Allergen-specific
immunoglobulin E (
IgE) reactions lead to acute degranulation of mast cells and basophils and release of stored mediators, particularly
tryptase and
histamine, which can be measured in vitro after reactions. The aim of this study was to investigate the utility of serum
tryptase and plasma
histamine during oral food challenge (OFC) in 103 children with suspected
food allergy, in order to support the diagnosis of a
IgE-mediated reaction. Blood samples for serum
tryptase and plasma
histamine were collected before the OFC and after the onset of allergic symptoms or after 60 minutes from test completion. Serum
tryptase and plasma
histamine were measured by a fluoroenzyme immunoassay (ImmunoCAP; ThermoFisher, Uppsala, Sweden) according to the manufacturers instructions. A correlation between serum
tryptase and plasma
histamine distributions was observed after OFC (p=0.0035). A correlation was also observed for both serum
tryptase and plasma
histamine before and after OFC (p less than0.0001). Subjects with positive response to OFC had significantly higher values (p = 0.0375) of serum
tryptase compared to subjects with negative response. The plasma
histamine distribution showed a significant difference between measurements before and after OFC, both in the complete population (p less than 0.0001), and considering the response (negative OFC: p less than 0.0001; positive OFC: p=0.0181). The diagnostic work-up of
IgE- mediated
food allergy may include determination of serum
tryptase and plasma
histamine, in order to support the results of OFC. These markers are strongly related to the same
IgE-mediated mechanism and, as they can be both easily measured, can confirm the allergic nature of a reaction in the real-life setting of
food allergy.