Blood Stored In EDTA Tubes Provides Accurate Peanut Basophil Activation Test Results For 48 hours.

BACKGROUND: The peanut basophil activation test (BAT) has demonstrated excellent diagnostic accuracy with heparinized blood, but its clinical utility is limited by the short stability of samples stored in this anticoagulant.

OBJECTIVE: Using EDTA anticoagulated blood, these investigations determined if Peanut BAT sample stability can be extended to 2 days, the minimum stability requirement for diagnostic tests currently offered through American reference laboratories.

METHODS: Peanut non-allergic control (NAC), peanut IgE sensitized (PS), and peanut allergic (PA) children aged 6 months through 17 years were recruited from members of Kaiser Permanente Southern California. EDTA anti-coagulated blood samples were collected from participants, shipped to a centralized laboratory, and stored at 4oC for peanut BAT testing 1 and 2 days later.

RESULTS: Peanut BAT results for 23 unblinded participants were used to establish sample rejection and interpretation criteria that were subsequently validated in a prospective double-blind study involving 112 additional children (39-NAC, 36-PS, 37-PA). Of 105 blinded blood samples tested on each study day, 88 (84%) day-1 and 90 (86%) day-2 peanut BAT results were considered interpretable, with diagnostic accuracies of 95.5% and 94.4%, respectively. Moreover, all interpretable PA results were considered positive (100% sensitivity).

CONCLUSION: Using EDTA anti-coagulated blood samples collected remotely, 1 and 2 days before testing, study results highlight the favorable diagnostic performance characteristics of the peanut BAT and provide further evidence that the test could be readily operationalized for clinical use by interested commercial reference laboratories.