAST) has been increasingly used for measurement of specific IgE antibodies. In this study we have varied the conditions during the performance of the RAST and have investigated the effect of altering: (1) the speed of rotation of tubes, (2) the number of washes in both steps of the test, (3) the length of rotation of tubes, (4) the temperature, (5) the conditions during centrifugation, (6) the quantity of antibody to IgE in the second step of the test, (7) the composition of buffers in the reactions, (8) the type of tube employed in the test, (9) the quantity of antigen employed during the coupling procedure, and, finally, (10) the iodine isotope, 125I or 131I, used to radiolabel anti-IgE. Of these variables the most significant were the quantity of anti-IgE used in the second step of the test and the quantity of antigen used in the coupling procedure. Other variables of importance were the choice of radioiodine, whether the tubes were rotated or not, the type of tube used, and finally the diluent employed.

Allergens↗

PubMed1989

Clinical significance of molds newly available for radioallergosorbent testing.

Three years of weekly Rotorod airborne allergen reports from Corpus Christi, Texas, were reviewed. Five of 10 newly available airborne molds for radioallergosorbent testing (RAST) were present in significant numbers. Three hundred seventy-five mold RAST evaluations were expanded to include the five old and these five new molds. Except for Alternaria, the frequency of and allegenic response to the new molds were generally greater than those for the five old molds. The usual Alternaria-Cladosporium mold screen proved less satisfactory when these five new molds were added to the mold battery; however, the addition of Helminthosporium to the screen corrected this deficiency. Cross-reactivity production of false-positive responses seems unlikely because of frequent significant variance in RAST scores from mold to mold in the same patient.

Air Microbiology↗

PubMed1981

Comparison of the radioallergosorbent test and a quantitative solid-phase radioimmunoassay for the detection of ragweed-specific immunoglobulin E antibody in patients undergoing immunotherapy.

Commercially available radioallergosorbent test (RAST) was compared with a quantitative solid-phase polystyrene tube radioimmunoassay (PTRIA) for the detection of ragweed-specific IgE antibody in sera of patients undergoing ragweed immunotherapy. Both assays showed good replication over a wide range of IgE antibody activity. The RAST was limited in the ability to discriminate between sera with high levels of specific IgE antibody. In addition, RAST gave falsely low values of IgE antibody activity in the presence of high levels of blocking antibody.

Animals↗

PubMed1976

Iodinated versus fluorescent labelling in the radioallergosorbent test (RAST) for the determination of serum IgE levels.

Experiments were performed to determine the feasibility of replacing the radioactive 125I tag in the radioallergosorbent test (RAST) with a new fluorescent compound, 2-methoxy-2, 4-diphenyl-3 (2H)-furanone (MDPF). It was possible to discriminate a grass-allergic from a grass-non-allergic patient using the traditional RAST procedure with 125I-ant-IgE. However, when a fluorescent label, MDPF was attached to IgE using the same RAST procedure, it was not possible to discriminate between allergic and non-allergic responses. Additional experiments, using BSA and anti-BSA as a model, showed that it was possible to detect 0.025 ppm antigen using iodinated antiserum while the fluorescent tag had a lower limit of antigen detection of 0.20 ppm. It was possible to distinguish between allergic and non-allergic responses using 125I-N-succinimidyl-3(4-hydroxyphenyl) propionate (SHPP) which binds to protein in a manner similar to MDPF. These results suggested that the unsatisfactory fluorescence results were not due to an alteration of protein structure as a result of MDPF labelling. Although the fluorescence work was performed using a fluorimeter with optics and electronics optimized for detection of MDPF, sensitivity of the method was limited by high fluorescent background.

Allergens↗

PubMedDate not supplied

Comparison of an enzyme linked immunosorbent assay (ELISA) and a radioallergosorbent test (RAST) for detection of IgE antibodies to Brugia malayi.

The enzyme linked immunosorbent assay (ELISA) for specific IgE antibodies to Brugia malayi was compared with the radioallergosorbent test (RAST) for use in immunoepidemiological studies of lymphatic filariasis. Sera used were from individuals (aged 5-82 years) living in an area endemic for lymphatic filariasis in South Sulawesi, Indonesia. The percentage of positive IgE ELISA reactions (52.6%) among the population was lower than the percentage of positive RAST (94.5%). Although an overall significant concordance was found between the two assays (P < 0.001), 328 (42.7%) individuals with a positive RAST result were negative in the ELISA, whereas only 6 (0.8%) subjects were positive by ELISA, yet negative by RAST. When the population was divided into those with active infection (positive for anti-filarial IgG4) and those not infected (mf-negative and negative for anti-filarial IgG4), the correlation between the two tests was higher in the IgG4-positive (rho = 0.70) than in the IgG4-negative (rho = 0.52) group. These results indicate that in assessment of B. malayi specific IgE antibody, RAST is superior to ELISA. However, given the use of radioactivity in the RAST method and given our results obtained in subjects with high anti-filarial IgG4, one could consider using the IgE-ELISA in areas with high endemicity for filariasis. In areas with low endemicity or where control programs are implemented, sera will have to be tested by RAST.

Adolescent↗

PubMed1978

Reactivity of ragweed allergens with IgE antibodies. Analyses by leukocyte histamine release and the radioallergosorbent test and determination of cross-reactivity.

Five distinct proteins with allergenic activity have been isolated from short ragweed pollen. We initially tested three of these, AgE, AgK, and Ra3, for reactivity with IgE antibodies by leukocyte histamine release and by the radioallergosorbent test (RAST). We found highly significant correlations between the reactivities of these allergens by leukocyte histamine release and by the RAST, consistent with the view that both procedures detected comparable allergenic activity. We next tested the allergenic cross-reactivity of all five ragweed allergens. AgE, AgK, Ra3, Ra4, and Ra5, by RAST inhibition. With solid-phase AgE the only nonhomologous inhibitor was AgK, which cross-reacted weakly and required a 140-fold mass excess of AgK compared to AgE. With solid-phase AgK both AgK and AgE produced significant inhibition; AgE was slightly more potent than the homologous AgK, Ra3 and Ra5 were allergenically unique, because only the homologous allergen produced 50% inhibition. Ra4 was weakly inhibited by AgE, Ra3, and Ra5 when these allergens were added in 300- to 5---fold mass excesses; this weak inhibition may represent either cross-reaction or cross-contamination. We found that RAST inhibition could be used as an assay for the individual ragweed allergens and we demonstrated the presence of all of the allergens in a whole ragweed extract. The sensitivity of the RAST inhibition assay ranged from 10 ng to 100 ng for 50% inhibition. Finally, the solid-phase ragweed allergens were used to determine the frequency of elevated IgE antibody levels in 65 patients with ragweed hay fever. Virtually all of the patients reacted with AgE (97%), while 88% reacted with AgK, 51% reacted with Ra3, 28% reacted with Ra4, and 17% reacted with Ra5. These results highlight the usefulness of the RAST as a specific and sensitive tool for immunochemical studies of allergens.

Adolescent↗

PubMed1994

Timing of onset of allergic symptoms as a response to a double-blind, placebo-controlled food challenge in patients with food allergy combined with a radioallergosorbent test and the evaluation of proliferative lymphocyte responses.

The timing of onset of allergic symptoms in a double-blind, placebo-controlled food challenge (DBPCFC) was combined with a radioallergosorbent test (RAST) and evaluation of proliferative responses of peripheral blood mononuclear cells (PBMCs) in 27 atopic dermatitis patients with hen's egg allergy. Of the 27 patients, 11 showed reactions within 2 h (immediate group), and 16 showed reactions after more than 2 h (nonimmediate group) after ingestion of hen's egg. The RAST scores for hen's egg in the immediate group were significantly (p < 0.01) higher than those in the nonimmediate group, while the proliferative responses of PBMCs to ovalbumin in the nonimmediate group were significantly (p < 0.01) higher than those in the immediate group. These results suggest that the RAST values are related to immediate allergic symptoms in DBPCFC and the proliferative responses of PBMCs are related to nonimmediate allergic symptoms in DBPCFC. The timing of onset of allergic symptoms in DBPCFC will render DBPCFC more useful in the diagnosis of food allergy, including the late-onset reactions to foods.

Adolescent↗

PubMed1981

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.

Antibodies↗

PubMed1980

Interference in ragweed pollen and honeybee venom radioallergosorbent tests.

We studied sera from patients sensitive to short ragweed (SRW) and honeybee venom (HBV) to investigate serum factors able to interfere with the measurement of IgE antibody levels by the radioallergosorbent test (RAST). We heated sera to destroy IgE antibodies and tested them for interference in the RAST. Heating sera for 4 hr at 56 degrees C destroyed up to 98% of the IgE antibody activity. After immunotherapy sera from patients sensitive to SRW and HBV produced striking interference in the RAST. The interference was most marked in the RAST employing 50-microgram quantities of microcrystalline cellulose-linked allergens, but it was also evident in the RAST employing 500-microgram quantities of such allergens and in the commercial RAST in which allergen is linked to paper disks. The interfering substance eluted from diethylaminoethyl (DEAE) cellulose in the IgG fraction. The interference could be eliminated by increasing the relative quantity of solid-phase allergen; RAST interference was not detected when SRW extract was linked to Sepharose 4B. The results indicate that serum factors, presumably IgG antibodies, produce interference in the RAST. Thus immunotherapy studies that measure IgE antibody levels by the RAST must consider the possibility that IgG antibodies can appear to depress IgE antibody levels. Furthermore, because commercially available RAST disks are susceptible to RAST interference, they must be used with caution for the diagnosis of allergy in patients whose sera may contain significant quantities of IgG antibodies.

Animals↗

PubMed1983

Interference in the radioallergosorbent test by antibody light chains in rabbit urine.

Immunological techniques have been used to identify and quantitate rabbit antibody light chains in the urine of rabbits. The influence of these light chains on the radioallergosorbent test (RAST) used for the diagnosis of laboratory animal allergy to rabbit urinary protein allergens is described. The presence of IgG antibody specific for rabbit derived antigens in human serum has been confirmed.

Animals↗