Skin testing versus radioallergosorbent testing for indoor allergens

BACKGROUND: Skin testing (ST) is the most common screening method for allergy evaluation. Measurement of serum specific IgE is also commonly used, but less so by allergists than by other practitioners. The sensitivity and specificity of these testing methods may vary by type of causative allergen and type of allergic manifestation. We compared ST reactivity with serum specific IgE antibodies to common indoor allergens in patients with respiratory allergies. METHODS: 118 patients (3 mo-58 yr, mean 12 yr) with allergic rhinitis and/or bronchial asthma had percutaneous skin testing (PST) supplemented by intradermal testing (ID) with those allergens suspected by history but showed negative PST. The sera were tested blindly for specific IgE antibodies by the radioallergosorbent test (Phadebas RAST). The allergens were D. farinae (118), cockroach (60), cat epithelium (90), and dog epidermal (90). Test results were scored 0-4; ST >/= 2 + and RAST >/= 1 + were considered positive. RESULTS: The two tests were in agreement (i.e., either both positive or both negative) in 52.2% (dog epidermal) to 62.2% (cat epithelium). When RAST was positive, ST was positive in 80% (dog epidermal) to 100% (cockroach mix). When ST was positive, RAST was positive in 16.3% (dog epidermal) to 50.0% (D. farinae). When RAST was negative, ST was positive in 48.5% (cat epithelium) to 69.6% (D. farinae). When ST was negative, RAST was positive in 0% (cockroach) to 5.6% (cat epithelium). The scores of ST and RAST showed weak to moderate correlation (r = 0.24 to 0.54). Regardless of history of symptoms on exposure, ST was superior to RAST in detecting sensitization to cat epithelium and dog epidermal. CONCLUSION: For all four indoor allergens tested, ST was more sensitive than RAST. When both tests were positive, their scores showed poor correlation. Sensitizations to cat epithelium and dog epidermal are common, even in subjects who claimed no direct exposure.     

Allergy to penicillin: fable or fact?

OBJECTIVE--To assess whether, on the basis of one blood test, penicillin allergy might be excluded sufficiently for general practitioners to give oral penicillin to patients claiming a history of penicillin allergy. DESIGN--Prospective study of patients referred by general practitioners. SETTING--Outpatient allergy clinic in a district general hospital. PATIENTS--175 referred patients who gave a history of immediate type reaction to penicillin, of whom 144 attended as requested and 132 completed the investigations. MAIN OUTCOME MEASURES--History and examination, serum radioallergosorbent test to phenoxymethylpenicillin and benzylpenicillin, and oral challenge with penicillin. RESULTS--Of 132 patients, four were confirmed to have penicillin allergy by the radioallergosorbent test and 128 had an oral penicillin challenge without ill effect. CONCLUSIONS--Most patients who gave a history of penicillin allergy are not so allergic, and their actual allergic state should be substantiated whenever feasible. For patients reporting minor or vague reactions negative findings with a radioallergosorbent test to phenoxymethylpenicillin and benzylpenicillin provide sufficient evidence to give oral penicillin safely.     

支气管扩张合并支气管哮喘患者的病原菌检测及危险因素分析

目的分析支气管扩张合并支气管哮喘患者的病原菌及危险因素。方法选取湖州市中心医院115例支气管扩张合并支气管哮喘患者作为观察组,另选取同期110例健康体检者作为对照组。分析患者病原菌的组成、耐药性及发病危险因素。结果观察组患者送检痰样本经痰培养,阳性检出者68例,阳性率为59.13%(68/115)。全部样本共分离出104株病原菌,其中革兰阴性菌92株(以铜绿假单胞菌最多,占54.81%),革兰阳性菌8株,真菌4株。药敏试验结果表明革兰阴性菌对复方新诺明、头孢曲松、左旋左氧氟沙星和阿莫西林/克拉维酸等药物的耐药性均较高,对妥布霉素、亚胺培南、头孢哌酮/舒巴坦和哌拉西林的耐药性较低。Logistic回归分析显示,吸烟史、药物过敏史、食物过敏史、过敏性鼻炎、哮喘、过敏性肺炎、慢性支气管炎及慢性阻塞性肺疾病均是支气管扩张伴支气管哮喘发生的危险因素。结论支气管扩张合并支气管哮喘患者其病原菌以革兰阴性菌为主,吸烟史、药物过敏史、食物过敏史、过敏性鼻炎等是支气管扩张伴支气管哮喘发生的危险因素。     

Skin testing for allergy in children.

In diagnostic testing for IgE-mediated allergy in children the skin-prick test is preferred because it is safer, less painful and more specific than the intracutaneous test, and cheaper and more sensitive than the radioallergosorbent test (RAST). The intracutaneous test and RAST are useful in certain circumstances, however. While a positive result from any of these tests indicates hypersensitivity, it does not necessarily mean that the allergen giving the positive result is responsible for the patient''s symptoms. That can only be decided by interpreting the result in light of the allergy history. This paper outlines the indications for the prick test, the allergens that may be employed, the method of doing the test, and its place among the other tests that are used in a modern pediatric allergy practice.     

Radioimmunologic tests in children with pruritus and with a combination of pruritus and allergic respiratory disease

Radioimmunological tests were carried out in 180 children with pruritus and 167 children with pruritus and allergic respiratory diseases. Difference between these groups was statistically insignificant in case of food allergy. Results of RAST were more often positive in case of respiratory allergy in the patients with pruritus and coexisting allergic respiratory diseases than in patients with skin involvement only. Reaction was more intense and allergy polyvalence measured with RAST was higher. All differences were statistically significant (p less than 0.001 or 0.01). Mean IgE levels was higher in children of all age groups in case of pruritus coexisting with allergic respiratory diseases.     

Allergy to insect stings. IV. Diagnosis by radioallergosorbent test (R.A.S.T.)

Radioallergosorbent tests (RAST(s)) have been developed and assessed for the diagnosis of insect hypersensitivity by using a purified allergen from honeybee venom, phospholipase A, and crude yellow jacket venom. Sera from 193 patients positive both by history and skin test to one of these insects were compared with various groups of control sera. Eighty percent of sera from skin test-positive patients were RAST positive; positive RAST were found in 16% of sera tested from skin test-negative patients. A highly positive RAST correlates well with a positive skin test and clinical sensitivity, but serum IgE is not measurable in many patients with mast cell or basophil bound antibody. Since biologically important reactions of antigen with IgE require that the antibody be cell bound, skin testing would be preferred to RAST if one were limited to a single test for the diagnosis of insect allergy.     

Lymphocyte responses to food antigens in food sensitive patients with allergic tension-fatigue syndrome

Scores of radio allergosorbent test (BAST) for cow's milk or buckwheat flour and proliferative responses of peripheral blood mononuclear cells (PBMCs) to bovine serum albumin and-lactoglobulin or buckwheat flour were measured in cow's milk or buckwheat flour sensitive patients with allergic tension-fatigue syndrome. In all 3 cow's milk sensitive patients with allergic tension-fatigue syndrome, RAST scores for cow's milk were negative or slightly positive, but PBMCs well responded to bovine serum albumin and-lactoglobulin, but not to ovalbumin. In a buckwheat flour sensitive patient with allergic tension-fatigue syndrome, RAST scores for buckwheat flour were negative, but PBMCs well responded to buckwheat flour, but not to ovalbumin, bovine serum albumin and-lactoglobulin. Conversely, in cow's milk or buckwheat flour sensitive patients with immediate allergic symptoms, RAST scores for offending foods were positive although PBMCs did not respond to offending food antigens. These results suggest that proliferative responses of PBMCs to food antigens are very useful for detection of offending foods in allergic tension-fatigue syndrome.     

青霉素过敏人群IL-18血清浓度以及启动子区基因多态性研究

目的：探讨青霉素类抗生素过敏反应与IL-18及其基因多态性的关系。方法：采用ELISA方法检测50例正常对照和67例过敏患者血清中IL-18水平,PCR-SSP法检测IL-18启动子区多态性位点的基因型。结果：青霉素过敏组IL-18血清浓度显著高于正常对照组（P〈0.01）,且随着皮试反应程度的增强,IL-18浓度也随之升高;青霉素过敏病人IL-18-607位点A等位基因出现频率显著高于对照组（P〈0.01）,CA＋CC基因型降低了青霉素过敏发生的风险性[2=5.868,P〈0.05,OR=3.910,95%Cl（1.225,12.478）]。不同基因型患者血清中IL-18浓度无显著性差异。结论：青霉素过敏反应与IL-18升高有关,IL-18基因启动子区-607C/A位点多态性与青霉素过敏显著相关。     

Diagnosis of penicillin allergy by skin testing: the Manitoba experience.

The reliability of skin testing in the diagnosis of penicillin allergy was studied in 86 adults and 167 children with a history of possible hypersensitivity reactions to penicillin. Skin testing was done with the major antigenic determinant of benzylpenicillin and minor determinants of benzylpenicillin, ampicillin, cloxacillin, methicillin and cephalothin. The overall frequency of positive skin reactions was 11.5%. Among the patients with positive skin reactions about half had a history of immediate or accelerated reactions to penicillins, but 2 of 11 adults and 50% of the children in this group had a history of maculopapular rash of delayed onset. There was a low frequency of positive skin reactions when there was a long interval between the times of clinical reaction and skin testing. Of 169 patients reacting negatively to skin testing who received a specific drug challenge only 2 manifested mild urticaria; this indicates the reliability of the skin tests in predicting penicillin allergy. The major and minor determinants of benzylpenicillin were the most useful reagents. One fifth of the patients with penicillin hypersensitivity would have been missed if the major determinant of benzylpenicillin alone had been used for skin testing. The additional use of the minor determinants of other penicillin derivatives, however, did not increase substantially the clinical reliability of the skin testing procedure.     

Detection of Allergy to Penicillin and Other Antigens by In-vitro Passive Sensitization and Histamine Release from Human and Monkey Lung

Preparations of chopped human and monkey lung were used to estimate the reaginic activity of serum from allergic patients. The lung preparation was passively sensitized by incubation with serum taken from the patients, and then challenged with the antigen responsible for the allergy. Measurement of the histamine released from the lung gave a quantitative assessment of the level of reaginic activity in the patient''s serum.Tests were done on patients allergic to four natural antigens, including grass pollen, and to penicillin. Human lung proved more sensitive and possibly more specific than monkey lung in testing for natural allergies. The results of testing for penicillin allergies were less satisfactory, possibly because of the difficulty of reconstructing the appropriate antigen.     

Toward an in vitro test for the diagnosis of allergy to penicillins. Synthesis, characterization, and use of beta-lactam and beta-lactam metabolite poly-L-lysines which recognize human IgE antibodies.

Conjugates of poly-L-lysine (PLL) containing a penicillin or a penicilloyl residue were prepared and characterized by 1H NMR and by size-exclusion (SE) HPLC. These conjugates were used in a radio allergo sorbent tests (RAST) test for the determination of allergy toward beta-lactams. The chemiometric evaluation of the data indicates that allergy to amoxycillin is different from allergy to the other beta-lactams tested. Furthermore, careful chemical characterization of the conjugates appears to be crucial to obtain meaningful information from the RAST data.     

The role of phadiatop in the screening of respiratory allergy

Phadiatop is a new in vitro screening test for respiratory allergy. This test, based on the RAST procedure, detects in serum, the presence of specific IgE to a mixture of common inhalent allergens. Among 70 patients (26 children and 44 adults) consulting for respiratory syndrome, Phadiatop was positive in 31 cases. There were a good correlation between this new test and skin tests (59% for adults and 92% for children), total IgE (70% for adults and 65% for children) and RAST (93% for adults and 96% for children). Phadiatop, with a specificity of 100%, a sensitivity of 82% (76% for adults and 92% for children) and an efficiency of 90% (86% for adults and 96% for children), is a more accurate test than total IgE and could be an excellent in vitro screening test for respiratory allergy.     

Minor pollinosis fromCryptomeria japonica in Varese,northern Italy. Aerobiological monitoring and main clinical features

In the last 2 years we have conducted an aerobiological monitoring program ofCryptomeria japonica, a plant belonging to the family of Taxodiaceae that sometimes causes pollinosis in the period from February to April. Throughout 1994, we checked the incidence of its sensitization and the clinical effects in 85 subjects with correlated seasonal symptoms, who gave a positive skin prick test (SPT) for Betulaceae and/or Corylaceae. Twenty-five patients (29.4%; 19 M; 6 F; mean age, 38.8 years) all with oculorhinitis, were SPT positive to an allergenic extract ofCryptomeria. RAST confirmed this positivity in 44% of the cases. No patients showed monosensitization forCryptomeria to either SPT or RAST. Two subjects gave a positive result on specific nasal provocation. RAST inhibition showed no cross-reaction betweenCryptomeria and birch pollen. During the pollen season each patient made a list, scoring symptoms and specifying any drugs used, so we could correlate these elements with aerobiological observations. The pollen concentration probably exceeded the allergizing threshold forCryptomeria on 8 days during 3 months of recording. The intensity and duration of symptoms seemed to be mainly influenced by sensitization to Betulaceae and Corylaceae. It is thus possible that a combination of minor pollinosis may produce seasonal symptoms in allergic patients.     

Allergy testing: comparison of skin and in vitro tests of allergic reagin.

Skin tests have been used for many years to detect reaginic antibodies in the investigation of allergic patients. Recently in vitro assays of allergic reagins, including the radioallergosorbent test (RAST) and the rat mast cell test (RMCT) have become available. A comparison of the clinical usefulness of these tests suggested that skin tests and the RAST are of comparable diagnostic accuracy and reliability. The RMCT was found to be poorly reproducible and unreliable. For routine cases skin tests should continue to be the procedure of choice. The RAST may reasonably be used when skin tests are unreliable, impractical or contraindicated. The RAST may also be helpful in some cases in resolving discrepancies between skin test results and the clinical history.     

Seasonal allergic asthma and non-specific bronchial responsiveness

Summary Bronchial responsiveness to methacoline (PD20 FEV1 mcg) was measured in 64 non smoker asthmatic patients with baseline FEV190% predicted. Patients underwent skin prick tests (SPT) and RAST.Allergic patients had: SPT3+ and RAST-score>II class to the same antigen and correlation with asthmatic symptoms; non allergic patients had negative SPT and RAST. We divided patients in four groups: 1st) allergic seasonal asthmatics before pollen season; 2nd) allergic seasonal asthmatics during pollen season; 3rd) allergic perennial asthmatics; 4th) non-allergic perennial asthmatics.A significant difference in log PD20 was observed between 1st and 2nd group (p<0.0005); between 1st and 3rd group (p<0.0005); between 1st and 4th group (p<0.0005). In allergic seasonal asthmatics before pollen season 10/20 subjects were non-responsive to methacholine (PD201600 mcg), while in 2nd, 3rd and 4th group no subjects were non-responsive.The authors conclude that non-specific bronchial hyperresponsiveness to methacoline is not constant in seasonal allergic asthmatics out of pollen season.     

Family history of allergy and symptoms of atopic dermatitis

Three hundred sixty five children and hundred thirty nine adults with atopic dermatitis were divided into three groups. Group A included patients with negative family history of allergy; group B--allergy history in one parent or his family; group C--allergy in both parents or their families. It was found that total IgE level was higher in patients of group C in comparison with group A. Similarly, bronchial asthma and/or rhinitis coexisted more frequently, incidence of urticaria was higher and its onset earlier in patients of group C. The results noted in patients of group B occupied middle position between those in group A and group C. Results related to the incidence of RAST positive reactions and multiple sensitivity were similar but the differences were lower. Radioimmunologic assays were performed only in part of the tested patients.     

Secondary prevention of allergic symptoms in a dairy farmer by use of a milking robot

Background

Allergic sensitization and reactions to guinea pig (Cavia porcellus) have been well documented in laboratory animal handlers, primarily manifesting as rhinitis, conjunctivitis, and asthma. Severe allergic reactions, however, are rare.

Methods

We report two patients with severe allergic reactions following non-occupational exposure to guinea pigs. The first patient, an 11-year-old female, developed ocular, nasal, skin and laryngeal edema symptoms immediately after handling a guinea pig. The second patient, a 24-year-old female, developed symptoms of isolated laryngeal edema after cleaning a guinea pig cage. Percutaneous skin testing, RAST, ELISA and ELISA inhibition testing with guinea pig extract were performed.

Results

Both patients had IgE-mediated allergy to guinea pig confirmed by ELISA and either RAST or skin testing. ELISA inhibition studies confirmed the specificity of the IgE reactivity to guinea pig.

Conclusion

Severe IgE-mediated reactions can occur following non-occupational guinea pig exposure. Physicians should be aware of this possibility.     

THE MANAGEMENT OF ALLERGIC PATIENTS—The Role of the Internist

There has been an increasing trend in the United States toward intensive specialization in allergic diseases. Whereas the tendency toward specialization has led to greater knowledge of the scientific aspects of allergic phenomena, it has somewhat diverted the specialists'' attention from the many clinical problems that await solution.Effective treatment of the allergic patient depends in no small measure on the broad viewpoint and clinical experience of the internist. This fact has been reemphasized by the growing awareness of the significance of the secondary or precipitating causes, such as climatic, nutritional, hormonal and psychogenic factors which influence allergic manifestations. Overemphasis on specialization in allergic diseases with their wide ramifications may defeat the main objective—a successful therapeutic result.To meet this challenge, the internist should be trained in allergy and yet retain a broad approach to the more basic problems of internal medicine. This objective may be attained by certain modifications in undergraduate medical instruction in allergy. Postgraduate training sponsored by our national allergy societies affords internists an excellent opportunity to advance their knowledge of clinical allergy.     

Measurement of absolute amounts of antigen-specific human IgE by a radioallergosorbent test (RAST) elution technique.

A technique for the absolute quantification of antigen-specific human IgE is described. It employs elution of a calculable amount of antigen-specific IgE from an allergosorbent-antibody complex by means of alkaline pH treatment, followed by measurement of the IgE content of the eluate with a modified radioimmunosorbent test (RIST). With this method IgE antibody directed against the benzylpenicilloyl determinant of penicillin (BPO) was measured quantitatively in sera from seven penicillin allergic patients. IgE specific for ragweed antigen E was measured in sera from 33 ragweed allergic patients. Values obtained for IgE anti-BPO ranged from 19 to 1806 ng/ml and comprised from 1.3 to 27.5% of total serum IgE. Values of IgE anti-antigen E ranged from 9 to 1807 ng/ml, comprising from 3 to 84% of total serum IgE. Excellent correlation (r = 0.99; p less than 0.001) was obtained for both antigen systems between values determined by the RAST elution technique and by simple RAST assay with interpolation from a reference serum of known specific IgE content as determined by the elution technique may be needed only for primary standardization of reference sera.     

Chlamydia trachomatis infection in rural Nova Scotia.

OBJECTIVE: To examine the demographic characteristics of patients who underwent testing for Chlamydia trachomatis and to determine the clinical and behavioural characteristics and the types of treatment for those who had positive test results. DESIGN: Case series. SETTING: Rural county in Nova Scotia. PATIENTS: All residents of the county for whom testing for C. trachomatis was ordered at the regional hospital from Sept. 1, 1990, to Mar. 31, 1991. MAIN OUTCOME MEASURES: Rates of testing and of positive test results by age and sex. Comparison of patient and physician characteristics in relation to testing rates. RESULTS: Of the 1116 patients tested 58 (5.2%) had positive test results. Females accounted for 82.8% of those with positive results whose sex could be determined. Among the females the mean age of those with a positive result was 22.3 years, as compared with 27.5 years for those with a negative result (p < 0.0001). Females 15 to 19 years of age were less likely to have a test performed than women 20 to 29 years and were more likely to have a positive test result than the women in the older groups. Almost 9% of the testing among the females was in those over 39 years of age, although no infection was seen in this age group. The number of tests ordered per general or family practitioner varied from 1 to 154; the physicians'' sex, practice location and length of time in practice did not predict the rates of positive test results. Treatment was most often in keeping with that recommended by national guidelines. Four (8.5%) of the 47 patients with positive results who were interviewed were not aware of their diagnosis, either because they had not returned for follow-up or had not being notified by the physician''s office. CONCLUSIONS: The frequency of testing for C. trachomatis infection may be less than is desirable among young patients, who, if tested, are more likely than older patients to have positive results. More understanding of the diagnostic approach taken by physicians is needed.