An evaluation of spontaneous histamine release and the low responders in a basophil histamine release test

Background: We evaluated the clinical significance of the spontaneous histamine release ratio (SHR/T) and low responders in the automated basophil histamine release test (Allerport® HRT). Methods: This study analyzed the outcomes of 101 oral food challenges (OFC) with egg, milk or wheat (challenge-positive: n=79) in relation to the SHR/T. The traditional HRT low responders (n=27) were separated into two groups: "LOW" responders (n=10), who showed a ≥10% concentration-dependent maximum histamine release in response to the anti-human IgE stimulation, and "NON" responders who did not fulfill the criteria (n=17). Results: Among the 34 patients with ≥20% SHR/T, 32 patients (94%) had a positive OFC with a low threshold dose which provoked severe symptoms. Among the "LOW" responders, four cases showed ≥10% allergen-specific maximum histamine release. On the other hand, concentration-dependent histamine release was not seen in the "NON" responders, suggesting the basophil function was not detected in this subgroup. Conclusion: The present study suggested that SHR/T could be an indicator of basophil activation and hypersensitivity in vivo. We also suggested that significant basophil functions might be detected among the "LOW" responders, but not among the "NON" responders.