IgE antibodies to house dust, mite, animal allergens and moulds in house dust hypersensitivity

Comparison of two assays for the determination of specific IgE in serum of atopic and nonatopic subjects: the Allergenetics FAST and the Phadezym RAST

The FAST assay (Allergenetics) for the determination of specific IgE has recently been introduced. The results of this test, graded in classes 0 (negative), 1 (equivocal) and 2 to 6 (positive) were compared with those of another commercially available test (Phadezym RAST, Pharmacia), graded from class 0 (negative) and classes 1 to 4 (positive). In 52 adults suffering from rhinitis/asthma, a total of 114 positive skin prick tests (SPT) were obtained for common respiratory allergens. In 67% of these tests the Phadezym RAST was positive and in 63% the FAST was positive (classes 2 to 6). In these patients there were 151 negative SPT: 6% corresponded to a positive Phadezym RAST (all class 1) and 34% to a positive FAST (classes 2 to 6). The serum of nine nonatopic volunteers who had negative SPT for 12 common allergens were tested. In none did the Phadezym RAST give any positive results; the FAST was positive in all nine sera, detecting between five and 11 allergens. When both assays were performed on 14 unselected cord blood samples, the Phadezym RAST was positive in three samples (with class 1 results to a maximum of two allergens), and the FAST was positive in 12 samples, detecting between one and seven allergens. Thus, in our hands, the FAST gave an abnormally high number of positive results in patients with negative SPT, in nonatopic volunteers, and in cord blood.

Improvement of the radioallergosorbent test (RAST) sensitivity by using an antibody specific for the determinant D epsilon 2

A technical modification was introduced by the manufacturer (Pharmacia) of a commercially available RAST, with the use of an anti-IgE antibody specific for the domain epsilon 2 of the IgE molecule. Results of the previous and of the new RAST were compared in 100 patients suffering from bronchial asthma or chronic rhinitis. When the same serum was assayed by both techniques, the new RAST technique disclosed a higher positivity in 26% of the comparisons. The new RAST improved the overall correlation between RAST and skin-tests by 6%: individually by 12% for house dust, 8% for Dermatophagoides pteronyssinus and 15% for animal danders. However, the level of correlation was decreased by 8% for the moulds. In patients with a total IgE concentration larger than 100 PRIST units, the new RAST allowed the demonstration of specific IgE in a number of cases twice as large as the previous technique. Thus, the modification of the RAST provides a more sensitive test, the results of which better correlate with those of other diagnostic methods.

Controlled trial of an electrostatic precipitator in childhood asthma

A cross-over trial was conducted on 10 children with moderate to severe asthma, who had positive skin tests to Dermatophagoides pteronyssinus and nocturnal wheeze. An electrostatic precipitator was used during the night to remove airborne particles from the bedroom. During use of the precipitator peak expiratory flow rates were no better than in a control period.

Inhibition experiments with solid phase mite or epithelia in house dust hypersensitivity

The present study was undertaken to verify that mites are not the only allergens in house dust extracts and that other allergens such as cat epithelia can also be responsible for house dust hypersensitivities detected both by house dust skin tests and house dust RAST studies. In order to determine whether mite or epithelia fixed on a solid phase could remove not only the IgE antibodies reactive with the homologous allergens, but also the IgE antibodies reactive with house dust allergens, the authors have absorbed 10 sera of house dust allergic patients with solid phase mite or epithelia. The absorption procedure removed a large part of the IgE antibodies reactive with specific immunosorbent (Dermatophagoides pteronyssinus or cat epithelia) and in the same way the IgE antibodies reactive with house dust immunosorbent. The percentage of RAST inhibition varied from 65% to 92% for Dermatophagoides pteronyssinus and from 65% to 94% for house dust in patients allergic to house dust and mite; the percentage of RAST inhibition varied from 67% to 92% for cat epithelia and from 73% to 90% for house dust in patients allergic to house dust and cat epithelia. This is in accordance with the hypothesis that house dust is not an allergen per se, but rather a complex mosaic of several allergens including mite, animal epithelia, etc.

Comparison between ketotifen and DSCG in bronchial challenge

A double-blind cross-over study showed that orally taken ketotifen and inhaled DSCG have a comparable protective effect on allergen-induced bronchoconstriction. Both drugs significantly inhibit the immediate bronchial reaction after a 3 day treatment with either 1 mg ketotifen or 20 mg DSCG four times daily. Late reactions, which occurred in three out of the ten patients, were inhibited in two of the three patients by ketotifen as by DSCG.

Specific IgE estimations by RAST in Japanese asthmatics compared with skin, passive transfer and bronchial provocation tests

198 asthmatics and twenty healthy persons were studied by RAST and in vivo tests with four common inhalant allergens. (a) Higher RAST classes were elicited with mite (Dermatophagoides farinae) extract and lower classes with other allergens. The agreement between positive RAST and skin or P-K tests was highest with the mite extract. RAST sensitivity was dependent on the kinds of allergens and was most sensitive to mite extract. Positive RAST was most closely related to the prick test reactions. (b) RASTs to house dust and mite extract were examined in terms of the threshold dosage of house dust and also the types of bronchial response (early, dual and late) induced by a certain amount of house dust; higher RAST classes were found in subjects with bronchial response to the dual or early type, elicited by a threshold dosage of diluted extract, while lower RAST classes were found in cases of the late-type response elicited by the threshold dosage of concentrated extract. (c) Changes in IgE antibodies to house dust and mite extract were estimated in patients with positive house dust provocation. A greater increase occurred in cases of dual or early response, a smaller increase in those with a late response. Despite discordances in skin tests and RAST between house dust and mite extracts, the increases in IgE antibodies to mite extracts as well as house dust were observed in all cases, presumably caused by an allergenic identity between the allergens.

Correlation between skin tests, inhalation tests and specific IgE in a study of 120 subjects allergic to house dust and Dermatophagoïdes pteronyssinus

The radioallergosorbent test was compared with currently accepted allergy diagnostic techniques in seventy-four controls and 120 patients with a clinical history of allergy to house dust and Dermatophagoïdes pteronyssinus. The results obtained with D. pteronyssinus allergen extract show a close correlation between the size of the cutaneous reactions and the serum level of allegen-specific IgE. On the other hand, highly positive skin tests to house dust were not always correlated with a positive RAST response for house dust. Similar results were found with inhalation tests. When a purified D. pteronyssinus extract was used, a stronger relationship was observed between RAST, cutaneous and inhalation tests. It can be assumed that RAST for house dust is not of value in patients with house dust and mite allergy. Our findings indicate that the correlations between RAST results and other in vivo test results depend on the purity of the allergen extracts and the selection of patients.