Value of the case history in the diagnosis of allergic state and the detection of allergens

Detailed histories taken in eighty-one patients suffering from perennial asthma and rhinitis were analysed independently by three trained allergists and their conclusions were compared to the results of three tests: (1) concentration of total serum IgE; (2) skin tests and (3) radioallergosorbent test (RAST). In eleven patients (14%), the three investigators disagreed when estimating the allergic nature of the symptoms. Ten out of forty-four patients (23%), unanimously predicted not to be allergic, had high levels of total serum IgE and skin tests and RAST clearly positive for one or more allergens. The allergists suspected 47% of the allergens detected by skin tests and 55% of those detected by RAST. The case history was the test which most often gave information at odds with that suggested by the other three tests. Our study indicates therefore that a case history not even suggestive of allergy should be complemented by additional tests.     

Specific IgE antibodies in atopic eczema

Radioallergosorbent tests (RAST'S) with 35 antigens and total serum IgE levels were performed on sera from 25 patients with atopic eczema, ranging from mild to very severe, who had been evaluated clinically and, when possible, skin-tested to inhalant allergens. IgE levels varied from 95 to 112,000 I.U., with a geometric mean of 2,200 I.U. Individual patients' sera gave an average of 8.4 positive RAST's to 14 inhalant allergens with a range of from 1 to 14 positive tests. The correlation of RAST with skin tests averaged 55 per cent with no difference observed with either the scratch or the prick methods. The degree of correlation was not related to severity of eczema. In eczema patients the great majority of noncorrelating tests were RAST positive and skin-test negative, unlike the noncorrelating tests found in children with asthma and allergic rhinitis, where there are more positive skin tests with negative RAST. The 25 sera were tested by RAST with 18 food antigens and the various sera gave from 1 to 18 positive tests, with an average of 9.7. IgE antibodies reacting with at least one of the DPT antigens were found in 10 of the 25 sera. Sera from 4 of the patients studied contained IgE antibodies that combined with all 35 antigens studied. Control RAST's with these sera were negative. This study shows that much of the elevation of serum IgE observed in atopic eczema represents specific IgE antibodies that can combine with common antigens with relatively high affinity.     

Value of a new screening test for respiratory allergy

Phadiatop (Pharmacia) is a new in vitro screening test for respiratory allergy which detects in serum the presence of specific IgE to a mixture of common inhalant allergens; results are either positive or negative. Among 100 patients suffering from rhinitis and/or asthma, investigated with 15 skin prick tests (SPT) and RAST for frequent allergens, the Phadiatop was positive in 63: all 63 had at least one positive SPT and RAST (specificity: 100%). Conversely, ther were 67 patients who had a positive RAST for at least one allergen: among these 67 the total IgE concentration in serum was high (greater than 100 kU/l) in 43 (64%) and the Phadiatop was positive in 63 (94%). Phadiatop was negative in serum obtained from 10 cord bloods and 10 non-allergic subjects (disease-free, 15 negative SPT and RAST). Results of the radio-immunoassay originally proposed by the manufacturer were similar to those obtained with a modified enzymo assay using a fluorometric substrate. In the prediction of respiratory allergy, Phadiatop was found to be specific and more accurate than the determination of total IgE in serum.     

Clinical significance of specific IgE determination on nasal secretion

The clinical use of RAST on the nasal secretions was investigated in seventeen atopic patients, with asthma or rhinitis, who had shown at a first diagnostic screening, some difficulties in the identification of the responsible allergen(s). The results of the skin tests, of the RAST on the serum and on the nasal secretions and of the specific provocation test (bronchial or nasal) were compared. In some cases the basophil degranulation test was performed. The results of the RAST on the nasal secretions were in perfect agreement with the provocation test. The skin tests and the RAST on the serum showed many discrepancies, particularly for Dermatophagoides, epidermal derivatives of cat and dog and moulds, and less frequently for Graminaceae and other pollens. It is concluded that RAST analysis on nasal secretions is useful in clinical diagnosis of allergy especially for Dermatophagoides, epidermal derivatives and moulds. Most false positive results were observed with the RAST on serum; in fifteen cases it was positive, while all the other tests, basophil degranulation test included, were negative. The data suggest that IgE may have a low affinity for basophil receptors.     

Allergy from cellulase and xylanase enzymes

Modern biotechnical methods have enabled production of many new types of potentially allergenic proteins. Enzymes have long been known to be respiratory allergens, but relatively few cases of skin allergy have been reported. Here we describe four patients who developed occupational allergic respiratory symptoms, three with bronchial asthma and one with allergic rhinitis, caused by cellulase and/or xylanase enzymes. Each patient also had urticarial symptoms after skin contact with these enzymes. In addition, one of the patients had allergic contact dermatitis from cellulase, and one from xylanase. Allergic contact dermatitis was verified by positive patch tests with the enzymes, and the immediate allergy was revealed by skin prick tests, specific IgE determinations (RAST) and RAST-inhibition tests. All patients had positive RASTs to both cellulase and xylanase. In the RAST inhibition test 20 microliters of cellulase brought about a 94% inhibition, indicating the specificity of the RAST. Xylanase (20 microliters, 5% w/v) gave an 92% inhibition of cellulase RAST, indicating cross-reactivity between cellulase and xylanase. Three patients have been able to continue at their previous places of work, but at different worksites. One of the patients requires continuous medication for asthma and had to change her job because of persistent symptoms.     

Widespread immunoglobulin E-mediated hypersensitivity in the Sudan to the “green nimitti” midge,Cladotanytarsus lewisi (diptera: Chironomidae): I. Diagnosis by radioallergosorbent test

A radioallergosorbent test (RAST) has been developed for the diagnosis of hypersensitivity to “green nimitti” chironomid midges of the species Cladotanytarsus lewisi. There was a high percentage binding of ¹²⁵I-anti-IgE to the allergen particle complex by serum from subjects who were clinically hypersensitive, and the RAST was inhibited following incubations of allergic sera with an extract of the allergen. In 104 hypersensitive subjects (i.e., those with a positive skin test or clinical history of bronchial asthma, with or without rhinitis) and 21 controls, the RAST appeared to be specific and of diagnostic value: (1) The percentage binding was appreciably higher in 38 symptomatic individuals (group I) with strongly positive skin tests as compared with 36 patients with moderate skin reactivity (group II). (2) Seven symptomatic subjects with negative skin tests (group III) had a positive (>6% binding) green nimitti RAST. (3) Positive RASTs were demonstrable in 16 and of 17 patients with positive skin tests in whom the history was equivocal (group IV). (4) Six asymptomatic individuals with positive skin tests (group V) had low RAST values. (5) Six asymptomatic Sudanese controls with negative skin tests gave similar values to those of the group V subjects. (6) All of the sera from 15 nonatopic United Kingdom controls gave less than 6% binding of ¹²⁵I-anti-IgE. There was no statistical correlation between the concentrations of total IgE and the green nimitti RAST values. These results suggest that the RAST may be useful diagnostic test in green nimitti hypersensitivity and may also be of value in studies on the epidemiology and in the monitoring of treatment of this important and widespread allergy problem in the Sudan.     

Nonallergic rhinitis with eosinophilia (NARES syndrome): Clinical and immunologic presentation

Fifty-two patients with perennial nasal symptoms of sneezing paroxysms, profuse watery rhinorrhea, and pruritus of the nasopharyngeal mucosa in an “on-again-off-again” symptomatic pattern have been clinically and immunologically characterized. Historically, age at onset of symptoms showed equal distribution from the first through the fifth decades, and the duration of symptoms at diagnosis ranged from 3 mo to 40 yr (mean 9 yr). Trigger factors associated by the 52 patients with the acute onset of nasal symptoms were none or unknown in 22 (42%), weather changes in 16 (31%), odors in eight (15%), and noxious or irritating substances in six (12%). No patients had a history or physical examination consistent with nasal polyposis, bronchial asthma, recurrent sinusitis, nor otitis media. Fifty percent had a negative family history for either chronic rhinitis or bronchial asthma. Nasal secretion smears revealed marked eosinophilia during symptomatic periods. Intradermal skin tests were negative in 49 patients. Serum radioallergosorbent test (RAST) confirmed immediate hypersentitivity skin tests in two of the three patients with positive skin tests. Mean total eosinophil count was 218/mm³. Quantitative immunoglobulins were normal in all patients. Mean serum IgE was 74 IU/ml. Methacholine bronchial challenge was negative in 37 of 37 patients tested. An open aspirin challenge was negative in 13 of 13 patients tested. Spontaneously collected nasal secretions or 0.9% saline nasal washes were analyzed for percent eosinophils, total protein, IgG, IgA, IgE, and RAST to six perennial aeroallergens in 31 of the 52 patients. Neither elevated total IgE nor evidence of specific IgE was found in the study patients' nasal secretions. This report describes 52 patients with symptoms similar to those seen in perennial allergic rhinitis. A characteristic pattern of symptomatic presentation and a paucity of the in vivo and in vitro findings associated with IgE-mediated nasal disease distinguishes this homogeneous disorder from perennial allergic rhinitis.     

Serum IgE antibodies to Trichophyton in patients with urticaria, angioedema, asthma, and rhinitis: development of a radioallergosorbent test

A series of patients was identified who demonstrated immediate positive skin tests to intradermal Trichophyton extract. These skin responses did not correlate with other fungal skin tests and were present both in atopic and nonatopic patients. The individuals demonstrating positive immediate skin tests included patients with urticaria, angioedema, asthma, and/or rhinitis, as well as five of 34 normal control subjects. Most skin test positive individuals had a history of local fungal infection and clinical signs suggestive of fungal infection. By use of Trichophyton tonsurans extract linked to Sepharose as the immunosorbent, it was possible to measure IgE antibodies in 26/30 sera from skin test positive individuals. With strongly positive sera, RAST bound up to 30% of the radiolabeled anti-IgE added. The results confirm that most skin test positive individuals have IgE-mediated hypersensitivity to Trichophyton. These observations support the older view that absorption of dermatophyte allergen through the skin should be considered as a possible cause of allergic disease.     

ELISA in Diagnosis of Respiratory Allergy

An enzyme-linked immunosorbent assay (ELISA), employing beta-galactosidase conjugated anti-IgE, was used for the determination of specific IgE antibodies to common inhalant allergens (Dermatophagoides pt. and f., Parietaria and four grass pollens) in serum samples from 82 adult patients with asthma and/or rhinitis. A total of 194 analysis were carried out and the results were compared with those of skin tests and RAST. The correlation coefficient (r) between ELISA and RAST results was high (r = 0.95); the correlation between skin tests and ELISA (r = 0.93) was greater than that between skin tests and RAST (r = 0.90). No significant differences were found among the allergens used. We conclude that the version of ELISA used develops an overall good correlation with skin tests and RAST and seems to provide a satisfactory alternative to RAST for allergy diagnosis.     

Egg-white sensitivity and atopic eczema

Thirty-four children with atopic eczema were studied for egg-white sensitivity. Clinical manifestations, skin reactivity to egg-white antigen, IgE, by radioimmunoassay (RIA), and specific reaginic IgE antibodies to egg white by the radioallergosorbent test (RAST) were evaluated. Patients were divided into two groups on the basis of clinical sensitivity to egg-white antigen. Of 13 eczematous patients in Group I with known clinical egg sensitivity, 2 had RAST levels between 0 and 24 per cent, 6 between 25 and 100 per cent, and 5 had levels greater than 100 per cent. In this group, 5 had positive prick skin tests to egg white. Of 21 eczematous patients in Group II with no demonstrated clinical egg sensitivity, 17 had RAST levels of 0 to 24 per cent, 3 had RAST levels between 25 and 100 per cent, and one had an RAST level greater than 100 per cent. In this group, 3 had positive prick tests to egg white. The egg-white RAST showed a significant correlation with clinical egg sensitivity (p = 0.0005) and with a prick skin test of the same antigen (p = 0.036) but not with total serum IgE levels. However, no correlation was found between clinical egg sensitivity and egg-white prick skin test.     

The comparison of allergic responses to Dermatophagoides farinae between bronchial asthma and allergic rhinitis

The allergic responses of 52 bronchial asthma patients who exhibited a positive bronchoprovocation test with house dust and 50 allergic rhinitis patients who had positive RAST results to Dermatophagoides farinae (D. farinae) were studied, including the measurement of D. farinae-specific IgE using D. farinae-RAST, total IgE and skin reactivity to D. farinae and house dust. A comparison between the allergic rhinitis group in which methacholine PC20 was more than 4.66 mg/mL and the allergic rhinitis group which presented negative results in the methacholine bronchial challenge test, indicated that there were significant differences in skin test reactivity and the ratio of specific IgE to total IgE (P less than .05). The allergic responses we observed were not different between the allergic rhinitis group in which methacholine PC20 was less than 4.66 mg/mL (asthmatic range of methacholine PC20) and the allergic rhinitis group in which methacholine PC20 was more than 4.66 mg/mL. When comparing the bronchial asthma group which showed positive results in D. farinae-RAST and the allergic rhinitis group in which methacholine PC20 was less than 4.66 mg/mL, significant differences were noted in total IgE level (P less than .05). These findings suggest that the development of bronchial asthma in patients with allergic rhinitis might be predicted by measuring the degree of bronchial hyperreactivity and their allergic responses.     

Specific immunoglobulin E antibodies in tear secretions of patients with vernal conjunctivitis

Twenty-two patients with vernal conjunctivitis (VC) were studied by radioallergosorbent test (RAST) for specific IgE antibodies to the inhalant pollen allergens in tear secretions. Specific IgE antibodies were detected in the tear secretions of 12 (54.5%) patients with VC. Six patients had a positive tear RAST, but the corresponding serum RAST and immediate skin test reactivity were negative. The specific tear IgE antibodies appeared to correlate with the seasonal prevalence of the pollen in the environment and the period of maximal symptomatology. Six patients had both positive serum and tear RAST determinations. A double ratio formula with transferrin as a marker for the leakage of plasma proteins into tear secretions and the “specific activity” ratios of IgE antibody to total IgE between the tear secretions and the serum indicated that almost all (79% to 99%) of the tear IgE antibodies were locally produced. IgE antibodies were also detected in the tears of four of 10 patients with allergic conjunctivitis (AC) and of three with allergic rhinitis (AR). However, the “specific activity” ratio in the patients with AC and AR with measurable tear IgE suggested that the IgE antibodies were derived from the leakage of serum proteins into the tear secretions. These findings suggest that the pathogenesis of VC may be IgE mediated in some patients and lends support to the concept that specific IgE antibodies can be produced locally by the target organ, i.e., conjunctival tissues.     

Generalized allergic reactions during anesthesia.

Twenty-eight adults with a history of a generalized allergic reaction during anesthesia were investigated. The reactions were systemic in 23 adults, urticaria/angioedema in four, and bronchial obstruction in one adult. The study population and an additional 35 subjects with a history of use of thiopental during anesthesia but without reactions were investigated by methods including thiopental skin test, succinylcholine skin test, and IgE RAST for antibodies to thiopental, succinylcholine, or latex. Among the 28 patients with reactions, 17 had positive thiopental skin tests; 14/28 reactors and 1/35 of the control group had an IgE thiopental RAST value greater than 2 SD above the mean for control sera from ragweed-allergic subjects. The one control subject with a positive thiopental RAST also was the only control subject with a positive thiopental skin test. IgE succinylcholine RAST was negative in all 23 reactor sera tested. The IgE latex RAST was strongly positive in one reactor. In conclusion, evidence of allergy, particularly allergy to thiopental as a possible basis for the reactions, was obtained in greater than 50% of the patients who were investigated. No allergy to succinylcholine was found.     

Risk factors for latex allergy in patients with spina bifida and latex sensitization

BACKGROUND: Some subjects with spina bifida (SB) and latex sensitization (cutaneous and/or serum IgE) can have clinical reactions, while others may have no symptoms after the exposure to latex products. OBJECTIVE: This study was carried out to determine the risk factors associated with latex allergy in patients affected with SB and latex sensitization. METHODS: Fifty-nine consecutive subjects affected with SB, besides answering a questionnaire, underwent a skin-prick test (SPT) to latex and the determination of the specific serum IgE (RAST CAP) to latex. The total serum IgE concentration was determined and SPT to common aero- and food-allergens, skin tests (prick + prick) with fresh foods (kiwi, pear, orange, pineapple, tomato, banana) and RAST CAP to the same foods tested by the prick + prick technique, were also performed. RESULTS: Fifteen out of the 59 subjects (25%) were sensitized to latex according to the presence of IgE to latex detected by SPT (nine patients) and/or RAST CAP (13 patients). Five out of the 15 sensitized patients (33%) suffered from clinical reactions to latex (urticaria, conjunctivitis, angioedema, rhinitis, bronchial asthma) while they were using latex gloves and while inflating latex balloons. In the 15 sensitized patients, the presence of specific latex seric IgE > 3.5 kU/L (>/= class 3), a positive latex SPT, an elevated total serum IgE, and a positive prick + prick and/or a positive RAST CAP to foods, were significant (P < 0.05) risk factors associated with latex symptoms. The other factors tested (age, gender, months of intermittent bladder catheterization, surgical procedures, SPT reactivity and clinical reactions to aero-allergens and food-allergens, skin tests for fresh foods, positive RAST CAP to foods) were not significantly different in symptomatic and asymptomatic patients. CONCLUSION: Significant risk factors for symptoms to latex in patients with SB and latex sensitization were a presence of specific IgE to latex > 3.5 kU/L, a more frequent positive latex SPT, elevated total IgE, and one or more positive prick + prick and/or RAST CAP to fresh foods.     

Discrepancies between the skin test and IgE antibody assays: study of histamine release, complement activation in vitro, and occurrence of allergen-specific IgG

Intracutaneous skin tests (STs) and RAST with the common allergens, grass pollen, house dust mite, and cat dander, were performed on 660 adult patients. In 117 patients (18%), we found 140 discordances (7%) in a total number of 1980 ST and RAST combinations. In agreement with studies in the literature, greater than 80% of the discordances consisted of positive skin reactions without detectable allergen-specific IgE antibodies in serum. The percentages of discordant results were similar for the three allergens. Reproducibility of both the RAST and the ST was evaluated in the discordant group. Repetition of the routine RAST procedure elicited results similar to those in the first test in 81% (105/130). A second ST elicited identical results in 89% (47/53). In addition to the routine IgE antibody assay, sera of patients with a positive ST but without detectable IgE antibodies were tested in two other RAST systems: (1) a RAST with allergen extracts from the same production batch as the ST reagents, and (2) the Pharmacia RAST. In spite of having a clearly positive ST, sera from 68 (80%) of 85 patients remained completely negative in all three RAST systems. Histamine release (HR) in vitro from washed leukocytes was studied in 35 patients with a reproducible positive ST and negative RAST results with serum. Interpretation of this test was possible in 28 patients. In 82% (23/28) of these patients, clearly detectable HR was found with the relevant allergen extract. A role of IgE in the skin reactions and HR tests was confirmed by positive RAST results with IgE that was affinity purified from serum of seven of these patients. Allergen-specific IgG4 antibodies are unlikely to be implicated, since no antibodies against grass pollen and house dust mite were detectable in sera of these patients. Only 18% of the patients with an unexplained skin reaction with cat dander have detectable IgG4 antibodies, but these antibodies were found in a similar frequency in a nonallergic, ST negative control group. Low total IgG responses precluded false negative RAST results caused by competition of IgG antibodies with IgE antibodies. There were no significant differences in the degree of complement activation in vitro by house-dust extracts between healthy control subjects, nonallergic patients, and patients with unexplained skin reactivity. It is concluded that a high proportion of the positive skin reactions with common inhalant allergens, which are not accompanied by a positive RAST, are probably caused by IgE antibodies that are not detectable in serum with any of the RAST procedures.(ABSTRACT TRUNCATED AT 400 WORDS)     

Allergic rhinitis in Rosa domescena cultivators: a novel type of occupational allergy?

After the diagnosis of allergic rhinitis due to Rosa domescena was suspected in one subject with skin prick and nasal provocation tests, we recruited all other workers employed in rose cultivation in Yaka?ren village, Isparta. From May 2000 to July 2000 (exposure period 'time of rose handling'), we studied 600 individuals employed in rose cultivation. A questionnaire was administered by a physician, and skin testing was done by a nurse on 75 individuals suffering from asthma and/or rhinitis. Sera from these 75 subjects were available for immunologic testing. The diagnosis of atopy against rose was based on the presence of work-related symptoms, positive skin prick test (SPT) with rose extracts, and positive RAST. While no subject reported asthmatic symptoms, twenty of them reported either rhino-conjunctivitis, rhinitis or both on exposure to Rosa domescena. Fourteen of these subjects had increased specific IgE levels to Rosa domescena. Eleven (78.5%) also had a positive skin reaction to Rosa domescena. Out of the six negative sera with normal specific IgE levels to rose, only two (33.3%) had positive skin reactivity. No subject had significant daily peak expiratoy flow rate (PEFR) variations. We conclude that exposure to Rosa domescena may represent a risk for allergic rhinitis. The possibility of an occupational rose allergy should therefore be taken into consideration in the subjects working in rose cultivation.     

Specific serum IgE antibodies to bacterial antigens in allergic lung disease*

A radio-allergosorbent test (RAST) to measure specific IgE antibodies in man to whole bacterial cells of Streptococcus pneumoniae, Staphylococcasaureus and Haemophilus influenzae was developed to investigate different well-defined lung diseases (chronic bronchitis, allergic bronchopulmonary aspergillosis (ABPA), bronchial asthma, allergic rhinitis, cystic fibrosis) and also in urticaria as compared with non-atopic blood donors, in addition, total IgE values and skin prick tests were assessed in these patients. The ABPA group gave the highest specific IgE RAST scores to all three bacteria. whilst the chronic bronchitis and cystic fibrosis groups also gave raised RAST scores withH. influenzae. There was a positive correlation between the patients' Sta. aureus and Str. pneumoniae immediate-type skin reactions and their RAST scores and total serum IgE concentrations, but there was only a low incidence of immediate-type skin test positivity to H. influenzae.     

Intradermal skin tests with Dermatophagoides pteronyssinus in asthmatic children: correlation with specific IgE and bronchial provocation tests

The purpose of the present study was to compare the results of the skin tests, the specific IgE levels and bronchial provocation tests in a group of sensitive asthmatic children with a Dermatophagoides pteronyssinus extract standardized by the RAST inhibition method. Skin tests showed a positive ‘end point’ in twelve children of 0.5 U/ml antigen; in eleven 5 U/ml; seven of 50 U/ml; six of 500 U/ml. Specific IgE was present in thirty-three children (92%). A close relationship between positive skin tests and serum IgE levels was found. Bronchial provocation tests were positive in twenty-eight children (78%): eight children with both positive RAST and positive skin tests had negative bronchial provocation tests.     

Diagnosis of penicillin allergy by means of Phadebas RAST® penicilloyl G and V and skin tests

Fifty patients with suspected allergy to penicillin were tested. Skin tests were done with Na-penicillin G and penicilloyl-polylysin. Specific IgE antibody assays were done with penicilloyl G and V conjugates by means of RAST. The overall agreement between skin test and RAST results was 87%, borderline cases not included. In one case, skin tests were positive to penicillamine only, while RAST for penicilloyl G and V both proved to be positive. One case of penicillin allergy could be diagnosed in vitro post mortem only. Two cases of Hoigné syndrome showed no evidence of allergy. Patterns of skin manifestations varied but urticaria was the most commonly seen feature. Twenty patients without adverse reactions to penicillin treatment and seven patients who had not received penicillin over the last 10 years served as controls. None of them were positive in either skin tests or RAST. Two of our twenty control patients developed penicillin allergy during the study. Both showed positive RAST results.     

Prospective evaluation of chymopapain sensitivity in patients undergoing chemonucleolysis

Immediate anaphylactic reactions after intradiscal chymopapain (CP) injection may occur in 1% of patients undergoing chemonucleolysis (CN). Skin prick testing to CP (10 mg/ml), a prescreening history, and CP serum-specific IgE determinations by the RAST method were performed in order to identify patients presensitized to CP before CN. Follow-up repeat CP skin testing and serum-specific IgE were done 2 to 6 weeks after CN to detect CP IgE-mediated sensitization resulting from the injection. Three of 84 patients who exhibited positive skin tests to CP before CN did not receive CP injections. Only one of the three patients (33%) was detected with elevated CP serum-specific IgE before CN. No immediate severe anaphylactic reactions caused by CP injection were encountered in the remaining 81 patients with negative CP skin tests and RASTs before CN. Eight (10%) nonlife-threatening immediate and late reactions were associated with conversion from negative skin tests and RASTs before CN to positive skin tests or RASTs after CN. Overall, 19 of 52 (37%) patients who returned for follow-up testing developed cutaneous sensitization to CP after CN. Despite the fact that RAST values after CN in these patients were significantly higher (p less than 0.002) than those with negative skin tests after CN, the sensitivity of the RAST was only 72% for identifying patients who developed positive CP skin tests after CN. This study demonstrated that CP skin testing is essential for prescreening patients because it was more sensitive than RAST for identification of CP sensitivity both before and after CN. Late allergic reactions and cutaneous sensitization to CP were common sequelae of CN.