N.-I. M. Kjellman

Serum IgE levels in healthy children quantified by a sandwich technique (PRIST

Serum IgE was estimated in 226 healthy children aged 0–14 years without obvious atopic disease in their first degree relatives. A paper disc radioimmunoassay technique (PRIST) was used. A number of criteria for selection of cases were established. This led to the exclusion of forty‐two potentially atopic children. The remaining group of 184 children is considered representative of normal children and may therefore be used for reference purposes. The IgE levels were found to be lower than in previous investigations, and this is attributed to the refined technique and the method of selection.

Effect of maternal avoidance of eggs, cow's milk and fish during lactation upon allergic manifestations in infants

Atopic/allergic manifestations and skin‐prick tests (SPT) to egg white, cows milk (CM) and fish were evaluated during the first 18 months of life in two matched groups of infants with a family history of atopy/allergy. In one group (n= 65) the mothers had a diet free from eggs, CM and fish during the first 3 months postpartum, whereas the mothers in the other group (n= 50) consumed an ordinary diet. The diet of the infants was similar in both groups, i.e. CM was not supplied until 6 months of age, and eggs and fish not until 9 months of age. The incidence of atopic dermatitis was significantly lower in the maternal diet group during the first 6 months postpartum (10.8 and 28%, respectively) but not after that age. Other atopic/allergic manifestations did not differ and the number of positive SPT to egg white, CM or fish at 9 months of age was similar in both groups.

Appearance of atopic disease in relation to serum IgE antibodies in children followed up from birth for 4 to 15 years

BACKGROUND Few studies have addressed the relationship between sensitization and the development of atopic disease over many years. OBJECTIVE To study the temporal relationship between the appearance of IgE antibodies in serum and atopic disease, we studied 324 children from three different groups, who were followed up prospectively from birth for 4, 12, and 15 years, respectively. METHODS Serum samples were obtained at various ages and analyzed for IgE antibodies against egg white, cows milk, wheat, animal dander, house dust mite, birch and timothy with Phadebas RAST (Kabi Pharmacia Diagnostics AB, Uppsala, Sweden) or Pharmacia CAP system. In addition, a screening test for atopy, the Phadiatop Paediatric test (Kabi Pharmacia Diagnostics AB) was performed. Presence of atopic disease was assessed by means of clinical examination, interviews, and questionnaires. RESULTS In 135 children IgE antibodies were detected at least once to at least one allergen. Antibodies to egg white appeared in 46 children before or at 2 years of age: in 57% of them IgE antibodies to inhalants developed within the next 2 years, and in 19 of 25 (76%) IgE antibodies to inhalants developed before or at 12 to 15 years. Antibodies to inhalant allergens appeared in 55 children during the first 4 years of life and in 64 before 12 to 15 years. Among the former 48% and among the latter 32% had previously detectable egg white antibodies. Atopic disease appeared before or at age 4 years in 80% of the 40 children with IgE antibodies against egg white up to 9 months of age and in 69% of the 58 children who had a positive Phadiatop Paediatric test result in infancy. CONCLUSIONS IgE antibodies in children are usually associated with current or later topic disease. Sensitization to foods in infants is usually associated with appearance of IgE antibodies to inhalants later in life.

Comparison of IgE values as determined by different solid phase radioimmunoassay methods.

Accurate measurement of low IgE concentrations is technically difficult. In this paper results obtained by a direct sandwich and three inhibition methods of radioimmunoassays are compared. For values above 50 U/ml good correlation was obtained with all methods. Below 50 U/ml, however, the inhibition methods tended to yield falsely high values. For very low concentrations, 1–10 U/ml the best correlation was obtained between the direct sandwich test (PRIST*) and the inhibition test using a correction factor to allow for the non‐specific effect of serum.

Atopy among schoolchildren in northern and southern Sweden in relation to pet ownership and early life events.

Studies have suggested a higher prevalence of asthma and allergies in northern, as compared to southern, Scandinavia. The aim of this study was to evaluate regional differences in atopy in relation to pet ownership and certain early life events among schoolchildren (n = 2108) aged 10–11 years from Linköping in southern Sweden and Östersund in northern Sweden. The parents completed a questionnaire, comprising questions on home environment, heredity, socio‐economic conditions, and the core questions on symptoms from the International Study of Asthma and Allergies in Childhood. The children were skin‐prick tested to eight common inhalant allergens. Information on maternal smoking habits, gestational age, and anthropometric measures were obtained from the Swedish Medical Birth Registry. The prevalence of atopic symptoms and sensitization to pollen were similar in Östersund and in Linköping. A higher prevalence of sensitization to animal dander among children in Östersund could be linked to a higher occurrence of pets in the community. Current cat ownership was related to less sensitivity to cat allergen but only in children with an atopic heredity. Ponderal index > 30 kg/m3 was related to an increased risk of atopic sensitization, both in Linköping (adjusted odds ratio 2.1; 95% confidence interval 1.1–4.0) and in Östersund (adjusted odds ratio 2.0; 95% confidence interval 1.1–3.5). Maternal smoking during pregnancy was related to an increased risk of atopic sensitization among children in Linköping, whereas current smoking was associated with a decreased risk of sensitization in Östersund. In conclusion, we demonstrated that a high occurrence of pets in the community was associated with sensitization, whereas atopic symptoms were essentially unaffected. This study has also suggested an association between body size at birth and atopic sensitization at 10–11 years of age.

Peripheral blood eosinophilia in infants at 3 months of age is associated with subsequent development of atopic disease in early childhood

BACKGROUND We tested the hypothesis that eosinophilia in peripheral blood and nasal mucosa of infants is an early sign of allergic disease. METHODS The appearance of eosinophilic leukocytes in peripheral blood and nasal mucosa was studied prospectively in 67 infants up to 18 months of age, with or without a family history of atopy. RESULTS Eosinophilia was associated with simultaneous presence or subsequent development of atopic disease at 3, 9, and 18 months of age, but not significantly so at 6 months. At 3 months children in whom atopic disease developed later during the observation period had significantly higher numbers of blood eosinophils than children without atopy (p < 0.01). Thus pronounced eosinophilia (> 7 x 10(8) cells/L) at that age was associated with moderate or severe allergic disease during the 18-month observation period. These children continued to have eosinophilia throughout the follow-up period. Blood eosinophilia at 3 months of age also correlated significantly to cord blood IgE levels and to skin prick test reactivity later during the follow-up period. Nasal eosinophilia was a common finding and therefore had little diagnostic or predictive value. CONCLUSIONS Elevated eosinophil counts in peripheral blood of apparently healthy infants at 3 months of age is associated with a subsequent diagnosis of atopic disease.

Pertussis IgE and atopic disease

Background Pertussis toxin (PT) stimulates IgE production in animals, and pertussis vaccination and whooping cough may have similar effects in man. Methods We analyzed IgE responses to PT (FT‐IgE) in sera from children primarily immunized with three doses of either an acellular 2‐ or 5‐component vaccine, or a whole‐cell (We) pertussis vaccine, and in children after whooping cough. The study comprised 50 children with both atopic disease and positive skin prick test, 99 nonatopic controls, and 40 children with verified pertussis.

Hypertonic saline challenge tests in the diagnosis of bronchial hyperresponsiveness and asthma in children

The hypertonic saline challenge test is the recommended method to assess bronchial hyperresponsiveness in the International Study of Asthma and Allergies in Childhood (ISAAC). The sensitivity of this procedure to assess asthma symptoms, however, has been reported to vary among study centers. The purpose of our study was to evaluate the value of this provocation test in an epidemiological survey in children, and to relate the degree of bronchial hyperresponsiveness to the severity of asthma symptoms. All 11–13‐year‐old children from 16 randomly selected schools in Linköping, Sweden received a questionnaire regarding respiratory symptoms and allergic disease. Skin prick tests with eight inhalant allergens were performed. In addition, all children with wheeze over the past 12 months (current wheeze) and a random sample of children without current wheeze were invited to perform hypertonic saline provocation tests. A complete data set was available for 170 children, including 50 with and 120 without current wheeze. Bronchial hyperresponsiveness (BHR) was defined as at least 15% decline in FEV1. The degree of BHR was represented by the response/dose ratio, i.e. the fall in FEV1 divided by total dose of inhaled saline. The severity of asthma symptoms was classified by the number of wheezing episodes over the past 12 months. ‘Asthma ever’ was defined by a combination of symptoms in the questionnaires. Children with ‘asthma ever’ and current wheeze were considered as having current asthma. Current atopic asthma was defined as current asthma with at least one positive skin prick test. The sensitivity of the procedure to detect ‘asthma ever’, current asthma and current atopic asthma was 62, 61 and 83%, and the specificity 83, 81 and 60%, respectively. The positive challenge rate was 52, 34, 13 and 7% among current wheezers, previous wheezers, non‐wheezers with a history of allergy and healthy children. The degree of bronchial hyperresponsiveness increased with the number of wheezing episodes. Thus, the median and range of the response/dose ratio were 4.8%/ml (2.1–14.8), 2.6%/ml (0.7–8.6) and 1.3%/ml (0.8–2.7), respectively, for children with ≥ 4 episodes, 1–3 episodes and no wheezing episodes over the past 12 months (p<0.001). In conclusion, hypertonic saline provocation test is useful as a tool to detect asthma in epidemiological studies in children. The degree of bronchial hyperresponsiveness, as represented by the response/dose ratio, reflects the severity of asthma symptoms.

High anti‐IgE levels at birth are associated with a reduced allergy prevalence in infants at risk: a prospective study

Development of atopic disease was prospectively studied in 148 children from birth to the age of 18 months and related to serum levels of IgG anti‐IgE antibody. Children with a dual heredity of allergy, but remaining healthy, had significantly higher IgG anti‐IgE levels at birth than children with a similar predisposition to allergy, who became allergic. Children with increased allergy risk, defined by elevated IgE levels at birth (>= 0.53 kU/l) and with probable allergy symptoms had also significantly higher IgG anti‐IgE levels at birth than children of the same risk group, developing definite allergy. Independent of allergy risk, there was a significantly lower prevalence of atopic disease in children with cord serum levels of IgG anti‐IgE above 350AU.1 than in children with lower levels. Additionally, we showed that the allergy predictive capacity of IgE levels in cord serum was slightly improved in specificity, sensitivity and efficiency by including not only the family history of allergy, but also cord serum levels of IgG anti‐IgE. Our results thus raise the possibility that high levels of IgG anti‐IgE protect children of increased allergy risk from early development of atopic disease and reduce the severity of symptoms.

Predictive value of serum IgE levels during rush hyposensitization

Thirty children with hay fever were studied with in vivo and in vitro tests during rush hyposensitization with Timothy pollen. Clinical assessment was made with the aid of diaries during one season before, and three seasons after, the start of the immunotherapy. When the serum level of IgE increased more than 10% during the first week of the therapy, symptoms were mostly alleviated during the following seasons. An alleviation was rarely found in children with decreasing or unchanged serum IgE levels. No predictive information as to the clinical effect of the immunotherapy was obtained from skin or provocation tests, nor from Timothy‐specific antibodies of the IgG or IgE classes. It is proposed that serum IgE determinations should be performed before, and 1 week after, the start of rush hyposensitization in order to find probable therapeutic failures.