Bimodal skin reactivity to histamine in atopic children in Singapore: influence of specific sensitizations

Protocol for a prospective multicenter cross-sectional observational study to investigate the role of air pollution on allergic rhinitis prevalence

INTRODUCTION

Allergic rhinitis (AR) is a major chronic inflammatory disease of the respiratory tract. A large number of epidemiological investigations have shown that the prevalence of AR is increasing, resulting in a large social burden. Importantly, the impact of air pollution on health is a widespread concern. We aim to evaluate association of air pollution and AR risk.

METHODS AND ANALYSIS

This prospective study includes patients undergoing AR. The exclusion criteria will be as follows: Patients with nasal infection, nasal polyps, nasal tumors, mental disorders, and immunodeficiency will be excluded. Air pollution levels of ambient air pollutants including PM2.5, PM10, sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon dioxide (CO), and O3, and patient data will be collected. The correlation analysis will be performed in air pollutants and AR risk.

DISCUSSION

This study will provide correlation of NO2, SO2, PM10, and PM2.5 for AR in several aspects, including symptom score, drug score, quality of life score, asthma control score, side effects, and laboratory examination such as nasal function test, serum total immunoglobulin E, and nasal secretion smear.

Allergy and inhibitors in hemophilia - a rare complication with potential novel solutions

INTRODUCTION

Hemophilia is a rare bleeding disorder caused by a deficiency of the plasma coagulation factors VIII and IX (hemophilia A [HA] and hemophilia B [HB], respectively). Replacement therapy with clotting factor concentrates is the mainstay of treatment. Unlike in patients with HB, anaphylaxis in patients with HA is extremely rare.

METHODS

A retrospective study of prospectively collected data on patients with hemophilia who experienced anaphylaxis was conducted in our center. Demographic and clinical data were collected, and laboratory workups that included thrombin generation were conducted.

RESULTS

Our first patient underwent successful immune tolerance induction (ITI) following the administration of rituximab. The second patient was transitioned to emicizumab. The third patient receives recombinant activated VIIa (rFVIIa) on demand. Thrombin generation was performed following current medical management protocols for supporting hemostasis.

DISCUSSION

Our case series illustrates the difficulty in managing patients with anaphylaxis to replacement therapy. In the era of novel therapies, such as emicizumab, the management of HA patients who experience anaphylaxis to replacement therapy is becoming easier and may obviate the need for ITI. Current treatment strategies for HB patients with such anaphylaxis, however, are limited to rFVIIa, and it continues to pose a challenge.

Association of body mass index and season with histamine skin reactivity in Chinese children with allergic rhinitis

BACKGROUND

To investigate the association between histamine skin reactivity and body mass index (BMI) and other clinical factors, 526 children (3-6 years old) who underwent a skin-prick test (SPT) to diagnose allergic rhinitis were enrolled.

METHODS

The SPT was carried out using 43 common allergens (commercial kit). The wheal size was analyzed. The associations between histamine reactivity and age, gender, BMI, atopy, parental smoking history, and testing season were examined.

RESULTS

Mean age was 4.6 ± 1.1 years. Among all 526 children, 202 (38.4%) had intermittent allergic rhinitis (IAR), 164 (32.1%) had IAR + persistent allergic rhinitis (PER), and 160 (30.4%) had PER. The size of the histamine skin wheal and maximum diameter for positive allergens showed significant seasonal differences (P = 0.001 and P = 0.02, respectively). Children with biparental allergy history had a higher BMI (P = 0.006). BMI (P < 0.001), summer testing (P = 0.001), and autumn testing (P < 0.001) were independently associated with the size of the histamine skin wheal. Only winter testing was independently associated with the maximal diameter for positive allergens (P = 0.002).

CONCLUSIONS

Higher histamine skin reactivity was associated with higher BMI and summer or autumn testing. Subject BMI and season should be considered for better interpretation of the SPT. The mechanisms underlying these associations require further study.

Measurement and interpretation of skin prick test results

BACKGROUND

There are several methods to read skin prick test results in type-I allergy testing. A commonly used method is to characterize the wheal size by its 'average diameter'. A more accurate method is to scan the area of the wheal to calculate the actual size. In both methods, skin prick test (SPT) results can be corrected for histamine-sensitivity of the skin by dividing the results of the allergic reaction by the histamine control. The objectives of this study are to compare different techniques of quantifying SPT results, to determine a cut-off value for a positive SPT for histamine equivalent prick -index (HEP) area, and to study the accuracy of predicting cashew nut reactions in double-blind placebo-controlled food challenge (DBPCFC) tests with the different SPT methods.

METHODS

Data of 172 children with cashew nut sensitisation were used for the analysis. All patients underwent a DBPCFC with cashew nut. Per patient, the average diameter and scanned area of the wheal size were recorded. In addition, the same data for the histamine-induced wheal were collected for each patient. The accuracy in predicting the outcome of the DBPCFC using four different SPT readings (i.e. average diameter, area, HEP-index diameter, HEP-index area) were compared in a Receiver-Operating Characteristic (ROC) plot.

RESULTS

Characterizing the wheal size by the average diameter method is inaccurate compared to scanning method. A wheal average diameter of 3 mm is generally considered as a positive SPT cut-off value and an equivalent HEP-index area cut-off value of 0.4 was calculated. The four SPT methods yielded a comparable area under the curve (AUC) of 0.84, 0.85, 0.83 and 0.83, respectively. The four methods showed comparable accuracy in predicting cashew nut reactions in a DBPCFC.

CONCLUSIONS

The 'scanned area method' is theoretically more accurate in determining the wheal area than the 'average diameter method' and is recommended in academic research. A HEP-index area of 0.4 is determined as cut-off value for a positive SPT. However, in clinical practice, the 'average diameter method' is also useful, because this method provides similar accuracy in predicting cashew nut allergic reactions in the DBPCFC.

TRIAL REGISTRATION

Trial number NTR3572.

Evaluation of the applicability of the Immuno-solid-phase allergen chip (ISAC) assay in atopic patients in Singapore

Background/Objective

Molecular-based allergy diagnostics are gaining popularity in clinical practice. Our aim was to evaluate their role in the tropics, given the inherent genetic and environmental differences.

Methods

We recruited subjects with history of atopy and collected data on demographics and atopic symptoms using validated questionnaires. Subjects underwent a series of skin prick tests (SPT). Serum total and specific IgE levels were measured using ImmunoCAP FEIA and ImmunoCAP ISAC®, respectively. We describe their pattern of sensitization and agreement between test methods.

Results

A total of 135 subjects were recruited; mean ± SD age of 31.18 ± 12.72 years, 52.7% female. Allergic rhinitis (AR) was the most prevalent clinical manifestation of atopy (70.7%), followed by atopic dermatitis (AD) (50.5%) and asthma (26.2%). Polysensitization was seen in 51.1% of subjects by both SPT and ISAC. House dust mites (HDM) were the dominant allergen, with sensitization in 67.8% and 62% of subjects on SPT and ISAC, respectively. A group of subjects with monosensitization to B. tropicalis was identified. HDM sensitization was strongly associated with AR, while AD and asthma were not associated with sensitization to any allergen. Agreement between SPT and ISAC was mostly suboptimal. Greatest agreement was documented for the measurement of HDM sensitization with both methods (κ = 0.64). Sensitization to the bulk of the remaining allergens in the ISAC panel was infrequent.

Conclusion

Multiplex methods should not be used as a screening tool, especially in a population with lower rates of polysensitization and a dominant sensitizing allergen. There may be a role in adjusting the antigen spectrum in the ISAC panel to regional differences.

Electronic supplementary material

The online version of this article (doi:10.1186/s13601-015-0053-z) contains supplementary material, which is available to authorized users.

Histamine skin reactivity increases with body mass index in Korean children

OBJECTIVE

Histamine skin prick testing is most commonly used to diagnose immunoglobulin E (IgE)-mediated allergic diseases, and histamine reactivity is used as a standardized positive control in the interpretation of a skin prick test. However, reactivity to histamine differs among individuals for reasons that are poorly understood. The present study aimed to evaluate the potential association between body mass index (BMI) and histamine skin reactivity in children.

METHODS

A total of 451 children (246 boys, 205 girls) aged 7-8 years were enrolled in this study. The skin prick test was performed with 26 aeroallergens commonly found in Korea. Other information was collected, including sex, age, BMI, parental allergy history, and parental smoking status. Multivariate analysis was used to confirm the association between histamine skin reactivity and BMI.

RESULTS

The histamine wheal size was revealed to be associated with BMI (Spearman's Rho 0.161, p<0.001). This association was confirmed by multivariate analysis, after adjusting for sex, age, parental allergy history, parental smoking status, and allergic sensitization (coefficient B 0.071, 95% confidence interval 0.030-0.112).

CONCLUSIONS

Skin responses to histamine were primarily correlated with increased BMI. Further studies are needed to understand the clinical implication of BMI when interpreting the results of skin prick test.

The changing face of food hypersensitivity in an Asian community

BACKGROUND

Food allergy seems to be increasing in Asia as well as world-wide. Our aim was to characterize food protein sensitization patterns in a population of Asian children with possible food allergy.

METHODS

Children presenting to our allergy clinic over 3 years with symptomatic allergic disease and at least one specific food allergen sensitization documented on skin prick testing were included in the analysis.

RESULTS

Two hundred and twenty-seven patients fulfilled inclusion criteria. Ninety (40%) of the positive skin tests were positive to egg, 87 (39%) to shellfish, 62 (27.3%) to peanut, 30 (13.2%) to fish, 27 (11.8%) to cow's milk, 21 (9.3%) to sesame, 13 (3.7%) to wheat and eight (3.2%) to soy. Peanut sensitization was the third most common sensitizing allergen, and seen mostly in young atopic children with multiple food hypersensitivities and a family history of atopic dermatitis. The median reported age of first exposure to fish and shellfish was 6 and 12 months, respectively. The mean age at presentation of children with shellfish hypersensitivity was at 6.7 years of age. The likelihood of shellfish sensitization was increased in children with concomitant sensitization to cockroaches.

CONCLUSIONS

In contrast to previously reported low peanut allergy rates in Asia, in our review, peanut sensitization is present in 27% (62/227) of food-allergic children, mostly in patients with multiple food protein sensitizations. Temporal patterns of first exposure of infants to fish and shellfish are unique to the Asian diet. Shellfish are a major sensitizing food source in Asian children, especially in allergic rhinitis patients sensitized to cockroaches.

The influence of atopic status and potential risk factors for sensitization on histamine skin reactivity in unselected Belgian children

The histamine skin response is widely used as a standardized positive control in the performance of skin prick testing. As a part of the Aalst Allergy Study, we investigated whether histamine skin reactivity, using histamine 10 mg/mL, was influenced by age, gender, ethnic origin, environmental exposure, specific sensitization patterns, or other factors. The parents of 2021 nonselected children aged 3.4-14.8 years completed a baseline questionnaire and gave written informed consent for skin prick testing with seven common aeroallergens on their child. Sensitized children had significantly larger histamine wheal sizes than nonsensitized children (mean 4.3 vs 4.0 mm, p < 0.05). A significant difference was found in histamine wheal size between nonsensitized versus multiply sensitized children (p < 0.001), but not between mono-sensitized versus multiply sensitized children (p = 0.105). The only other factors associated with significantly larger histamine wheal sizes were a history of eczema and a history suggestive for asthma on the Brief Pediatric Asthma Screen Plus. The histamine wheal was absent in 8.9% of children. In conclusion, sensitization and some other clinical indicators of atopy were associated with a larger histamine skin wheal. Other conditions including gender and environmental exposure did not have an influence on histamine skin reactivity, which strengthens the use of histamine as a reference in skin prick testing in this age group.