Pathogenic role of thromboxane A2 in immediate food hypersensitivity reactions in children.

BACKGROUND: Food hypersensitivity, from the standpoint of pathogenesis as well as clinical management, remains controversial. During the food allergen-induced immediate hypersensitivity reaction, various chemical mediators are released. OBJECTIVE: The purpose of our study was to determine whether thromboxane A2 participates in food antigen-induced responses in children with food hypersensitivity. METHODS: Nine open food challenges were performed in nine patients with suspected food hypersensitivity. Plasma thromboxane B2 and histamine levels were measured during a 24-hour period following the challenge. RESULTS: All the patients demonstrated immediate reactions after food challenge. The mean plasma thromboxane B2 level (a marker of thromboxane A2 activity) rose significantly at two hours and three hours after the challenge. Simultaneously, the mean plasma histamine level rose significantly at two hours and three hours after the challenge. CONCLUSIONS: The results suggest that thromboxane A2 may play a pathogenic role in part in the immediate reaction after food challenge and that thromboxane A2 is probably released from a common cellular source (eg, mast cell) with histamine and/or by a common mechanism (eg, IgE-dependent platelet activation).

Time course of plasma histamine and tryptase following food challenges in children with suspected food allergy.

This study was undertaken to investigate the kinetics of histamine and tryptase in the circulation of patients with food allergy and to determine whether the measurements of plasma histamine and tryptase concentrations after food challenges provided additional predictive markers for the diagnosis and evaluation of food allergy. Twenty-one open food challenges were performed on 13 patients with suspected food allergy. Plasma histamine and tryptase concentrations were measured during 4 hours after challenge. In the group of patients with immediate reactions after challenges, the mean plasma histamine concentration rose significantly at 120 and 240 minutes after the challenge, and the mean plasma tryptase concentration was increased significantly at 240 minutes after challenge. Plasma histamine and tryptase concentrations were measured during 24 hours after 8 open food challenges in 7 other patients with suspected food allergy. In each patient with a nonimmediate reaction, plasma histamine concentrations were increased at the onset of symptoms after challenge, but no plasma tryptase concentrations increased. The elevation of plasma histamine and tryptase in patients with immediate reactions following food challenge indicates mast cell activation. On the other hand, the elevation of plasma histamine without elevated plasma tryptase in the patients with nonimmediate reactions following food challenge may indicate basophil activation rather than mast cell activation. Plasma histamine and tryptase measurements after food challenge may be useful in the detection and evaluation of food allergy.