Positive Prick Test Research Articles

Protein-contact eczematous reaction to cornstarch in clothing

Protein contact dermatitis is an eczematous reaction to antigens often associated with immediate hypersensitivity. A patient with a history of atopic eczema and multiple immediate sensitivities was seen for a persistent dermatitis of the face, hands, and clothing areas of the trunk and arms. Investigation showed a positive prick test to cornstarch, and avoidance of glove powder and starch in her clothing cleared what had been a recalcitrant problem. (J Am Acad Dermatol 1999;40:991-4.)

Facial dermatitis, contact urticaria, rhinoconjunctivitis, and asthma induced by potato

Background: Potato contains multiple heat-labile proteins which can induce immediate hypersensitivity reactions. Rhino-conjunctivitis, asthma, contact urticaria and protein contact dermatitis have been described in association with potato exposure. Objective: A patient with possible airborne facial dermatitis to potato is described. Results: A middle-aged atopic housewife with pre-existent atopic dermatitis suffered from rhino-conjunctivitis, asthma, and contact urticaria when pealing raw potatoes, but her main complaint was intense, treatment-resistant dermatitis of the face. The investigations showed a positive prick test, a positive patch test, and positive specific serum IgE to raw potato. Potato avoidance led not only to the resolution of the immediate symptoms, but also of the facial dermatitis, suggesting she had dermatitis due to this vegetable. Conclusions: Potato may induce contact dermatitis with positive immediate and delayed hypersensitivity tests.

Carob is not allergenic in peanut-allergic subjects.

The antigenic potential of proteins from the carob bean, a member of the legume family used as a food additive, have not so far been investigated and legumes share antigenic proteins with peanut, a potent trigger of anaphylaxis. To assess the carob protein determinants of sensitization in peanut-allergic children. In a prospective, double-blind, placebo-controlled study 12 patients (median age 9.5 years) with a history of hyperreactivity to peanut (anaphylaxis) were assessed. Skin prick tests with a commercial peanut allergen, raw carob pulp, raw and cooked carob cotyledon formula were used to confirm the history. RAST for peanuts and cooked carob were used to evaluate sensitization to these proteins. Carob-specific IgE were identified by immunoblotting analyses. Allergic reactivity was evaluated during double-blind placebo-controlled food challenges (DBPCFC; 5.5 g carob extract and cooked carob cotyledon formula). Peanut allergen-induced skin prick test positivity in all children (confirmed during double-blinded challenge in 6/12 patients), carob pulp in 3/12 patients, raw carob bean in 6/12, and cooked carob cotyledon formula in none. RAST were positive for peanut in all cases but negative for carob beans in 9/12 cases. Immunoblot analyses found peanut-specific IgE in all cases and raw carob bean-specific IgE in eight cases. Carob allergens were identified in the 17.5, 48, and 66 kDa MW bands. The least allergenic density was found for cooked carob proteins. There was no clinical reactivity with either raw or cooked carob during DBPCFC. These data suggest that carob-specific sensitization, apparent both in vitro and in SPTs, can be concordant with peanut allergy and that cooked carob can be ingested by children who are allergic to peanuts. That heat-processing deactivates carob protein allergenicity has dietary implications for polyallergic children.

Latex sensitization: occupational versus general population prevalence rates.

Natural rubber latex (NRL) has become an important occupational health concern in recent years, particularly among health care workers. It has been suggested in some reports that the prevalence of latex sensitization among occupationally exposed groups is not different from that in the general population. The findings of prevalence studies conducted among occupationally-exposed and general population groups were reviewed to determine whether there is evidence to support this suggestion. Numerous surveys of HCWs have demonstrated that the prevalence of sensitization to latex ranged in most studies from 5 to 12%; sensitization of HCWs may produce clinical effects including urticaria, rhinoconjunctivitis, occupational asthma, and potentially life-threatening anaphylactic shock. More than a decade ago, data from Finland indicated that the prevalence of latex allergy in the general population was less than 1%. Recent reports from Finland have confirmed this, with observations that 0.7-1.1% of large series of patients were NRL-allergic, while among 804 unselected patients, the prevalence of latex skin prick test (SPT) positivity was 0.12%. In contrast, other studies have suggested that from 4 to 6.4% of individuals tested were positive for serum latex-specific IgE antibodies. However, the specificity of these assays has been reported to be low. In three recent studies based on SPTs, published in 1997, the prevalence of positive reactions to latex was about 1% or less. The prevalence was 0.7% (95% CI 0.3-1.4) among 758 apprentices in Quebec, Canada; and 1.1% among more than 3,000 children tested in Finland (1.0% confirmed on latex use test). There were no first- and second-year dental students with positive latex SPTs in Ontario, Canada. These recent investigations provide further evidence consistent with earlier studies based on skin testing that the prevalence of latex sensitization in occupationally-unexposed groups is quite low (< 1%). The marked differences in the findings based on serological assays may relate to the nonspecificity of these assays and deserve further investigation.

PREVALENCE OF AND RISK FACTORS FOR LATEX SENSITIZATION IN PATIENTS WITH SPINA BIFIDA

Purpose We determined the prevalence of and risk factors for latex sensitization in patients with spina bifida. Materials and Methods A total of 59 consecutive subjects 2 to 40 years old with spina bifida answered a questionnaire, and underwent a latex skin prick test and determination of serum IgE specific for latex by RAST CAP radioimmunoassay. [sup *] We also noted the relationships of total serum IgE skin prick tests to common air and food allergens. In addition, skin prick plus prick tests were also done with fresh foods, including kiwi, pear, orange, almond, pineapple, apple, tomato and banana. Results Latex sensitization was present in 15 patients (25%) according to the presence of IgE specific to latex, as detected by a skin prick test in 9 and/or RAST CAP in 13. Five latex sensitized patients (33.3%) had clinical manifestations, such as urticaria, conjuctivitis, angioedema, rhinitis and bronchial asthma, while using a latex glove and inflating a latex balloon. Atopy was present in 21 patients (35.6%). In 14 patients (23%) 1 or more skin tests were positive for fresh foods using a prick plus prick technique. Tomato, kiwi, and pear were the most common skin test positive foods. Univariate analysis revealed that a history of 5 or more operations, atopy and positive prick plus prick tests results for pear and kiwi were significantly associated with latex sensitization. Multivariate analysis demonstrated that only atopy and a history of 5 or more operations were significantly and independently associated with latex sensitization. Conclusions A fourth of the patients with spina bifida were sensitized to latex. Atopy and an elevated number of operations were significant and independent predictors of latex sensitization in these cases.

THE PREDICTIVE VALUE OF PREEXISTING SPECIFIC ANTIBODIES TO APROTININ FOR ANAPHYLACTIC REACTIONS - A MULTICENTER STUDY IN 122 RE-EXPOSURES TO APROTININ

Aprotinin reduces bleeding tendency in cardiac surgery. Due to its protein nature it possesses antigenic properties. Allergic reactions during re-exposure to aprotinin have been described in casuistic reports [1]. The aim of the present study was to investigate the incidence of allergic reactions in drug re-exposure, the incidence of specific antibodies (AB), the predictive value of AB and of the exposure interval for the risk of anaphylactic reaction. Methods: With ethical approval and informed consent patients with re-exposure to aprotinin during redo open heart surgery were prospectively studied at five heart centers in Germany. Inclusion criterion for this observational study was a documented exposure to high dose aprotinin during a previous cardiac surgery. A preoperative prick test and a combined H1-/H2-receptor blockade during operation were part of the protocol. IgE and IgG AB were measured centrally in two institutions by sandwich ELISA and Uni-CAP or Western Blot, respectively, at the times: preoperatively, 5-7 days post op and in case of reaction at arrival in the ICU, 3 weeks and 3 months additionally. Results: 71 adult and 46 pediatric patients were included comprising 121 re-exposures (8x re-re-exposures). All pediatric patients were operated for correction or palliation of congenital heart disease, the adults for re-CABG (27), valve replacement (33), a combination of both procedures or other operations with HLM (12). (Table 1)Table 1None of the patients had a positive prick test. Adverse events differing in severety occurred in 3/121 exposures (2,5%). Two reacting patients were re-re-exposures. All of them have had their last exposure within a month period (22, 24 or 25 days). Four patients but none of the reacting ones died during their hospital stay. (Table 2)Table 2The diagnostic sensitivity of IgG measurement was 100%, the diagnostic specifity was 98% while the positive predictive value was 60%. Discussion: Relevant specific IgG levels before surgery and a short exposure interval [2] are of predictive value for an increased risk of allergic reaction. The incidence in re-exposure is 2,5%. The course of AB is time-dependent with great interindividual variation. Conclusion: Aprotinin should not be given within six months after previous treatment. If reexposure within this time is indicated preoperative measurement of IgG may identify patients at risk.

Oleaceae in Trieste (NE Italy): aerobiological and clinical data

Oleaceae pollen concentrations in the Trieste area are low (<10%) compared to the total number of airborne pollen grains, with only one pollination peak at the beginning of June when the Oleaceae concentration reached 62% of the total pollen count in 1992. This peak was due to an exceptionally high pollination of olive trees in 1992, when airborne pollen concentration rose to 1357 pollen grains/m3 on June 3. Sensitization toOlea increased from 1989 to 1993, when it was present in 23.4% of symptomatic patients, but the role ofOlea in inducing allergic respiratory symptoms is difficult to evaluate because almost all patients were sensitized to other pollens, and in particular to Gramineae: only four subjects were sensitized toOlea alone (1.4%). Despite the low Oleaceae pollen counts, this pollinosis is increasing, probably because of increased cultivation ofOlea in recent years. However, although skin prick test positivity is common in polysensitized patients, its role in inducing sensitization and symptoms is presently less important than that of other pollens.

Atopic dermatitis and food hypersensitivity reactions

Objective: To determine the role of food hypersensitivity in atopic dermatitis and to determine whether patients with atopic dermatitis who had food hypersensitivity could be identified by screening prick skin tests using a limited number of food allergens. Study design: Patients with atopic dermatitis attending the Arkansas Children's Hospital Pediatric Allergy Clinic underwent allergy prick skin testing to a battery of food antigens. Patients with positive prick skin tests underwent double-blind, placebo-controlled food challenges. Results: One-hundred sixty-five patients were enrolled and completed the study. Patients ranged in age from 4 months to 21.9 years (mean 48.9 months). Ninety-eight (60%) patients had at least one positive prick skin test. A total of 266 double-blind, placebo-controlled food challenges were performed. Sixty-four patients (38.7% of total) were interpreted as having a positive challenge. Seven foods (milk, egg, peanut, soy, wheat, cod/catfish, cashew) accounted for 89% of the positive challenges. By use of screening prick skin tests for these seven foods we could identify 99% of the food allergic patients correctly. Conclusions: This study confirms that most children with atopic dermatitis have food allergy that can be diagnosed by a prick skin test for the seven foods. (J Pediatr 1998;132:132-6)

Validation of a Self‐Administered Questionnaire on Asthmatic Symptoms and Atopy in House Painters

Validation of a Self‐Administered Questionnaire on Asthmatic Symptoms and Atopy in House Painters: Gunilla Wieslander, et ai. Department of Occupational and Environmental Medicine, Uppsala University—The aim of this study was to validate questions on asthmatic symptoms and atopy among Swedish house painters. Clinical investigations were performed in 44 male painters, selected by stratified sampling from a larger group of 415 painters. Symptoms were recorded by means of a self‐administered questionnaire. Clinical examinations were performed after an exposure free weekend, and included dermal prick test to nine common allergens, dynamic spirometry, and methacholine challenge test (MCT). Atopy was defined as at least one positive skin prick test to common allergens. A forced expiratory volume in one second (FEVd below 80% of normal values were considered a sign of impaired lung function. A cumulative dose of methacholine below 8 mg causing a 20% decrease in FEVt (PD20) was considered a sign of bronchial hyperresponsiveness (BHR). Sensitivity and specificity for different questions was calculated. Most single airway symptom had a good sensitivity for severe BHR, defined as a PD2o below 0.5 mg of methacholine. For milder BHR, however, sensitivity was below 50% for most single symptoms, except the question on nonspecific hyperreactivity symptoms. By combining the symptoms to a symptom score predicable of BHR, a high sensitivity could be obtained for both mild BHR and severe BHR. Most single questions on respiratory symptoms had high specificity, but low sensitivity, as predictors of impaired FEV‐,. Sensitivity for impaired FEV‐, was improved by constructing another symptom score, predictable of FEVt. The assessment of a history of atopy by five questions on asthma, hay fever and eczema in childhood was significantly related to atopy verified by a positive dermal prick test (79% sensitivity and 75% specificity). There was also a significant relation between self‐reported hay fever and positive prick test to pollen extracts (52% sensitivity and 90% specificity). In conclusion, our questions on airway symptoms and atopy are related to clinical signs of BHR, impaired FEV1# and atopy respectively. By combining different symptoms to symptom scores, the problem with low sensitivity of single questions on airway symptoms and atopy can be reduced.

Multiple food allergy: a possible diagnosis in breastfed infants.

Six infants suspected of food allergy during breastfeeding were evaluated using prick tests, total IgE, RASTs and intestinal permeability measurements during fast and provocation with mother's milk. An elimination diet was undertaken in mothers, removing first cow's milk protein (CMP), then, when inefficient, all foods suspected on the clinical history or a positive prick test in the child, followed by oral challenges in mother's diet with the corresponding food. The sole CMP-free diet in mothers always proved insufficient. In four, an additional diet excluding two to three other foods cleared the symptoms. Oral provocations in mother's diet with those foods were positive in all. In two, mothers turned down a diet excluding more than four foods, symptoms cleared while feeding the child with an extensively hydrolysed formula, whereas challenges with mother's milk induced immediate reactions. Intestinal permeability was altered during provocation tests with mother's milk sampled before maternal diet. Food allergy during breastfeeding may be due to multiple foods and the inefficacy of the sole CMP elimination in mothers does not rule out food sensitization.

Correlations between skin prick tests using commercial extracts and fresh foods, specific IgE, and food challenges.

The skin prick test is the most widely used test for detecting IgE-mediated food hypersensitivity. Our study aimed to define firstly the correlations between results obtained with prick tests using commercial extracts and fresh foods, and secondly the correlations between these results and those obtained with labial and/or oral challenge. We compared the wheal diameters read at 15 min with commercial extracts and fresh foods, for four foods, in 430 children with suspected food allergy. For cow's milk, wheal diameters were larger with commercial extracts, but the difference was not significant. Conversely, wheal diameters were significantly larger with fresh foods for the other food allergens. Skin prick tests were positive in 40% of cases with commercial extracts and in 81.3% with fresh foods. The overall concordance between a positive prick test and positive challenge was 58.8% with commercial extracts and 91.7% with fresh foods. These results indicate that fresh foods may be more effective for detecting the sensitivity to food allergens. Fresh foods should be used for primary testing for egg, peanut, and cow's milk sensitivity.

Socioeconomic status, number of siblings, and respiratory infections in early life as determinants of atopy in children.

Asthma and allergic disorders have been on the increase in recent decades, especially among children living in affluent countries; some aspects of the "Western" way of life may explain this trend. We evaluated the relation of aeroallergen skin test reactivity with socioeconomic status, number of siblings, and respiratory infections in early life. We examined a total of 2,226 schoolchildren, ages 7-11 years, in three areas of Lazio, Italy. Skin prick tests were performed to assess atopic status, and self-administered questionnaires were completed by the parents. The prevalence of prick test positivity was greater among children whose fathers were in the highest educational level than among those in the lowest [prevalence ratio (PR) = 1.58; 95% confidence interval (CI) = 1.21-2.06]. There was also a lower prevalence of atopy among larger sibships (PR = 0.38 for subjects with four or more siblings vs those without siblings; 95% CI = 0.14-0.99). A history of bronchitis or bronchiolitis before age 2 years was weakly associated with an increased risk of atopy, whereas a history of pertussis or pneumonia was not. Both the effect of father's education and the influence of larger sibship size remained when we adjusted for several potential confounding factors, including respiratory infections in early life. We infer that higher socioeconomic status and lower sibling number are determinants of atopy in this Italian population. Protection arising from early severe respiratory infections does not explain this association, although we cannot exclude a role for other viral infections.

Absence of genetic linkage of chromosome 5q31 with asthma and atopy in the general population.

BACKGROUND: Clinical asthma is associated with increased serum total immunoglobulin E (IgE), atopy (skin prick test positivity to common aeroallergens), and bronchial hyperreactivity (BHR) to non-specific stimuli (positive methacholine challenge...

Prévalence des manifestations cliniques évocatrices d'allergie au cours de l'infection par le VIH. Étude transversale de 115 sujets

A cross sectional survey was set up to study the relation between the prevalence of allergic-type reactions during HIV infection course. For each patient, a standardized interview about recent allergic-type manifestations (RATM), skin prick-tests to six common airborne allergens, IgE serum level were done. Among the 115 included patients, the mean CD4 lymphocyte count (CD4) was 214.7/mm3 (range: 0-1328/mm3). RATM were found in 8.8% of patients with CD4 < 50, in 30% of patients with CD4 between 51 and 200, in 36% of patients with CD4 between 201 and 350 and in 11.5% of patients with CD4 < 350 (p = 0.03). The risk of presenting RATM was 4.8 times (95% confidence interval = 1.7-13.5) higher in patients with CD4 between 51 and 350 than in other patients (p = 0.003). The proportion of positive prick-tests did not significantly vary according to the level of CD4. The increased frequency of RATM in patients with CD4 between 51 and 350/mm3 could be due to an allergic predisposition acquired during the course of HIV infection. The mechanisms explaining the reduced frequency of allergic manifestations when immunodeficiency is profound (CD4 < 50/mm3) remain to be explained.

Differences in skin‐prick and patch‐test reactivity are related to the heterogeneity of atopic eczema in infants

Current data indicate an obvious relation between food allergy and atopic eczema in infants. However, diagnostic methods for food allergy need to be supplemented. The objective was to study the relevance of food patch testing in the detection of food allergy in correlation with oral food challenge and skin prick tests in atopic infants. Infants with atopic eczema (n = 113) aged 2-24 months were studied. Each patient was subjected to double-blind, placebo-controlled, or open cow's milk challenge, and skin prick and patch tests. Polysensitization, as judged from skin test results, was common in patients with atopic eczema (79/113). Cow's milk challenge was positive in 54/113 infants; reactions were immediate in 36/54 and delayed in 18/54. Immediate-type reactions were associated with skin prick test positivity and delayed reactions with patch test positivity. Altogether 26% of the cow's milk-allergic infants were detected by patch testing only. Patch testing improved the accuracy of skin testing in the diagnosis of food allergy in infants with atopic eczema, but it needs to be standardized. Polysensitization appears to be more common than generally believed among infants with atopic eczema.

Mite-contaminated foods as a cause of anaphylaxis

Although insect and arthropod contamination of certain foods has been recognized for many years, allergic manifestations caused by ingestion of mite allergens have only rarely been reported. The purpose of this study is to present clinical observations in patients who experienced acute anaphylaxis after eating mite-contaminated foods. Thirty atopic subjects who were first seen with systemic anaphylaxis precipitated by the ingestion of wheat-containing foods underwent skin prick tests with inhalant and food extracts, as well as with uncontaminated and mite-contaminated wheat flour. Flour samples were examined microscopically for identification and counting of mites. Der p 1 and Der f 1 levels were quantitated by using immunochemical methods. The most common symptoms were breathlessness, angioedema, wheezing, and rhinorrhea, which started between 10 and 240 minutes after eating. Abundant mites were present in the flour obtained from 28 patients; Suidasia spp. mites were found in grated bread from the other two patients. Positive prick test responses to Dermatophagoides farinae-and mite-contaminated flour and negative skin test responses to wheat extract, other food extracts, and uncontaminated wheat flour were found in all patients. Skin test responses were positive in volunteers with mite allergy even after heating the mite-contaminated flour at 100 degrees C. Screening of 35 unselected flour samples demonstrated the presence of mites in 13 of them (37.1%). Systemic anaphylaxis can occur after the ingestion of heated or unheated mite-contaminated foods. This problem may be more prevalent in tropical and subtropical countries than previously recognized.

Anisakis simplex, a relevant etiologic factor in acute urticaria.

Anisakis simplex, a parasite of fish and cephalopods, can induce IgE-mediated reactions. This study aimed to determine the etiologic role of A. simplex in patients affected by urticaria/angioedema (AE) or anaphylaxis. We studied 100 adult subjects suffering acute episodes of urticaria/AE, by anamnesis, prick tests with A. simplex and fish-mix extracts, and total and specific IgE to both A. simplex and cod. The following criteria of A. simplex allergy were considered: 1) urticaria/AE within 6 h after fish ingestion; 2) specific IgE to A. simplex; 3) positive prick test to A. simplex extract; 4) exclusion of other suspected causes. Double-blind, placebo-controlled food challenge was not carried out because ethical considerations forbid challenge with a parasite. Specific IgE to A. simplex (> 0.7 kU/l) was found in 22 subjects, but only eight were diagnosed as having A. simplex allergy. Other allergens were involved in 37 patients, and 55 cases were considered idiopathic. Specific IgE to fish (> 0.7 kU/l) was found in two patients, but only one was diagnosed as having fish allergy. We concluded that A. simplex is an important etiologic factor in acute urticaria. We suggest that it should be considered in cases of urticaria/AE or anaphylaxis, especially after fish ingestion.

Maternal smoking during pregnancy and lactation increases the risk for atopic eczema in the offspring

Background: Maternal smoking during pregnancy has been shown to lead to immunologic changes in the offspring. However, little is known about the influence of this exposure on atopic manifestations. Objective: Our purpose was to investigate the influence of air pollutants on manifestations of atopy in preschool children. Methods: Unselected cohorts of a total of 678 5- to 6-year-old preschool children (350 boys, 328 girls) were investigated in areas with different degrees of air pollution in Bavaria. Data on the history of atopic diseases and other relevant factors were obtained by questionnaire. A skin-prick test was performed with common aeroallergens. Manifestation of atopy was defined as personal history of atopic disease or positive prick test to either grass pollen, house dust mite, or cat and analyzed multivariately. Results: Of all children, 38.9% exhibited at least one manifestation of atopy. Atopic eczema was reported in 7.9% to 15.5%, hayfever in 4.1% to 25.6%, and asthma in 3.0% to 8.1%. Of the mothers, 12.6% smoked during pregnancy or lactation or both. Analysis of the manifestation of atopy including sex, location, nitrogen oxide and sulfur dioxide exposure and maternal smoking as covariates revealed an influence of the maternal smoking during pregnancy/lactation. Of children whose mothers had smoked during pregnancy/lactation, 52.2% exhibited manifestations of atopy in contrast to 35.7% of children of nonsmoking mothers ( p < 0.044). A history of atopic eczema was the only component of the variable "manifestation of atopy" that was significantly associated with maternal smoking during pregnancy and lactation. A causal interpretation of this finding, however, was not supported by a follow-up study. Conclusion: Maternal smoking during pregnancy or lactation or both might play a role in the development of atopic eczema and should be avoided. (J Am Acad Dermatol 1997;36:550-6.)

Latex sensitivity in dental students and staff: A cross-sectional study

Background: Dental practitioners, like other health care providers who regularly use latex gloves, are at increased risk for latex sensitivity. They are also at risk for irritant or allergic contact dermatitis. Objective: This study was carried out to determine the prevalence of latex sensitivity and possible risk factors in staff and students of a Faculty of Dentistry. Methods: A cross-sectional study was performed by using a questionnaire and allergy skin prick testing. Results: Two hundred three students and staff members completed the questionnaire. Five percent reported asthma symptoms on exposure to rubber products, 13% reported symptoms of rhinitis or conjunctivitis, and 17% reported pruritus or urticaria within minutes of exposure to rubber. Overall, 10% of 131 subjects who underwent skin prick tests had a positive response to natural rubber latex. Among the students tested, there were increasing percentages of positive skin test responses to latex with increasing years of study (0% of Year 1 and 2 students tested; 6% of Year 3; and 10% of Year 4). Positive responses were seen as early as Year 3 in students (in their second year of clinical activity and glove use). Positive skin prick test responses to latex were related to a personal history of atopy ( p = 0.005), positive prick test responses to common allergens ( p < 0.005), latex-attributed immediate pruritus or urticaria ( p < 0.05), rhinoconjunctivitis ( p < 0.001), and asthma symptoms ( p < 0.001). Conclusion: Dental school students and faculty are at high risk for latex sensitization. This occurs as early as the second year of glove use. Overall prevalence of skin sensitization was 10% of those tested. Preventive strategies in this group merit further investigation.(J Allergy Clin Immunol 1997;99:396–401.)

Childhood antecedents of allergic sensitization in young British adults

Objective: This study was designed to investigate whether associations of self-reported hay fever with sibship size, birth order, infant feeding, and childhood socioeconomic status reflect variations in sensitization to common aeroallergens. Methods: One thousand three hundred sixty-nine persons born throughout Britain in 1958 were followed up to age 34 to 35 years. The cohort included 1050 subjects with a history of asthma, wheezy bronchitis, wheezing, or pneumonia and 319 with no history of wheezing illness at ages 7, 11, 16, 23, or 33 years. Skin prick tests with extracts of mixed grass pollen, house dust mite (Der p 1), and cat fur were performed; and wheal diameters were measured. Results: The prevalence of positive skin test results (≥3 mm wheal) was independently related ( p < 0.01) to male sex, reduced numbers of older siblings (but not younger siblings), and higher socioeconomic status in childhood. Current cigarette smoking and maternal smoking during pregnancy were independently associated ( p < 0.01) with a reduced prevalence of skin prick test positivity. No significant independent effects ( p > 0.10) were found for adult social class, maternal age, birth weight, gestation, breast feeding, preschool nursery attendance, urban birthplace, or gas stove exposure. Conclusion: Factors related to small families and relative affluence in childhood promote atopic sensitization to a variety of aeroallergens in later life. These observations are consistent with the suggestion that early infection may protect against subsequent allergic disease. (J Allergy Clin Immunol 1997;99-6-12.)