Performance of a component-based allergen-microarray in the diagnosis of cow's milk and hen's egg allergy.

BACKGROUND: The food challenge test (FCT) is the gold standard for the diagnosis of food allergy. This procedure is time consuming, costly and can induce potentially severe symptoms. An ideal in vitro test should allow to avoid the FCT. Objective To assess the clinical performance of microarray for specific IgE (sIgE) detection in children with challenge-proven/excluded cow's milk (CM) or hen's egg (HE) allergy. METHODS: One-hundred and four children with suspected IgE-mediated hypersensitivity to CM or HE were studied. In all patients, skin prick test, ImmunoCAP, microarray and FCT were performed. RESULTS: The microarray components Bos d 8 for CM (27/58 patients) and Gal d 1 (20/46 patients) and Gal d 2 (24/46) for HE were the most frequently recognized allergens. Using the FCT results as the reference parameter, sIgE to Bos d 8 and Gal d 1 had the highest area under the curves. These were not significantly different from those obtained using the ImmunoCAP. Use of 95% clinical decision points (CDP) for sIgE to Bos d 8 and Gal d 1 resulted in higher negative predictive values (78% and 79%, respectively) than those obtained with the ImmunoCAP (57% and 59%). CONCLUSIONS: Our results show that in children with suspected CM or HE allergy, the microarray has a good ability to predict the FCT results. In a clinical application perspective, the microarray could be used as a second-level assay, if the ImmunoCAP sIgE is <95% CDP. This approach would lead to a decrease in the number of the FCT to be performed, as well as of positive FCTs with a subsequent decrease in severe reaction risk.

Prevalence of sensitization to Cupressus sempervirens: a 4-year retrospective study.

In the last few years Cupressus sempervirens has been identified as the cause of an increasing number of cases of late winter-early spring pollinosis in Mediterranean countries. We conducted a 4-year retrospective study of a large group of subjects with documented allergic respiratory disease in order to determine the prevalence, clinical significance and annual rate of sensitization to C. sempervirens pollen. Anamnestic data and skin prick tests (SPT) with common aeroallergens and C. sempervirens extract were collected from 1397 subjects (712 male and 685 female) resident in Latium, a region in central Italy, with complaints related to upper- or lower-respiratory-tract disorders or conjunctival disease. Two hundred and forty-three subjects (17.4%) showed positive results to C. sempervirens extract: 47 (19.3%) of them were monosensitized. The annual sensitization rate of SPT positivity to C. sempervirens varied from 7.2% in 1995 to 22% in 1998. All the subjects monosensitized to cypress pollen had symptoms from January through April. Our study suggests that sensitivity to C. sempervirens is responsible for respiratory symptoms in an increasing percentage of subjects. Further studies are needed to determine its frequency at the national level.

The 18 kDa peanut oleosin is a candidate allergen for IgE-mediated reactions to peanuts.

BACKGROUND: Peanut allergy is one of the five most frequent food allergies in children and in adults. Recently, we purified and evaluated the allergenicity of peanut oleosins, a family of small-sized proteins involved in the formation of peanut oil bodies. METHODS: Allergenicity of the purified native protein and of the recombinant protein was tested by Western blot and by IgE-RIA. RESULTS: We found IgE-binding with oleosin in 3 of 14 sera of patients who had suffered an allergic reaction to peanuts. Two sera reacted weakly against 16-18 kDa proteins corresponding to oleosin monomers, in Western blot. The main reacting bands had a molecular size estimated at approximately 34 kDa, approximately 50 kDa and approximately 68 kDa and could therefore correspond to oleosin oligomers. IgE reactivity was higher in extracts from roasted peanuts. The same phenomenon occurred with crude soybean oil fraction, with two bands of 16.5 and 24 kDa corresponding to monomers, and two bands of 50 kDa and 76 kDa corresponding to dimers and trimers, respectively. The 18 kDa band was observed in the 3 Western blots of a membrane-enriched fraction of recombinant oleosin produced in the Sf9-baculovirus expression system (performed with the 3 patient sera). CONCLUSIONS: We have characterized a new peanut allergen which belongs to the oleosins, a family of proteins involved in the formation of oil bodies. The protein may be involved in some of the allergic cross-reactions to peanuts and soybeans.

Delayed hypersensitivity to diclofenac: a report on two cases.

BACKGROUND: Although skin reactions have been reported during use of diclofenac, a nonsteroidal anti-inflammatory drug, immunopathogenic mechanisms have been demonstrated in only a few cases. METHODS: We administered skin and patch tests to two subjects who had developed maculopapular rashes respectively 48 and 72 hours after initiation of treatment with diclofenac. RESULTS: In both cases, prick and intradermal tests with the drug were negative at 20 minutes, but 24 hours later an erythematous infiltrate had appeared at the intradermal test site. Patch tests with diclofenac were also positive at 48 and 72 hours. CONCLUSIONS: The features of both these cases are suggestive of delayed hypersensitivity to diclofenac. Delayed-reading intradermal and patch tests may be a simple and effective means of diagnosing reactions of this type.

Food-dependent exercise-induced anaphylaxis: clinical and laboratory findings in 54 subjects.

BACKGROUND: In some subjects, specific foods trigger anaphylaxis when exercise follows ingestion (specific food-dependent exercise-induced anaphylaxis, FDEIAn). Skin test and/or RAST positivity to foods suggest an IgE-mediated pathogenic mechanism. Others suffer from anaphylaxis after all meals followed by exercise, regardless of the food eaten (nonspecific FDEIAn). We sought to identify the culprit foods with a diagnostic protocol. METHODS: We collected detailed histories and performed skin prick tests (SPT) with 26 commercial food allergens, prick plus prick tests (P+P) with 15 fresh foods (including 9 assessed with SPT), and RAST for 31 food allergens. Treadmill stress tests were administered after a meal without any positive food (food plus exercise challenge, FEC). RESULTS: Among the 54 patients, 6 could not recall any suspect food. The other 48 suspected a specific food in at least one episode. The most frequent were tomatoes, cereals and peanuts. Fifty-two subjects were positive to at least one food (22 to more than 20), whereas 2 showed no positive results. All suspect foods were positive. SPT, P+P and RAST displayed different degrees of sensitivity. Each test disclosed some positivities not discovered by others. Two subjects reacted to FEC. Overall, 48 patients probably had specific FDEIAn and the other 6 nonspecific FDEIAn. CONCLUSION: It is useful to test both in vivo and in vitro an extensive panel of foods. Avoidance of foods associated with skin test and/or RAST positivity for at least 4 h before exercise has prevented further episodes in all our patients with specific FDEIAn.

Immediate allergic reactions to cephalosporins: cross-reactivity and selective responses.

BACKGROUND: After penicillins, cephalosporins are the most important beta-lactams inducing IgE-mediated reactions. Responses may be selective or cross-reactive with common beta-lactam determinants. Unlike determinants derived from benzylpenicillin, cephalosporin allergenic determinants have not been properly identified, even though a wide variety of these beta-lactams is currently used. OBJECTIVE: We sought to evaluate the IgE response in subjects with immediate allergic reactions to injectable cephalosporins and to assess their reactivity to different penicillins and cephalosporins. METHODS: We studied 30 subjects with immediate reactions to one or more of the following cephalosporins: ceftriaxone, cefotaxime, ceftazidime, and cefuroxime. Skin tests and in vitro-specific IgE antibody assays were performed for major and minor determinants of penicillin G, amoxicillin, and ampicillin, as well as for the culprit cephalosporins. Responses to cephalosporins other than the culprit ones were also studied by using skin testing. RESULTS: Twenty-six patients (group A, 86.7%) displayed skin test and RAST negativity to penicillin determinants and skin test positivity to cephalosporins, with RAST confirmation in 9 patients. Four subjects (group B, 13.3%) had a positive response to penicillin determinants. In group A two patterns of reactivity were observed: one characterized by a response only to the culprit cephalosporin (n = 15, 57.7%) and the other by positive responses to different cephalosporins, including the responsible cephalosporins (n = 11, 42. 3%). CONCLUSION: Most patients with a history of immediate reactions to cephalosporins are sensitized to determinants generated only by cephalosporins (group A), although a small percentage react to penicillin determinants (group B). Some patients from group A responded only to the culprit cephalosporin, but others reacted to different cephalosporins. These findings can be explained in terms of either selective response to unique determinants or cross-reactivity.