Measurement of plasma histamine in patients with suspected food hypersensitivity.

Plasma histamine determinations were performed on 15 subjects with suspected food hypersensitivity following subcutaneous food provocation with milk, egg or wheat antigens. Significant rises in plasma histamine were observed in four of the 15 subjects tested; in these four subjects positive responses were seen with a total of five food test challenges. No changes were observed in total blood counts, differential eosinophil counts in six subjects and no correlation was observed with allergen-specific IgE responses. The results of these preliminary studies lend further support to the heterogeneity of causes of food allergy and suggest that the measurement of plasma histamine may provide an additional predictive marker for the diagnosis of food allergy. This technique permits the measurement of the ultimate mediator system(s) suspected to play a pathogenetic role in many food hypersensitivities.