Validation of inducible basophil biomarkers: Time, temperature and transportation.

BACKGROUND: The short stability window of several hours from blood collection to measuring basophil activation has limited the use of flow cytometry-based basophil activation assays in clinical settings. We examine if it is possible to extend this window to 1 day allowing for shipment of samples between laboratories. Several options exist for reporting the results including reporting all the measured values directly, calculating ratios and reporting a single value covering all measured results. Each of these options have different stability and value to the physician. METHODS: Whole blood samples from peanut allergic patients were stimulated with four different peanut concentrations at Day 0, Day 1, and Day 2. Samples were stored under temperature-controlled conditions. Flow cytometry was used to analyze the samples. The basophil activation and degranulation were measured as percentage of positive CD63 basophils and CD203c MFI fold change. Shipped samples were transported under ambient conditions. RESULTS: The results show that CD63 is a stable marker at Day 1. The CD203c ratio decreases significantly at Day 1. Calculating the CD63/IgE ratio proves to be more stable than CD63 alone. The most stable readouts are the semi-quantitative results and the trajectory of the dose response curve. Finally, we confirmed that the stability can be extended to samples shipped overnight to the laboratory. CONCLUSIONS: It is possible to extend the stability of the basophil activation assay to 1 day for samples stored at 18-25°C as well as samples shipped under ambient conditions as long as the temperature is within the 2-37°C range.

Perceived neighborhood safety and asthma morbidity in the school inner-city asthma study.

AIM: The aim of this study was to investigate whether neighborhood safety as perceived by primary caregivers is associated with asthma morbidity outcomes among inner-city school children with asthma. METHODS: School children with asthma were recruited from 25 inner-city schools between 2009 and 2012 for the School Inner-City Asthma Study (N = 219). Primary caregivers completed a baseline questionnaire detailing their perception of neighborhood safety and their children's asthma symptoms, and the children performed baseline pulmonary function tests. In this cross-sectional analysis, asthma control was compared between children whose caregivers perceived their neighborhood to be unsafe versus safe. RESULTS: After adjusting for potential confounders, those children whose primary caregivers perceived the neighborhood to be unsafe had twice the odds of having poorly controlled asthma (odds ratio [OR] adjusted = 2.2, 95% confidence interval [CI] = 1.2-3.9, P = 0.009), four times the odds of dyspnea and rescue medication use (OR adjusted = 4.7; 95% CI = 1.7-13.0, P = 0.003, OR adjusted = 4.0; 95% CI = 1.8-8.8, P < 0.001, respectively), three times as much limitation in activity (OR adjusted = 3.2; 95% CI = 1.4-7.7, P = 0.008), and more than twice the odds of night-time symptoms (OR adjusted = 2.2; 95% CI = 1.3-4.0, P = 0.007) compared to participants living in safe neighborhoods. There was no difference in pulmonary function test results between the two groups. CONCLUSIONS: Primary caregivers' perception of neighborhood safety is associated with childhood asthma morbidity among inner-city school children with asthma. Further study is needed to elucidate mechanisms behind this association, and future intervention studies to address social disadvantage may be important.

Allergens on desktop surfaces in preschools and elementary schools of urban children with asthma.

Desktop dust has been studied as a source of food allergen, but not as a source of potential aeroallergen exposure. Thirty-six wiped samples from desktop surfaces were collected from preschools and schools. Samples were analyzed for detectable levels of common aeroallergens including Alternaria, cockroach, dog, dust mite, cat, mouse, and rat allergens by immunoassay. Mouse allergen was the most prevalent, detectable in 97.2% of samples. Cat allergen was detectable in 80.6% of samples, and dog allergen was detectable in 77.8% of samples. Other allergens were not as prevalent. Mouse was the only allergen that was highly correlated with settled floor dust collected from the same rooms (r = 0.721, P < 0.001). This is the first study to detect aeroallergens on desktop surfaces by using moist wipes. Allergens for mouse, cat, and dog were highly detectable in wipes with mouse desktop surface levels correlating with levels in vacuumed floor dust.

Food allergy and increased asthma morbidity in a School-based Inner-City Asthma Study.

BACKGROUND: Children with asthma have increased prevalence of food allergies. The relationship between food allergy and asthma morbidity is unclear. OBJECTIVE: We aimed to investigate the presence of food allergy as an independent risk factor for increased asthma morbidity by using the School Inner-City Asthma Study, a prospective study that evaluates risk factors and asthma morbidity among urban children. METHODS: We prospectively surveyed, from inner-city schools, 300 children with physician-diagnosed asthma, followed by clinical evaluation. Food allergies were reported, which included symptoms experienced within 1 hour of food ingestion. Asthma morbidity, pulmonary function, and resource utilization were compared between children with food allergies and those without. RESULTS: Seventy-three of 300 children with asthma (24%) surveyed had physician-diagnosed food allergy, and 36 (12%) had multiple food allergies. Those with any food allergy independently had increased risk of hospitalization (OR [odds ratio] 2.35 [95% CI, 1.30-4.24]; P = .005) and use of controller medication (OR 1.99 [95% CI, 1.06-3.74]; P = .03). Those with multiple food allergies also had an independently higher risk of hospitalization in the past year (OR 4.10 [95% CI, 1.47-11.45]; P = .007), asthma-related hospitalization (OR 3.52 [95% CI, 1.12-11.03]; P = .03), controller medication use (OR 2.38 [95% CI, 1.00-5.66]; P = .05), and more provider visits (median, 4.5 vs 3.0; P = .008). Furthermore, lung function was significantly lower (percent predicted FEV1 and FEV1/FVC ratios) in both food allergy category groups. CONCLUSIONS: Food allergy is highly prevalent in inner-city school-aged children with asthma. Children with food allergies have increased asthma morbidity and health resource utilization with decreased lung function, and this association is stronger in those with multiple food allergies.

Predicting food challenge outcomes for baked milk: role of specific IgE and skin prick testing.

BACKGROUND: Cow's milk allergy is the most common food allergy in childhood. Many children with IgE-mediated cow's milk allergy may tolerate baked milk products, but few data exist on predictors of outcomes of baked milk challenges. OBJECTIVE: To determine the relation of milk protein allergen specific IgE (sIgE) levels and skin prick test (SPT) wheal size with baked milk challenge outcomes. METHODS: A retrospective medical record review was conducted of 35 baked milk challenges. SPT results, sIgE levels, demographic characteristics, and food challenge results were analyzed. RESULTS: Thirty-five children underwent open challenges to baked milk and 29 (83%) passed. Of those who failed, 3 (50%) passed the initial clinic challenge but developed symptoms to ongoing exposure at home, days to months later. One child who ultimately failed at home required epinephrine. Compared with those who passed, children who failed were younger (median age, 8.9 and 3.7 years, respectively; P = .02). Children with a milk SPT wheal less than 12 mm were more than 90% likely to pass a baked milk challenge, and no child with a milk SPT wheal less than 7 mm failed a baked milk challenge. We were also able to establish more than 90% predictive values for passing baked milk challenges with a casein SPT wheal of 9 mm, a milk sIgE level of 1.0 kU/L, and a casein sIgE level of 0.9 kU/L. CONCLUSION: Most children allergic to cow's milk tolerated baked milk. Milk protein SPT wheal may be more reliable than sIgE level in predicting outcomes of baked milk challenges. It is important to be aware of the possibility of late reactions to ongoing baked milk exposure.

Role of specific IgE and skin-prick testing in predicting food challenge results to baked egg.

Previous studies suggest that children with egg allergy may be able to tolerate baked egg. Reliable predictors of a successful baked egg challenge are not well established. We examined egg white-specific IgE levels, skin-prick test (SPT) results, and age as predictors of baked egg oral food challenge (OFC) outcomes. We conducted a retrospective chart review of children, aged 2-18 years, receiving an egg white-specific IgE level, SPT, and OFC to baked egg from 2008 to 2010. Fifty-two oral baked egg challenges were conducted. Of the 52 challenges, 83% (n = 43) passed and 17% (n = 9) failed, including 2 having anaphylaxis. Median SPT wheal size was 12 mm (range, 0-35 mm) for passed challenges and 17 mm (range, 10-30 mm) for failed challenges (p = 0.091). The negative predictive value for passing the OFC was 100% (9 of 9) if SPT wheal size was <10 mm. Median egg white-specific IgE was 2.02 kU/L (range, <0.35-13.00 kU/L) for passed challenges and 1.52 kU/L (range, 0.51-6.10 kU/L) for failed challenges (p = 0.660). Receiver operating characteristic (ROC) curve analysis for SPT revealed an area under the curve (AUC) of 0.64. ROC curve analysis for egg white-specific IgE revealed an AUC of 0.63. There was no significant difference in age between patients who failed and those who passed (median = 8.8 years versus 7.0 years; p = 0.721). Based on our sample, SPT, egg white-specific IgE and age are not good predictors of passing a baked egg challenge. However, there was a trend for more predictability with SPT wheal size.