Library

Notes: Until now, immunoassays for detection of anti-muscle relaxant IgE in serum have been performed with the drug coupled to epoxy-activated Sepharose or to RAST papers dics. In the present work we have used a quaternary ammonium-Sepharose in which the quaternary ammonium reactive group (choline chloride) was directly coupled to Sepharose via an ether linkage. 50 μl of the quaternary ammonium solid phase (QAS) was incubated with 50 μl of serum for 3 h, washed, incubated 18 h with 125I-anti-IgE and washed again. The results were expressed as the percentage of 125I-anti-IgE adsorbed onto the solid phase. The results were at 1.3±0.5% for 20 control sera, with an upper normal limit estimated to 2.3%. The within-run reproducibility ranged from 3.2% to 10.0%. The results were significantly correlated with those obtained with either alcuronium-epoxy-Sepharose, choline-epoxy-Sepharose, the RAST-alcuronium or with the RAST-succinyl choline (respectively, r - 0.66, r = 0.80, r = 0.81, r = 0.40 and r = 0.85). The values obtained with the sera of 83 patients ranged from 0.3 to 38.5%. The sensitivity was estimated at 87.9%, 66.7% and 40.7% with the QAS-RIA, the RAST-succinyl choline and the RAST-alcuronium, respectively. The inhibition of adsorption of specific IgE onto the gel ranged from 13.0 to 90.6% in presence of 130 nmol of soluble muscle relaxants. In 83.3% of 30 cases, the highest inhibition was obtained with the muscle relaxant which was clinically incriminated. In conclusion, the reactive-solid phase which was used in the present work significantly increased the sensitivity of detection of anti-muscle relaxant IgE in serum.

Notes: We have evaluated the in vitro leukocyte histamine release tests for the diagnosis of allergy to muscle relaxant drugs in 40 patients (Group A) and a control group of 44 subjects with negative leukocyte histamine release (Group B). Non-IgE dependent histamine release, expressed as a percentage of the total blood histamine, was 3.94%± 0.49 in Group B. The upper limit of positivity was estimated to be 5% (mean + 2 SD). Leukocyte histamine release tests were positive in 65 % of the patients from Group A. The concordance between LHR and QAS-RIA was 64%. The maximal histamine release was observed at dilutions of 10−2–10−4 in 20 of the 26 positive cases. The maximal histamine release was 43.8%± 23.3. The spontaneous histamine release was as low as 1.7%± 1.1. Cross-reactivity among the 5 different muscle relaxant drugs has been investigated and compared by intradermal testing. The muscle relaxant drugs which gave the lower skin reaction (M2) and the drug responsible for shock (M1) were selected for the study of in vitro leukocyte histamine release. Of 20 patients, 10 had, simultaneously, a positive test to Ml and a negative to M2. All of the 10 cases had negative ID tests with M2. Three of these patients subsequently underwent general anesthesia with the muscle relaxant chosen as harmless (M2) without any clinical reaction.

Notes: The diagnosis of food IgE-dependent hypersensitivity is based on the demonstration of specific IgE, completed by provocation tests. Two immunoenzymatic techniques, the Phadezym and the FAST, are compared with the Phadebas RAST, in 86 sera (23 controls, 28 from patients with a reported food allergy and 35 with a positive RAST to a food allergen). The within-run variation coefficient of class 0–2 sera was 9% for the Phadebas RAST, and higher than 20 % for the Phadezym and the FAST. It was in order of 8.7%, 9.4% and of 17.6% 〉 respectively for Phadebas RAST, Phadezym and FAST when estimated with class 3–4 sera. The specificity was higher than 95 % for the three techniques. The sensitivity was 75% for Phadebas and 43% for Phadezym and FAST. The FAST test is much less sensitive with allergens of vegetal origin than those of animal origin (P 〈 0.01). This work indicates the high percentage of false negative results of immunoenzymatic techniques when food extracts are tested. This could be explained either by an enzyme-substrate reaction or by a non-specific inhibition of the enzyme linked to the anti-IgE IgG.

Notes: The specific IgE levels for 11 allergens were compared in 288 patients by means of the Phadebas RAST and the IgE-FAST. Agreement (〈 1 class difference) was observed in 78.7% of the cases. The best agreement was observed with Phleum pratense, egg white, corn, Betula verrucosa and cat epithelium. In 91 cases the results were retrospectively compared with clinical data and skin tests. When RAST and FAST differed (n= 31) 93.5% and 51.6% of the respective results were in agreement with the skin test. When RAST and FAST were similar (n= 60) 81.7% and 80.0% of the respective results were in agreement with the skin test. It was concluded that the RAST and the FAST gave similar results in most cases but that the RAST was more sensitive than the FAST, especially when the results obtained with both methods differed.

Notes: 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 ≈34 kDa, ≈50 kDa and ≈ 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.

Notes: Anaphylactic shock is an immunoglobulin E (IgE)-dependent hypersensitivity. Biological tests like leucocyte histamine release (LHR) and human basophil activation (HBA), frequently used in human allergy, reflect both the amount of IgE fixed on cells and the cellular reactivity. To assess whether serum-specific IgE from Brown Norway (BN) rats prepared for ovalbumin (OVA)-induced anaphylactic shocks can activate human basophils which has a potential interest in experimental allergy: such a test could rapidly assert an IgE sensitization in laboratory animals genetically T-helper 2 (Th2)-predisposed. Rats (n = 39) were immunized three times (day 0, day 5 and day 21) with OVA injected subcutaneously. One week after the third immunization, a shock was induced with an intravenous (i.v.) bolus of OVA. Sensitization was assessed by passive cutaneous anaphylaxis (PCA) test and dosages of serum IgE antibodies anti-OVA by enzyme-linked immunosorbent assay. Blood basophils were counted before and during the shock. Before the shock induction (at day 21), an LHR test was performed on rat blood, and human basophils were sensitized with rat sera. HBA was demonstrated by the increase in the percentage of cells expressing CD63 antigen membrane, measured by flow cytometry. Twenty-one days after the first subcutaneous (s.c.) immunization, the rat serum induced a significant HBA. HBA was observed neither with the same serum previously heated nor with the serum from nonimmunized rats (NIRs). OVA-specific IgEs were significantly increased in immunized rat (IR) serum. The PCA test was negative when the serum was previously heated (56 °C). We never observed any circulating basophils, and LHR test was negative. After OVA i.v. administration, all IRs died rapidly. HBA testing strongly suggests a mediation by specific IgE in the increase of CD63 in BN rats. Thus, HBA test seems useful in assessing whether an experimental allergy was induced in animals genetically predisposed to an immune response, Th2-mediated, like BN rat. We also conclude that rat basophil activation does not participate in the histamine release during anaphylactic shock in sensitized BN rats.

Notes: Histamine plays a key role in the pathogenesis of chronic urticaria (CU). The authors of this paper have studied the effects of ingested histamine in 25 patients with CU. A 120 ing dose of histamine. well-tolerated in the healthy subject, was instillated into the duodenum. Concomitantly. plasma histamine (H) levels and plasma and urinary methylhistamine (MH) levels were measured. Intraduodenal administration of histamine was responsible for the development of an attack of urticaria in 64% of patients, while control subjects were asymptomatic. Plasma histamine levels were significantly higher after digestive histamine challenge (DHC) in patients with CU compared with controls. An abnormal increase in plasma histamine was observed in 72% of them. Plasma MH exhibited the same kinetic behaviour with a usually delayed time-pattern. Urinary MH concentration was higher in patients presenting with early-onset urticaria during the first hour than in those with the late-onset type between 1 and 12 hr after DHC. The coefficient of mcthylation (plasma MH/MH + H) was not significantly different in patients presenting with an attack of urticaria following DHC and in other subjects, Urinary excretion of MH and urinary flow increased significantly in patients presenting with an attack of urticaria following DHC which corresponds to increased absorption of histamine during the 5-hr period following DHC and its role on excretion by the kidney via vasodilation which it induces. This study demonstrates the abnormal frequency of disturbances in the metabolism of exogenous histamine in patients with CU. Increased plasma H accounts for the abnormal passage of H across the intestinal barrier which can result either from intestinal hyperpermeability and/or a deficit in the enzymatic catabolism of histamine. The systems of methylation and urinary clearance of MH appear to be effective. It is thus postulated that there is a deficit in diamine oxidase (DAO) in the enterocyte. The lack of correlation between the kinetic behaviour of plasma H and the onset of urticaria draws attention to the extent of individual variability in skin reactivity to histamine.

Notes: Background After penicillins, cephalosporins are the betalactams that most often induce IgE-mediated reactions. The development of diagnostic tests has been delayed, however, because the cephalosporin allergenic determinants have not been properly identified.Objective To evaluate the usefulness of skin tests, serum specific IgE assays, and challenges in diagnosing immediate reactions to cephalosporins and to clarify the pathogenic mechanism of such reactions.Methods We studied 76 adults with immediate reactions to cephalosporins, mainly ceftriaxone, cefotaxime, and ceftazidime. Skin tests and serum specific IgE assays were performed for culprit cephalosporins and cefaclor, as well as for penicillin, amoxicillin, and ampicillin. Some subjects with negative results underwent challenges and re-evaluations. Responses to cephalosporins other than the culprit ones were also studied.Results In the first allergologic work-up, an IgE-mediated hypersensitivity to penicillins and/or cephalosporins was diagnosed in 63 (82.9%) of the 76 patients on the basis of skin-test and/or specific IgE assay positivity. Of the 13 negative patients, eight accepted challenges and underwent re-evaluations. Considering both first- and second-evaluation results, the skin-test-positivity rate increased from 76.3% to 85.5% and that of sepharose-radioimmunoassay positivity from 67.1% to 74.3%. Overall, an IgE-mediated hypersensitivity was diagnosed in 70 patients (in seven after retesting). On the basis of skin-test and CAP-FEIA results, we classified our 76 patients into five groups: group A (three patients), positive only to penicillin reagents; B (17), positive to both cephalosporin and penicillin reagents; C (24), positive to more than one cephalosporin; D (21), positive only to the responsible cephalosporin; E (11) negative to skin tests and CAP-FEIA, including five sepharose-radioimmunoassay positive.Conclusions Most immediate reactions to cephalosporins appear to be IgE-mediated. Cephalosporin skin testing and sepharose-radioimmunoassay are useful tools for evaluating these reactions. Cephalosporin IgE-mediated hypersensitivity may be a transient condition; therefore, allergologic exams should be repeated in patients with negative initial allergologic work-ups, including challenges.