Oral food challenges in children

Food Allergy a Constant Concern to the Medical World and Healthcare Providers: Practical Aspects

Food allergy (FA) is a condition with a growing incidence and is a constant concern for the medical world and healthcare providers. With potential symptoms including anaphylaxis, in the event of an allergic reaction the patient’s life may well be endangered. The diagnosis of FA is a continuous challenge because mild cases tend to be ignored or diagnosed late and young children with allergies are cared for by parents, who are not always able to accurately interpret symptoms. It is very important to be able to differentiate FAs from food intolerance and toxic reactions to food. An accurate diagnosis is required to provide personalized management of an FA. More sophisticated and accurate diagnostic tests, including component diagnosis and epitope reactivity, allow the provision of a directed diagnosis, a more accurate therapeutic approach, and a useful prognostic evaluation. Tests used in current practice include the specific search for serum IgE, elimination diets, oral food challenges, single, blind, and double-blind (DBPCFC) tests, as well as skin tests. The risk of anaphylaxis can be assessed by molecular diagnostics/component-resolved diagnosis (CRD) and by conducting a basophilic activation test (BAT). These tests allow a planned, personalized treatment based on molecular and clinical profiles. CRD can determine the individual profile of allergic molecular reactivity and enable the formulation of a prognostic judgment. Our article highlights the importance of knowing the immune mechanisms, diagnostics, and immunotherapies in FAs. Starting from observing exposure to food allergens, to identifying allergic reactions, analysing the severity of clinical manifestations, noting the possibilities of diagnosis, and illustrating adequate management strategies.

Eosinophil-Derived Neurotoxin, Tumor Necrosis Factor Alpha, and Calprotectin as Non-Invasive Biomarkers of Food Protein-Induced Allergic Proctocolitis in Infants

Diagnosis of non-IgE mediated food allergy presents a special challenge due to lack of a single, non-invasive diagnostic method. We selected three fecal biomarkers of allergic inflammation of gastrointestinal origin in order to improve the diagnostic process. Twenty-seven infants with symptoms of hematochezia were prospectively enrolled into this study. All patients underwent a complete differential diagnosis of rectal bleeding. Non-IgE mediated food allergy was confirmed by an open, oral food challenge. The control group included twenty-five infants with functional gastrointestinal disorders. Eosinophil-derived neurotoxin (EDN), tumor necrosis factor alpha (TNFα), and calprotectin concentration were measured in stools of all children by enzyme-linked immunosorbent assays (ELISA) using commercial kits. Median eosinophil-derived neurotoxin and calprotectin fecal levels were significantly higher in the study group than in the control group (p < 0.05). The difference of fecal tumor necrosis factor alpha concentration between both groups was not statistically significant (p > 0.05). The best diagnostic performance was reached in a combination of fecal calprotectin (fCal) and EDN i.e., 88.9% and 84%, respectively. Fecal EDN and fCAl are reliable tools in differentiating between food protein-induced allergic proctocolitis and gastrointestinal functional disorders in infants.

Impact of Food Immunoglobulin G-Based Elimination Diet on Subsequent Food Immunoglobulin G and Quality of Life in Overweight/Obese Adults

OBJECTIVES

The goal of this study was to assess changes in serum immunoglobulin G (IgG) food antibody titers and quality-of-life measurements following a targeted elimination diet in overweight/obese adults.

METHODS

We performed a randomized control trial. Participants were randomized in a 2:1 ratio to either an intervention group or waitlist group for 3 months. Food IgG testing was performed on all participants. The intervention group was instructed to eliminate up to 10 foods, for which they had high titers of IgG and communicated with health coaches for nutritional counseling for meal planning and adherence. The waitlist group did not receive their IgG testing results or health coaching. Primary outcome was serum IgG titers for foods eliminated during the trial, compared with baseline concentrations. Secondary outcomes were health-related quality of life measured by Patient-Reported Outcomes Measurement Information System (PROMIS-29) and change in participant-identified symptom severity measured by Measure Yourself Medical Outcome Profile. Exploratory outcomes were changes in body weight and waist circumference.

RESULTS

IgG antibody concentrations decreased in 83% of the targeted foods in the treatment group and in 60% of the foods in the waitlist group, but this was not found to be a statistically significant difference. The intervention group reported improvement in sleep during the trial compared with waitlist, which was the only statistically significant finding in the study.

CONCLUSIONS

The findings are consistent with changes in IgG titer measurements following an elimination diet based on IgG testing. Future larger clinical trials are necessary to determine the degree to which these findings are generalizable.

Diagnostic Decision Points of Specific IgE Concentrations in Korean Children With Egg and Cow's Milk Allergies

Purpose

The purpose of this study was to evaluate the utility of specific IgE (sIgE) concentrations for the diagnosis of immediate-type egg and cow's milk (CM) allergies in Korean children and to determine the optimal cutoff levels.

Methods

In this prospective study, children ≥12 months of age with suspected egg or CM allergy were enrolled. Food allergy was diagnosed by an open oral food challenge (OFC) or through the presence of a convincing history after ingestion of egg or CM. The cutoff levels of sIgE for egg white (EW) and CM were determined by analyzing the receiver operating characteristic curves.

Results

Out of 273 children, 52 (19.0%) were confirmed to have egg allergy. CM allergy was found in 52 (23.1%) of 225 children. The EW-sIgE concentration indicating a positive predictive value (PPV) of >90% was 28.1 kU/L in children <24 months of age and 22.9 kU/L in those ≥24 months of age. For CM-sIgE, the concentration of 31.4 kU/L in children <24 months of age and 10.1 kU/L in those ≥24 months of age indicated a >90% PPV. EW-sIgE levels of 3.45 kU/L presented a negative predictive value (NPV) of 93.6% in children <24 months of age, while 1.80 kU/L in those ≥24 months of age presented a NPV of 99.2%. The CM-sIgE levels of 0.59 kU/L in children <24 months of age and 0.94 kU/L in those ≥24 months of age showed NPVs of 100% and 96.9%.

Conclusions

Our results indicate that different diagnostic decision points (DDPs) of sIgE levels should be used for the diagnosis of egg or CM allergy in Korean children. The data also suggest that DDPs with high PPV and high NPV are useful for determining whether OFC is required in children with suspected egg or CM allergy.

Tropomyosin sensitization in house dust mite allergic patients

The growing popularity and frequency of consumption of seafood is accompanied by an increasing number of adverse reactions reported in literature. Allergic reactions to seafood can generate a variety of symptoms ranging from a mild oral allergy syndrome to keen anaphylactic reactions. Tropomyosin, the major shellfish allergen is regarded to be responsible for clinical cross-reactivity to inhaled house dust mites. The aim of the study was to investigate the prevalence of sensitization to tropomyosin in house dust mite allergic patients in southern Bavaria and to compare the results with allergic symptoms. Sera of house dust mite allergic patients (positive skin prick test, allergen-specific IgE and intranasal provocation) were screened for IgE antibodies to tropomyosin (Der p 10). Patients were contacted by phone to evaluate allergic symptoms when consuming seafood. IgE antibodies to house dust mite tropomyosin (Der p 10) could be found in 4 out of 93 sera (4.3%). Two of these four patients (50%) showed itching and swelling of oral mucosa accompanied by bronchial obstruction after consumption of shrimp. Two patients had no problems when eating seafood. None of the seronegative patients complained about any health problems during or after consumption of seafood. In conclusion, cross-reactivity to tropomyosin in house dust mite allergic patients in southern Bavaria, Germany is rarer than suspected. Beside the direct allergic reactions, a further part of reactions to seafood must therefore be ascribed to other mechanisms such as intoxication or intolerance to, e.g. additives in the food product.

End point prick test: could this new test be used to predict the outcome of oral food challenge in children with cow's milk allergy?

Background

Cow's milk allergy (CMA) is the most frequent food allergy in childhood; the trend of CMA is often characterized by a progressive improvement to achieve tolerance in the first 4 to 5 years of life.

It has been observed that specific IgE (sIgE) towards cow's milk proteins decrease when the age increases.

Although food allergy can be easily diagnosed, it is difficult to predict the outcome of the oral food challenge (OFC), that remains the gold standard in the diagnosis of food allergy, by allergometric tests.

Methods

We considered 44 children with CMA diagnosed through OFC who returned to our Allergy and Immunology Pediatric Department between January to December 2010 to evaluate the persistence of allergy or the achievement of tolerance.

On the basis of the history, we performed both allergometric skin tests and OFC in children that were still following a milk-free diet, whereas only allergometric skin tests those that had already undergone spontaneous introduction of milk protein at home without presenting symptoms.

Objective

The aim of this study was to investigate the relationship between the persistence of CMA or the acquisition of tolerance and the results of the end point prick test (EPT).

Results and Discussion

The OFC with cow's milk was performed on 30 children, 4 children were excluded because of a history of severe reactions to cow's milk, and 10 because they had spontaneously already taken milk food derivates at home without problems. 16/30 (53%) children showed clinical reactions and the challenge was stopped, 14/30 (47%) did not have any reaction.

Comparing the mean wheal diameter of every EPT's dilution between the group of allergic children and the tolerant ones, we obtained a significant difference (p < 0.05) for the first 4 dilutions.

We have also calculated sensitivity (SE), specificity (SP), the positive predictive value (PPV) and the negative predictive value (NPV) for each EPT dilution.

Conclusions

EPT is a safe and cheap test, easy to be executed and that could provide good prediction of the outcome of OFC; so it might be used to avoid OFC-induced anaphylaxis in children affected by CMA. It can also help avoiding dietetic restrictions in tolerant children who show sensitization towards cow's milk proteins.