A preceding airway reaction to one allergen may lead to priming of the airway responses to another allergen
Department of Pediatrics, Seoul National University Children's Hospital, Korea. Allergy
(Impact Factor: 6.03).
This study aimed to determine whether a preceding airway response to one allergen leads to priming of the airway responses to another allergen. Twelve asthmatic children who had positive prick tests to two allergens, Dermatophagoides pteronyssinus (D.p.) and German cockroach (CR), participated in a randomized, placebo-controlled crossover study. We performed two consecutive inhalation challenges, D.p. challenge being followed 48 h later by CR challenge. The effect of initial (D.p.) challenge on the early and late airway responses to the subsequent (CR) challenge (CR2) was examined by comparing the responses with those to CR challenge preceded by sham challenge (CR1). The geometric mean PD20 of CR allergen in the CR2 was 2.8 BU (breath unit) (range of 1 SD; 0.77-10.4), which was 12.0-fold less than that (33.7 BU, 10.8-105.2) in the CR1. The administration of a 6.1-fold less dose (8.9 BU, 2.7-28.8) in the CR2 than in the CR1 (54.5 BU, 44.1-69.3) provoked a similar degree of late-phase reactions (18.7 +/- 7.3% vs 15.8 +/- 9.6%). Our data indicated that the early- and late-phase reactions to CR challenge were augmented by the preceding reaction to D.p. This suggests that a preceding airway response to one allergen may lead to priming, with enhancement of the early and late airway responses to the subsequent challenge with another allergen.
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ABSTRACT: Bronchial asthma is characterized by airway inflammation, which underlies the phenomenon of bronchial hyperresponsiveness. Previous studies have shown that this correlates with the serum concentration of haptoglobin. The occurrence of the late asthmatic response (LAR) after an allergen challenge test is associated with airway inflammation. The objectives of this study were to examine serum levels of haptoglobin during the 24 h after allergen challenge and to compare changes between the subjects with and without LAR. We studied two groups of children with perennial asthma who developed the early asthmatic response (EAR) only (group I: n = 14), and EAR but also LAR (group II: n = 14) after an allergen (Dermatophagoides pteronyssinus) challenge test. Serum concentrations of haptoglobin were measured at baseline, at EAR, and at 2 h (recovery), 8 h (LAR), and 24 h after the challenge. Baseline levels were similar in the two groups (group I: 128 +/- 57 mg/dl; group II: 129 +/- 50 mg/dl). In group I, there was no significant change in the level at any time point; in contrast, the subjects in group II showed a relative fall (92 +/- 40 mg/dl) at 8 h, and an increase (161 +/- 79 mg/dl) at 24 h after the challenge. Our results indicate that the serum concentration of haptoglobin decreases at the time of LAR and is subsequently replenished during the ensuing time. Although further studies are needed, we think that haptoglobin may be inflused into the airways during the inflammatory process associated with LAR, and that this may be followed by "overshooting" production.
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ABSTRACT: The determinants of late asthmatic responses to exercise remain unknown. It has been reported that they may develop in some adult subjects with asthma following a late asthmatic response to allergen.
We intended to corroborate this finding in children with asthma and to investigate which aspect of airway responses to allergen is associated with late asthmatic responses to exercise.
We studied 17 children with allergic asthma, who showed late asthmatic responses to inhaled allergen (Dermatophagoides pteronyssinus). Each underwent an exercise challenge test two days before (pre-allergen) and two days after (postallergen) an allergen inhalation challenge. FEV1 was measured at regular intervals up to ten hours after each challenge. Methacholine PC20 was measured before the allergen challenge and before the postallergen exercise challenge.
After the pre-allergen exercise test, all the subjects showed isolated early asthmatic responses. After the postallergen exercise test, seven showed dual responses (early and late asthmatic responses) (group I) and the remaining ten showed isolated early asthmatic responses (group II). Bronchial responses to pre-allergen exercise or inhaled allergen and the severity of early asthmatic responses to postallergen exercise were similar in groups I and II. Neither before allergen inhalation nor before the postallergen exercise was methacholine PC20 different between the two groups. Methacholine dose shift caused by allergen challenge, however, was significantly greater in group I than in group II (-2.00+/-0.39 versus -1.36+/-0.53 doubling doses; P < .05). There was significant correlation between the dose shift and the magnitude of late response to the postallergen exercise in the whole group (r = 0.51, P < .05).
Late asthmatic responses to exercise may develop in some children with asthma following a late asthmatic response to allergen. This phenomenon was related neither to the baseline nor to postallergen methacholine PC20 but to the extent of increased sensitivity to methacholine caused by allergen challenge.
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ABSTRACT: Several longitudinal studies report that allergic sensitization increases with age from childhood to adulthood.
To evaluate whether an age-dependent tendency to become sensitized to new classes of allergens is present in atopic children, we studied retrospectively the changes in allergic sensitization in 165 asthmatic patients, monosensitized (ie, sensitized to only one class of allergens) in the first survey.
All the children (18 months to 8 years at enrollment), attended our outpatient clinics twice, at time intervals ranging from 2 to 10 years. On each visit, sensitization to house dust mites, pollens, animal danders, and molds was determined by skin prick test.
We found that 43.6% (n = 72) of the patients became polysensitized on the second survey. According to age on first survey, the patients were further divided into two age groups: (1) group 1 = 18 months to < 5 years old (n = 98) and (2) group 2 = 5 to 8 years (n = 67). The transition from monosensitization to polysensitization observed in the entire population was present in both groups: 47 (47.9%) of the 98 children in group 1 and 25 (37.3%) of the 67 children in group 2 showed to be sensitized to more classes of allergens, as compared with first survey. Both in the whole population and in the two age subgroups, the changes in the frequency of monosensitization between the two evaluations were time-dependent (P < .05, each Chi(2)). Finally, to investigate whether monosensitization to a specific class of allergens could favor the development of polysensitization, we evaluated the frequency of polysensitization in the second survey in patients originally monosensitized to house dust mites or to pollens. We found that of the 130 patients originally monosensitized to house dust mites, 59 became polysensitized (45.4%), while of the 28 patients originally monosensitized to pollens, 9 became polysensitized (32.1%) (P > . 1). Similar results were obtained when patients were divided into age groups.
These data demonstrate that (1) monosensitized children are likely to become polysensitized and (2) house dust mite sensitization and, at a lower degree, pollen sensitization, apparently seem to play a "triggering" role in the development of polysensitization, since a high proportion of children originally monosensitized to house dust mites or to pollens became polysensitized.
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