A subset of walnut allergic adults is sensitized to walnut 11S globulin Jug r 4.

BACKGROUND: The role of sensitization to commercially available allergens of English walnut (Juglans regia) Jug r 1, 2 and 3 in walnut allergy has been previously investigated in walnut allergic adults and was unable to explain all cases of walnut allergy. OBJECTIVES: Identify recognized walnut allergens, other than the ones previously investigated (Jug r 1-3), in walnut allergic adults and determine the sensitization frequency and diagnostic value. METHODS: Three different in-house walnut extracts were prepared and analysed on SDS-PAGE blots to identify allergenic walnut proteins. Immunoblots and immunoprecipitation, followed by LC-MS analysis, were performed to screen for, and confirm, IgE binding to walnut allergens in selected walnut allergic adults. In a cohort of 55 walnut challenged adults, including 33 allergic and 22 tolerant, sensitization to native and recombinant walnut allergen Jug r 4 was assessed using immunoblotting and immuno-line blot (EUROLINE), respectively. RESULTS: Screening of sera of 8 walnut allergic adults identified Jug r 4 as an allergen in our population. In the total cohort of 55 subjects, 5 were positive for Jug r 4 on immunoblot and 10 on EUROLINE. All but one EUROLINE positive subject had a positive food challenge (sensitivity 27%, specificity 95%, PPV 90%, NPV 47%). All 5 subjects positive on immunoblot were also positive on EUROLINE. LC-MS analysis showed a lack of Jug r 4 in the ImmunoCAP extract. Co-sensitization to other 11S albumins (eg hazelnut Cor a 9) was common in Jug r 4 sensitized subjects, potentially due to cross-reactivity. CONCLUSIONS: Walnut 11S globulin Jug r 4 is a relevant minor allergen, recognized by 27% of walnut allergic adults. It has a high positive predictive value of 90% for walnut allergy. Specific IgE against Jug r 4 occurred mostly with concomitant sensitization to other walnut components, mainly Jug r 1.

Assessing food allergy risks from residual peanut protein in highly refined vegetable oil.

Refined vegetable oils including refined peanut oil are widely used in foods. Due to shared production processes, refined non-peanut vegetable oils can contain residual peanut proteins. We estimated the predicted number of allergic reactions to residual peanut proteins using probabilistic risk assessment applied to several scenarios involving food products made with vegetable oils. Variables considered were: a) the estimated production scale of refined peanut oil, b) estimated cross-contact between refined vegetable oils during production, c) the proportion of fat in representative food products and d) the peanut protein concentration in refined peanut oil. For all products examined the predicted risk of objective allergic reactions in peanut-allergic users of the food products was extremely low. The number of predicted reactions ranged depending on the model from a high of 3 per 1000 eating occasions (Weibull) to no reactions (LogNormal). Significantly, all reactions were predicted for allergen intakes well below the amounts reported for the most sensitive individual described in the clinical literature. We conclude that the health risk from cross-contact between vegetable oils and refined peanut oil is negligible. None of the food products would warrant precautionary labelling for peanut according to the VITAL® programme of the Allergen Bureau.

A cell-based screening assay for Natural Killer cell activity.

Natural Killer (NK) cells are important in the first response against viruses and tumours. Compounds that modulate human NK cell activity offer interesting prophylactic and therapeutic options, however, a systematic screening tool is lacking. Development of suitable NK cell lines or receptor-based assays is hindered by the highly complicated regulation of the different NK cell subsets by multiple receptors. Here, we describe a cell-based flowcytometric activity assay adapted to identify NK cell modulating compounds. Fresh human peripheral blood mononuclear cells (PBMC) were incubated with NK-sensitive K562 target cells labelled with 5-(6)-carboxyfluorescein succinimidyl ester, followed by DNA-labelling with propidium iodide to identify dead cells. The assay demonstrated a good performance with an average Z'-factor of 0.6 and over 95% of the assays fulfilled the quality criteria, suggesting that it is possible to use a complex system with two different cell types to screen compounds. A large number of (natural) compounds and extracts were tested and normalized to the positive control, Interleukin-2. Promising and less promising compounds were distinguished. Effectiveness of compounds was based on the augmentation of NK cell activity as well as the number of responding subjects. To conclude the assay is robust, reliable and can be used for functional screening of natural compounds modulating NK cell activity.

Treatment of inborn errors of urea synthesis: activation of alternative pathways of waste nitrogen synthesis and excretion.

Children with inborn errors of urea synthesis accumulate ammonium and other nitrogenous precursors of urea, leading to episodic coma and a high mortality rate. We used alternative pathways for the excretion of waste nitrogen as substitutes for the defective ureagenic pathways in 26 infants. These pathways involve synthesis and excretion of hippurate after sodium benzoate administration, and of citrulline and argininosuccinate after arginine supplementation. The children were treated for seven to 62 months; 22 survived. The mean plasma level of ammonium ( +/- S.E.) was 36 +/- 2 mumol per liter, and that of benzoate was 1.5 +/- 1.0 mg per deciliter. Alternative pathways accounted for between 28 and 59 per cent of the total "effective" excretion of waste nitrogen. Nineteen infants had normal height, weight, and head circumference, and 13 had normal intellectual development. Activation of alternative pathways of waste nitrogen excretion can prolong survival and improve clinical outcome in children with inborn errors of urea synthesis.