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An Integrated Micro-Basophil Activation Test for Rapid Food Allergy Diagnostics


Food allergy has reached epidemic proportions and has become a significant source of healthcareburden. Accurate in vitro methods that are efficient and easy to use to identify offending foodallergens are lacking. Oral food challenge, the gold standard for food allergy assessment, is oftennot performed as it places the patient at risk of anaphylaxis. As such, food allergy is often identifiedonly after an adverse reaction that could be life-threatening. We have shown that BasophilActivation Test (BAT), which measures the activation of basophils in whole blood after stimulationwith specific food allergens ex vivo, is highly predictive of allergic reactions. However, currentmethod relies on the detection of multiple markers to identify basophils and their activation status.This requires multi-color flow cytometers which are not widely accessible, and has in turn limitedthe broader adoption of BAT in clinical practices for food allergy assessment. There is a criticalneed for an alternative marker that is accurate, robust and simple, together with a rapid way toperform and analyze test results, ideally at the point of care.Our long-term goal is to develop a food allergy test that is accurate, safe, rapid, and accessiblethat can complement or even replace oral food challenge as the gold standard assessment offood allergy, so that: 1) food allergy can be easily identified prior to the occurrence of an adversereaction either at the doctor's office or at home, and 2) the efficacy of immunotherapy for foodallergy can be tracked more effectively. The overall objective of this pilot grant is to test thehypotheses that: 1) we can use a change in the surface charge of basophils to measure theiractivation status, and that the binding of avidin, a positively-charged molecule, is sufficientlyaccurate to replace current markers for indicating basophil activation, and 2) the test for basophilactivation can be performed on a standalone biochip without compromising the accuracy of thetest conventionally performed using flow cytometers. Our approach includes using whole bloodsamples from already clinically-proven and well-characterized peanut allergic subjects andhealthy controls, and using our team's microfluidics and instrumentation capability forminiaturizing BAT onto a biochip. To test these hypotheses, we will: (Aim 1) determine whetherthe presence of food allergy can be determined by the avidin binding test using 100 uL of wholeblood to measure basophil activation ex vivo using a conventional flow cytometer, and (Aim 2)design and validate a rapid micro-BAT (?uBAT?) on a biochip using 100 uL of whole blood tomeasure basophil activation in the presence of food allergen ex vivo.

Tang, Sindy Kam-yan
Stanford University
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