Food allergen (peanut)-specific TH2 clones generated from the peripheral blood of a patient with peanut allergy.

BACKGROUND: Increasing evidence indicates a prominent role of allergen-specific TH2 cells, with high IL-4 and IL-5 production and low interferon-gamma production, in the regulation of IgE and eosinophil production in allergic disorders. However, most studies have concentrated on T cells reactive with inhalation allergens, whereas little is known about the properties of food allergen-reactive T cells. OBJECTIVES: In this study we therefore characterized peanut-specific T cells, cloned from a patient with severe peanut allergy. METHODS: Peripheral blood mononuclear cells from patients with peanut allergy and nonallergic individuals were stimulated with crude peanut extract (CPE) to compare the proliferative responses and to select a suitable patient for the cloning of CPE-specific T cells. The resultant panel of CPE-reactive T-lymphocyte clones was serologically phenotyped by flow cytometry and analyzed for cytokine secretion by ELISA. RESULTS: The patients' peripheral blood mononuclear cells showed a dose-dependent proliferation response to CPE, which was significantly higher (p < 0.05) than in peripheral blood mononuclear cells of nonallergic donors. The CPE-specific T-lymphocyte clones generated from the selected patient were all CD4+/CD8- T helper cells with a TH2 cytokine profile, secreting high amounts of IL-4 and IL-5, but little or no interferon-gamma. CONCLUSIONS: This study demonstrates that peanut-specific T cells do occur in the peripheral blood of patients with peanut allergy and suggests an increased frequency of these T cells in patients compared with nonallergic control subjects. The CD4+ phenotype and the TH2 cytokine profile of the CPE-specific T-lymphocyte clones suggest a functional role of allergen-specific TH2 cells in the pathophysiology of food allergy, similar to the function of inhalation allergen-specific TH2 cells.

Masking foods for food challenge: practical aspects of masking foods for a double-blind, placebo-controlled food challenge.

In diagnosing a food allergy or food intolerance, a double-blind, placebo-controlled food challenge (DBPCFC) with the suspected food or food substance is the only method available for objective confirmation of an assumed relationship between a suspected agent and a complaint. When the use of capsules as a vehicle for DBPCFC with the suspected agent is not feasible, recipes have to be developed for masking the suspected food with another food. We describe demands and other aspects of the development of recipes for DBPCFC purposes. The taste, smell, color, and texture of the suspected agent have to be hidden in such a way that the patient cannot tell which of the two foods (the active food or the placebo food) contains the suspected agent. Once developed, the recipes have to be judged carefully to ensure that the foods do not contain ingredients other than the suspected agent that can possibly provoke complaints in the patient. Besides ordinary equipment such as cutlery, glasses, and dishes, the minimal equipment needed for preparing the recipes is an accurate balance. The more laborious a recipe is to make, the more equipment is needed. The development of recipes and the preparation of masked foods are time-consuming, which makes DBPCFC with masked foods difficult to perform in daily clinical practice. Performing a DBPCFC with masked foods in daily clinical practice can be a great challenge to the imagination and creativity of a dietitian.

Prevalence of food allergy and intolerance in the adult Dutch population.

The prevalence of food allergy and intolerance (FA/FI) was studied in a random sample (n = 1483) of the Dutch adult population. First, the self-reported FA/FI reactions were investigated by questionnaire. Subsequently, in a clinical follow-up study, it was determined in how many cases this self-reported FA/FI could be objectively confirmed by double-blind placebo-controlled food challenge. More than 10% of the population (12.4%) reported FA/FI to specific food(s). Of the 144 subjects potentially available for the clinical follow-up study, 73 completed the whole protocol. In 12 subjects FA/FI could be confirmed by double-blind placebo-controlled food challenge. This indicates a minimum prevalence of FA/FI in the population of 0.8% (12 of 1483). Assuming that FA/FI is equal among participants, nonparticipants, and dropouts, the prevalence of FA/FI in the Dutch adult population is estimated to be 2.4%. The food (ingredients) involved included pork, white wine, and menthol. Two persons reacted to additives. In three persons glucose intolerance was observed. However, these specific intolerances probably do not reflect the distribution in the general population because the study population formed an extremely heterogeneous group, both with regard to the offending foods and the symptoms. The majority of the subjects had no serious complaints that required medical advice. We conclude that there is a gap between self-reported FA/FI and FA/FI that can be objectively confirmed by double-blind placebo-controlled food challenge.

Chronic urticaria due to dental eugenol.

A case is reported of a patient with chronic urticaria. The correlation between the symptoms and dental treatment gave rise to the supposition that a root canal cement was causing the trouble. A causal relationship with eugenol, a cement constituent, could only be established through provocative oral ingestion. There is a high probability that the oral provocation tests to eugenol are relevant. Nevertheless, caution is needed when dealing with chronic urticaria.