Negative Challenge Test Research Articles

Dalhousie dyspnea scales: Pictorial scales to measure dyspnea during induced bronchoconstriction

The aim of this study was to validate our Dalhousie Dyspnea Scales in children referred for histamine bronchoprovocation challenge. Seventy-four children rated their dyspnea after each FEV(1) measurement following inhalation of doubling histamine concentrations from 0.125 to 8.0 mg/ml by the standard tidal breathing method. Serial FEV(1) and dyspnea rating using the Dalhousie Dyspnea Scales were recorded and Kendall's tau was computed for dyspnea rating versus fall in FEV(1). Subjects were split into those with positive (DeltaFEV(1) >or= 20% with PC(20) <or= 8 mg/ml) or negative histamine challenge test. During histamine inhalation, dyspnea ratings on each of the subscales rose as FEV(1) fell across subjects, whether or not they were histamine-responsive (main effect), and then fell dramatically following relief of induced obstruction by bronchodilator.The Dalhousie Dyspnea Scales are useful and accurate tools to measure dyspnea due to bronchoconstriction in children.

Síndrome de Hoigne

Background Hoigne's syndrome is a pseudoanaphylactic or pseudoallergic reaction that occurs after intramuscular administration of penicillin G procaine or benzathine. These are usually embolic toxic reactions possibly due to vascular occlusion by large crystals of the penicillin salts. We report a case of Hoigne's syndrome. Case report A 44-year-old woman received 1,200,000 U.I. of intramuscular procaine penicillin once daily for treatment of acute amygdalitis. Immediately after the second dose the patient developed mental confusion, visual and auditory hallucinations, perceived changes of body shape, swelling of the tongue and a fear of impending death. Penicillin allergy study (serum-specific IgE levels, skin tests and provocation test) was performed. The diagnosis of Hoigne's syndrome was confirmed by negative oral challenge test with penicillin. Conclusions Hoigne's syndrome is a pseudoanaphylactic reaction that must be differentiated from authentic anaphylactic shock due to penicillin. This distinction allows treatment to be continued in Hoigne's syndrome, whereas it is contraindicated in anaphylactic shock.

IgE binding to pepsin-digested water soluble and insoluble wheat proteins.

Positive skin prick tests to wheat are a common finding among atopic patients, but only a minor fraction of these patients show immediate clinical symptoms after wheat ingestion. The aim of this study was to evaluate the allergenicity of wheat proteins after pepsin treatments. Six patients with positive specific IgE and/or skin prick test to soluble wheat proteins and to gluten were studied. Five of them had no symptoms after wheat ingestion and showed a negative oral challenge test. All sera were analysed with extracts obtained after pepsin hydrolysis during different time periods of water-soluble and insoluble wheat proteins by IgE immunoblotting. A pepsin-sensitive allergen of around 35 kDa was recognized by the five atopic negative wheat oral challenge patients in the undigested water-insoluble extract. A patient showing immediate urticaria after wheat ingestion detected a pepsin-resistant allergen with similar molecular weight. Finally, an inhalation-induced asthma patient recognized water-soluble proteins (of around 14 kDa) that could correspond to the alpha-amylase inhibitors. Our immunoblotting method shows better correlation with the clinical symptoms than skin prick test and CAP results. Pepsin resistance of the acetic acid-soluble wheat proteins may be responsible for the immediate symptoms of the patient who presented immediate urticaria.

Is this patient allergic to penicillin? An evidence-based analysis of the likelihood of penicillin allergy

Salkind AR, Cuddy PG, Foxworth JW (University of Missouri–Kansas City School of Medicine, Kansas City, MO) Antibiotics containing penicillin may be withheld from patients based on their self-reported history of an adverse reaction to penicillin. From 0.7% to 10% of the general population suffers some kind of adverse reaction to penicillin, with the severity depending on exposure history, route of administration, duration of treatment, time elapsed from reaction to diagnostic skin testing or repeat exposure, and type of initial reaction. Type I or immediate reactions show systemic manifestations of anaphylaxis and occur in 0.004% to 0.15% of penicillin courses, most often in adults aged 20 to 49 years. In these reactions, penicillin or its reactive metabolites bind covalently to serum proteins and cross-link with preformed penicillin-specific immunoglobulin E antibodies in mast cells or basophils. With cross-linking to allergen, mast cells release their mediators. Late reactions occur after 72 hours of drug administration and are termed types II, III, or IV. Skin testing reveals possible cross-reactivity in individuals with previous type I reactions, but this is less likely with the nonimmediate reactions. Unless rash develops, a serious reaction is unlikely, so penicillin can be given; other causes of rashes, such as viral or bacterial infections or other medications, must be ruled out. A cross-reactivity between cephalosporins and penicillins may occur, but most patients with penicillin allergy tolerate cephalosporins without significant reaction. Allergic reactions occurred within 24 hours of cephalosporin administration in 5.6% of patients with a penicillin allergy history and a positive skin test result and in 1.7% of patients with a penicillin allergy history and a negative skin test result. Based on 4 studies, the presence of a clinical history indicative of penicillin allergy increases the chance that skin testing will be positive, but the absence of such a history only decreases the likelihood of a positive skin test result by just over half. Patients with no clinical history of a type I penicillin reaction do not need to undergo a penicillin skin test, although elective testing has been suggested. An oral penicillin challenge may be administered to patients with positive penicillin allergy histories and negative skin tests; generally these patients will have a negative oral challenge test result and can receive penicillin. For patients with a history of penicillin allergy who require a cephalosporin, the likelihood that it was a type I reaction should be determined. If the history indicates that it is not a true penicillin allergy, the cephalosporin can be administered. Penicillin skin testing is indicated for a concerning history, with the cephalosporin given with a negative test and cephalosporin desensitization considered for a positive test if no other medication is feasible. Carbapenems should not be used for patients with a positive penicillin skin test or a concerning history of a type I allergic response to penicillin, but aztreonam is usually safe for use in these patients. Patients who have a negative response to the oral challenge test can safely receive penicillin in 98% of cases. Salkind and colleagues provide a nice review of penicillin allergy and how to approach patients who claim to have a penicillin allergy and require antibiotic therapy. The bottom line is that most patients reporting a history of penicillin allergy are not truly allergic.

Prospect for vaginal delivery of growth restricted fetuses with abnormal umbilical artery blood flow.

The best mode of delivery in cases of intrauterine growth restriction (IUGR) with umbilical artery blood flow changes is not well elucidated. To evaluate outcome in IUGR with umbilical artery blood flow changes planned for vaginal delivery after a negative oxytocin challenge test (OCT). In 84 term singleton pregnancies with suspected IUGR and no unanimous indication for abdominal delivery, Doppler velocimetry and OCT were performed. Positive OCT cases were delivered by cesarean section, negative OCT cases planned for vaginal delivery. Umbilical artery Doppler velocimetry was normal in 51 cases (normal group) and abnormal in 33 cases (increased pulsatility index with maintained forward diastolic flow). Gestational age at delivery was shorter (p = 0.008), positive OCT more common (33% vs. 16%; p = 0.06), and vaginal delivery less common (40% vs. 63%; p = 0.04) in the abnormal blood flow group compared with the normal flow group. When in labor, 68% in the abnormal flow group and 76% in the normal flow group delivered vaginally (p = 0.6). One baby had a lethal malformation and another suffered meconium aspiration and pneumothorax, but was discharged home healthy. The vaginal delivery rate was significantly lower in the abnormal flow group compared with the normal flow group, but in cases finally destined for a trial of labor the vaginal delivery rates were similar. There was no indication that any fetus was exposed to detrimental hypoxia or distress.

Immune Tolerance to Drugs. I. Long‐Term Tolerability of Rokitamycin in Patients with Antibiotics Hypersensitivity

Macrolides are considered one of the safest anti‐infective groups in clinical use and are well‐tolerated as alternative antibiotics in patients with a previous adverse reaction to other classes of antibiotics. However there is scarce information in the literature about their long‐term tolerability. The present study was performed to determine whether the results of a challenge test with rokitamycin could predict the response to ingestion of rokitamycin during illness. The study was carried out on 335 patients, who experienced adverse reactions to one or more antibiotics. All patients received peroral challenges with rokitamycin (granules or capsules). On the first day patients received a number of placebo doses equivalent to the rokitamycin doses. One week later, the test was administered by increasing doses of rokitamycin at 60 min intervals until the common daily therapeutic dose of 406.25 mg was reached (31.25–93.75–125–156.25 mg). A questionnaire was distributed to all subjects. In particular, subjects were asked to clarify any reactive symptom they had developed after ingestion of the drug. It was found that only 3.1% (4/129) of subjects, who used this drug, reported adverse reactions: three experienced urticaria/angioedema and one patient experienced erythema multiforme during treatment. This study, points out a low percentage of adverse reactions to rokitamycin after a negative challenge test, thus, emphasizing both safety and good predictive value as a challenge test.

Value of a Negative Aeroallergen Skin-Prick Test Result in the Diagnosis of Asthma in Young Adults: Correlative Study With Methacholine Challenge Testing

None of the existing tests for the diagnosis of asthma are considered to be definitive. Certain circumstances require prompt diagnosis, and a test able to predict the absence of asthma would be very useful. To evaluate the contribution of a skin-prick test (SPT) to the diagnostic workup of subjects with suspected asthma. The study included three groups of subjects aged 18 to 24 years: group A, asthmatic patients (n = 175); group B, control subjects (n = 100); and group C, subjects with suspected asthma (n = 150) with normal spirometry findings and a negative exercise challenge test result. All underwent an SPT to a battery of common aeroallergens, and group C underwent a methacholine challenge test (MCT) in addition. The sensitivity, specificity, positive predictive value, and negative predictive values (NPV) of the SPT were calculated using provocative concentrations of methacholine causing a 20% fall in FEV(1) (PC(20)) of < 4 mg/mL and < 8 mg/mL as diagnostic cutoff values for asthma in the MCT. Bayes' formula was used to determine posttest probabilities of having asthma, both for positive and negative SPT results. A positive SPT result to at least one allergen was found in 95.5%, 54%, and 69% of patients in the three groups, respectively. The sensitivity, specificity, and NPV of the SPT were 90.7%, 52.0%, and 84.8%, respectively, with a cutoff value of PC(20) < 8 mg/mL. The lower cutoff, PC(20) < 4 mg/mL, increased the sensitivity and NPV to 98.2% and 97.8%, respectively. A negative SPT result decreased the probability of having asthma by 10-fold to 20-fold in subjects whose pretest probability was low to moderate. Incorporating an SPT into the workup of subjects with suspected asthma can reduce the cost of this process significantly. The SPT may be used as a simple, fast, safe, inexpensive, and reliable method to predict the absence of asthma in young adults.

Marginal seal of sealant and compomer materials with and without enameloplasty

Although true allergic reactions to local anaesthetics are rare in the general population, the importance of the problem among asthmatic children has yet to be documented.Skin prick, intradermal and incremental challenge tests with lidocain were performed in 157 asthmatic children aged 8-15 years and compared with 72 nonasthmatic children of a similar age. All of the asthmatic subjects were allergic to at least one allergen, most frequently pollens and house dust mites. Prick testing began with an undiluted solution in patients without a history of allergy and with 1:100 dilution in those with a reaction history. Following negative prick testing, intradermal or incremental challenge tests were performed.A total of 125 patients (80%) had been given local anaesthetics in the past, only three children gave history of an adverse local reaction. At the end of the tests, none of the subjects including controls, were found to have immediate or delayed-type allergy to lidocain.Local anaesthetic allergy does not seem to be a serious problem among asthmatic children and testing in all asthmatic children is not warranted. Those with an adverse reaction history to local anaesthetics should be tested with these drugs.

Sensitivity to local anaesthetics among asthmatic children

Summary.Objectives.Although true allergic reactions to local anaesthetics are rare in the general population, the importance of the problem among asthmatic children has yet to be documented.Sample and methods.Skin prick, intradermal and incremental challenge tests with lidocain were performed in 157 asthmatic children aged 8–15 years and compared with 72 nonasthmatic children of a similar age. All of the asthmatic subjects were allergic to at least one allergen, most frequently pollens and house dust mites. Prick testing began with an undiluted solution in patients without a history of allergy and with 1:100 dilution in those with a reaction history. Following negative prick testing, intradermal or incremental challenge tests were performed.Results.A total of 125 patients (80%) had been given local anaesthetics in the past, only three children gave history of an adverse local reaction. At the end of the tests, none of the subjects including controls, were found to have immediate or delayed‐type allergy to lidocain.Conclusions.Local anaesthetic allergy does not seem to be a serious problem among asthmatic children and testing in all asthmatic children is not warranted. Those with an adverse reaction history to local anaesthetics should be tested with these drugs.

Wheat ω-5 gliadin is a major allergen in children with immediate allergy to ingested wheat

Background: Sensitization to wheat by ingestion can lead to food allergy symptoms and wheat-dependent, exercise-induced anaphylaxis. Sensitization by inhalation causes bakers' asthma and rhinitis. Wheat allergens have been characterized at the molecular level in bakers' asthma and in wheat-dependent, exercise-induced anaphylaxis, in which ω-5 gliadin (Tri a 19) is a major allergen. However, little information is available regarding allergens responsible for hypersensitivity reactions to ingested wheat in children. Objective: The aim of this study was to examine whether children with allergy to ingested wheat have IgE antibodies to ω-5 gliadin. Methods: Sera were obtained from 40 children (mean age, 2.5 years; range, 0.7-8.2 years) with suspected wheat allergy who presented with atopic dermatitis and/or gastrointestinal and/or respiratory symptoms. Wheat allergy was diagnosed with open or double-blinded, placebo-controlled oral wheat challenge. Wheat ω-5 gliadin was purified by reversed-phase chromatography, and serum IgE antibodies to ω-5 gliadin were measured by means of ELISA. In vivo reactivity was studied by skin prick testing. Control sera were obtained from 22 children with no evidence of food allergies. Results: In oral wheat challenge, 19 children (48%) reacted with immediate and 8 children (20%) with delayed hypersensitivity symptoms. Sixteen (84%) of the children with immediate symptoms had IgE antibodies to purified ω-5 gliadin in ELISA. In contrast, IgE antibodies to ω-5 gliadin were not detected in any of the children with delayed or negative challenge test results or in the control children. The diagnostic specificity and positive predictive value of ω-5 gliadin ELISA were each 100% for immediate challenge reactions. Skin prick testing with ω-5 gliadin was positive in 6 of 7 children with immediate challenge symptoms and negative in 2 children with delayed challenge symptoms. Conclusion: The results of this study show that ω-5 gliadin is a significant allergen in young children with immediate allergic reactions to ingested wheat. IgE testing with ω-5 gliadin could be used to reduce the need for oral wheat challenges in children. (J Allergy Clin Immunol 2001;108:634-8.)

The necessity for dual food intake to provoke food-dependent exercise-induced anaphylaxis (FEIAn): A case report of FEIAn with simultaneous intake of wheat and umeboshi

Background: Food-dependent exercised-induced anaphylaxis (FEIAn) is classified among the physical allergies. Many different food allergens have been reported, but the pathophysiology of FEIAn remains unknown. Furthermore, provocation tests with a suspected food do not always succeed in patients with FEIAn. Objective: We sought to clarify and investigate causative foods and mechanisms of FEIAn in a 14-year-old boy. In addition, we tested in vivo and in vitro effects of cromolyn sodium in the same patient. Methods: We used open challenge tests for the provocation of FEIAn and measured changes in plasma histamine levels and FEV1. In addition, we investigated the mechanism of FEIAn in this case with in vitro histamine release testing. Results: The patient was diagnosed as having FEIAn by provocation testing with a simultaneous intake of wheat and umeboshi , but not when each food was eaten singly, followed by exercise. In addition, his plasma histamine level increased transiently and forced expiratory volume 1, expressed as a percentage change from baseline, decreased significantly. A synergistic effect on in vitro histamine release testing with 2 kinds of the causative foods was shown. Administration of cromolyn sodium proved to be effective on both the in vitro and in vivo tests. Conclusion: This is the first report of FEIAn provoked by the test with a simultaneous intake of 2 kinds of food. This case might in part explain negative challenge test results in patients with FEIAn. (J Allergy Clin Immunol 2001;107:1100-5.)

Celery allergens in patients with positive double-blind placebo-controlled food challenge

Background: Recently, for the first time, allergy to celery was confirmed by double-blind placebo-controlled food challenge (DBPCFC). Api g 1, Api g 4, cross-reactive carbohydrate determinants (CCD), and a 60 kDa allergen have been described as celery allergens. Objective: To get insights in IgE responses of patients with a positive DBPCFC to celery tuber (celeriac) compared with patients with a negative challenge test. Methods: Specific IgE to native and heated celery tuber and to recombinant Api g 1, the major celery allergen, were determined by enzyme allergosorbent test and immunoblotting. IgE binding to Api g 1, Api g 4, and CCD was confirmed by inhibition experiments that used recombinant Api g 1, recombinant Api g 4, pure N-glycans, and extracts of celeriac, lychee fruit, and pollens of birch, mugwort, and timothy grass as inhibitors. Results: Immunoblotting with sera from 22 patients with a positive DBPCFC to celeriac confirmed the presence of known allergenic structures: The major allergen Api g 1 (16 kDa) was recognized by IgE from 13 of 22 patients (59%). Another major allergen was CCD, determined by IgE reactivity in 12 of 22 patients (55%). Celery profilin, Api g 4, was recognized by IgE from 5 of 22 patients (23%). Conclusion: Our DBPCFC-positive patients exclusively presented IgE to known celery allergens, although the prevalences were slightly different than were previously reported. No obvious differences were found in patients with positive IgE antibody but negative challenge test. IgE binding to all 3 structures in celeriac extract was inhibited by birch pollen extract, whereas mugwort pollen extract could only inhibit IgE reactivity to Api g 4 and CCD. Inhibition experiments with a purified carbohydrate moiety clearly showed that the IgE epitope mannose-xylose-fucose-glycan (Manα1-6[Xylβ1-2]Manβ1-4GlcNAcβ1-4[Fucα1-3]GlcNAc) or a closely related structure is present in celeriac extract and is important in patients with clinical allergy to celery. (J Allergy Clin Immunol 2000;106:390-9.)

Anaphylactic reactions to raw eggs after negative challenges with cooked eggs

Anaphylactic reactions to raw eggs after negative challenges with cooked eggs

Clinical Significance of IgE–Binding Activity to Enzymatic Digests of Ovomucoid in the Diagnosis and the Prediction of the Outgrowing of Egg White Hypersensitivity

Background: We frequently encounter subjects without overt symptoms despite high IgE antibodies to egg white and its components. The measurements of these antibodies are not necessarily efficient for the diagnosis or the prediction of the outcome of egg allergy in children. Methods: Specific IgE antibodies to egg white and its components, including ovomucoid, ovalbumin, ovotransferrin and lysozyme, were measured by direct RAST assays. IgE–binding activity to ovomucoid degraded by pepsin, trypsin and chymotrypsin was examined by RAST inhibition. Thirty subjects were divided into two groups with positive (n=18; mean age ± SD = 42 ±25 months) and negative (n=12; mean age ± SD = 48 ±31 months) oral challenge tests with egg white antigens. The individuals with positive results to the first challenge tests were given the second provocation tests at mean intervals of 32 months. IgE–binding activity of the sera collected on the first challenge to these ovomucoid fragments was compared between subjects with positive and negative reactions to the follow–up challenge tests. Results: There were no significant differences in IgE antibody titers to egg white and its components between the positive and negative groups at the first and the second challenge tests. IgE–binding activity to ovomucoid digests after treatments with pepsin (p = 0.000008) and trypsin (p=0.037), except chymotrypsin (p=0.062), were significantly higher in subjects with positive challenge tests than in those with negative results. The difference was most remarkable in the IgE–binding to pepsin digests; the average concentrations (mean – SD and mean + SD) needed for 50% RAST inhibition in the positive group and in the negative group were 2.6 μg/ml (0.3 and 25) and 94.2 μg/ml (24.7 and 358.7), respectively. A significant difference was still observed in the inhibition tests using filtrates of pepsin digests with a membrane with MW 10,000 (p=0.014) and 3,000 (p=0.042) of cutoff. The concentration (mean= 0.8, mean – SD=0.2, mean + SD=3.4; μg/ml) of pepsin–treated ovomucoid required for 50% RAST inhibition in the subjects with positive second challenge results was significantly (p=0.033) lower than that (mean=6.8, mean–SD=0.6, mean + SD=73.9) of the negative group. Conclusion: IgE–binding activity to pepsin–digested ovomucoid was of diagnostic value to distinguish the challenge–positive subjects from the negative subjects. Subjects with high IgE–binding activity to pepsin–treated ovomucoid are unlikely to outgrow egg white allergy.

Predicting the outcome of the CaNa2EDTA challenge test in children with moderately elevated blood lead levels.

The Centers for Disease Control and Prevention suggests the challenge test for children whose blood lead levels are 1.21-2.12 micromol/L (25-44 microg/dL). However, the challenge test is difficult to perform. By identifying children who are likely to have a negative challenge test, a medical provider can minimize the number of children undergoing this test. The goal of this study was to identify common tests that are likely to predict the outcome of the challenge test. It was conducted as a clinical descriptive study from a series of patients who underwent a CaNa2EDTA challenge test. Results from 178 challenge tests were eligible for analysis. The mean age of children undergoing the challenge test was 38.2 months, and the mean blood lead level was 1.83 micromol/L (38 microg/dL). Blood lead level, age, erythrocyte protoporphyrin level, and RATE (a measure of the rate of change of the blood lead level) were either not sensitive or not specific in predicting the outcome of a challenge test. However, based on a logistic regression model using blood lead level, age, and RATE, we determined criteria that would have identified all children who would have had a positive challenge test while excluding most children who would have had a negative challenge test. Based on this model, we recommend that the challenge test be conducted on children >=36 months of age who have a blood lead level between 1.45 and 1.64 micromol/L (30-34 microg/dL) and on children who have a blood lead level 1.69-2.12 micromol/L (35-44 microg/dL) regardless of age. This approach would have tested all children who subsequently would have had a positive challenge test while testing only 39% of children who would have had a negative challenge test.

Effect of Initial Gestagen Treatment on Bleeding Patterns in Postmenopausal Women Receiving Continuous Combined Hormone Replacement Therapy

The purpose of this prospective study was to investigate the association of initial gestagen treatment with future breakthrough bleedings during continuous combined hormone replacement therapy. The predictability of progesterone challenge test on bleeding has also been investigated. Eighty-six naturally postmenopausal women, of whom 38 received initial gestagen treatment (5 mg medroxyprogesterone acetate, twice daily, for 10 days) and 48 did not, were included in this prospective study. Patients were followed for 6 months, and any bleeding occurring during therapy was recorded. Of the 48 patients who received continuous combined hormone replacement therapy without initial gestagen treatment, 23 (48%) had a bleeding episode. Of the 38 patients who received the same therapy with initial gestagen treatment, 13 (34.2%) had bleeding. There was a trend toward decreased breakthrough bleeding in the second group, which did not achieve significance. The mean time before bleeding was 6.76 weeks in the first group and 11.75 weeks in the second group; the difference was statistically significant (p < 0.05). Of the 28 patients with a negative progesterone challenge test at the onset of therapy, eight (28.6%) had bleeding during hormone replacement therapy. Of the 10 patients with a positive challenge, five (50%) had bleeding. The difference was not statistically significant. Patients who receive gestagen treatment before the onset of continuous combined hormone replacement therapy tend to experience breakthrough bleeding less frequently and later during the therapy. The response to progesterone challenge does not predict future bleeding during continuous combined hormone replacement therapy.

In vitro lymphocyte proliferation in the diagnosis of allergy to phenoxymethylpenicillin.

The aim of this study was to investigate in vitro lymphocyte proliferation in the diagnosis of allergy to phenoxymethylpenicillin (PcV), comparing chemically reactive PcV, added to cell cultures in unconjugated form, to a PcV-PLL (poly-L-lysine) conjugate as antigens. Side-chain specificity of lymphoproliferative responses was investigated with reactive benzylpenicillin (PcG) and bacampicillin. Seventeen patients with a history of hypersensitivity reactions in connection with PcV treatment were studied by means of the lymphocyte transformation test (LTT), the radioallergosorbent test (RAST), skin tests (prick and intracutaneous), and oral challenge with PcV. LTT was also performed in 20 control subjects exposed to PcV therapeutically, and in eight subjects with occupational exposure to this penicillin. Nine patients had a positive in vivo test to PcV (five by oral challenge, three by intracutaneous test, and one by both tests), and six were challenge-negative. When reactive PcV was used as antigen in LTT, positive LTT responses were observed in five of the nine patients with a positive in vivo test, and two of them were also side-chain specific. Positive LTT responses with reactive PcV also correlated with a positive RAST in five of seven subjects. None of the six patients with a negative challenge test, and only one of the 28 controls showed a positive LTT result with reactive PcV. Thus, the specificity of LTT with reactive PcV was 96%. In contrast, when PLL-conjugated PcV served as antigen, four challenge-negative subjects and 11 controls were LTT-positive. The results of this study indicate that LTT with chemically reactive PcV could be useful as an in vitro complement in the diagnosis of PcV allergy and as a tool to reveal the side-chain specificity of peripheral blood lymphocytes. A positive LTT to PLL-conjugated PcV may be an indicator of immunization, but not necessarily allergy, to the penicilloyl structure.

P-23. Evaluation of the Results of Transvaginal Sonography in Patients in the Postmenopause Period with Negative Progestational Challenge Test Who Intended to Use HRT

P-23. Evaluation of the Results of Transvaginal Sonography in Patients in the Postmenopause Period with Negative Progestational Challenge Test Who Intended to Use HRT

Clinical cross-reactivity between amoxicillin and cephadroxil in patients allergic to amoxicillin and with good tolerance of penicillin

In recent years, patients allergic to amoxicillin (AX) but with good tolerance of penicillin G (PG) have been described. It has been suggested that the epitope implicated in this type of sensitization might be located on the side-chain of the AX molecule. Thus, cross-reactivity between AX and cephadroxil (CEPH), a cephalosporin which shares an identical side-chain with AX, is suspected. This study aimed to demonstrate clinical cross-reactivity between AX and CEPH in patients allergic to AX and showing good tolerance of PG. In 76 of 576 subjects with suspected allergic reaction to PG and/or AX, the diagnosis of allergy was confirmed. All of these had specific IgE to PG, penicillin V, or AX, and/or positive skin tests to PPL (penicilloyl-polylysine), or MDM (minor determinant mixture), or PG, or AX, and/or positive challenge tests with PG and/or AX. Sixteen subjects (21%) allergic to AX (11 with positive skin test and five with positive challenge test to AX) and good tolerance of PG (all with negative parenteral challenge test) were selected. These 16 patients were subsequently challenged with CEPH (up to 500 mg). Fourteen patients tolerated CEPH, and two (12%) had an immediate allergic reaction. Our study indicates that allergy to the side-chain of aminopenicillins seems to have little clinical relevance in patients with allergic reactions to aminopenicillins but with good tolerance of PG, as 88% of patients with this clinical characteristic tolerate a cephalosporin which shares an identical side-chain. It seems that IgE from most of these patients recognizes an epitope different from the side-chain and the beta-lactam ring.

Diagnostic validation of specific IgE antibody concentrations, skin prick testing, and challenge tests in chemical workers with symptoms of sensitivity to different anhydrides

Background: The diagnostic possibilities of sensitization to various acid anhydrides are limited because of the lack of standardized allergens for the different test systems. This makes the diagnosis of IgE-mediated sensitization caused by occupational exposure difficult. Methods: We prepared conjugates of human serum albumin with phthalic, maleic, trimellitic, and pyromellitic anhydrides to be used for IgE estimation by enzyme-allergosorbent test, skin prick tests, and nasal and bronchial challenge tests. Nine anhydride workers, who complained of various respiratory symptoms, were studied. Results: Of the nine workers, four had immediate-type skin test responses to one or more conjugates. All four subjects had elevated IgE concentrations in addition to two other workers. Three of six nasal challenges and four of nine bronchial challenges resulted in positive responses. All but one of the positive nasal or bronchial test responses were associated with elevated IgE levels. The seven positive challenge test results included five positive skin test responses. On the other hand, in all but two of the subjects with negative challenge test results, no specific IgE could be detected. In these two subjects the negative results were associated with low levels of IgE, and in one, with the absence of asthma. None of the results of tests with unconjugated anhydrides were positive. Conclusions: Anhydrides investigated in this study can induce IgE-mediated hypersensitivity, which can be diagnosed by using the respective human serum albumin in estimation of specific IgE and in skin, nasal, and bronchial challenge tests. Estimation of IgE was demonstrated to be more sensitive than skin prick testing. ( J Allergy Clin Immunol 1995;96:489-94.)