Probing basophil function in microfluidic systems for allergic disease diagnosis

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PROJECT SUMMARY Basophils play important roles in allergic diseases: their activation is increasingly used for food allergy diagnosis, and their migration into tissues has been correlated with the onset of anaphylaxis. However, since basophils are rare, they are less studied and utilized for diagnostics than other leukocytes, especially in ex vivo microfluidic systems. The overall goal of this project is to fill this gap by developing enabling microfluidic technologies to better quantify basophil function, and by using food allergy as a model disease. Food allergy has reached epidemic proportions and has become a significant source of healthcare burden. Common in vitro allergy tests lack sufficient accuracy. Oral food challenge, the gold standard for food allergy assessment, is often not performed as it places the patient at risk of anaphylaxis. As such, food allergy is often identified only after an adverse reaction that could be life-threatening. In addition, there is no reliable correlation between the onset of anaphylaxis and a minimum offending dose of allergen. Metrics to predict anaphylaxis risk in a patient are essentially non-existent. Our long-term goal is to address these challenges by developing 1) allergy diagnostic tests that are accurate, safe, rapid, and accessible, and 2) metrics to better stratify patients at high risk of anaphylaxis. The overall objective of this pilot grant is to test the hypotheses that: 1) impedance changes in basophils upon activation, which exposes negatively-charged exteriorized granule proteoglycans, is an accurate and simple label-free indicator for basophil activation, and 2) basophil migration and secretion profile correlates with reaction severity. Our approach includes using whole blood samples from clinically-proven and well-characterized peanut allergic subjects and healthy controls, and leveraging our interdisciplinary team's expertise in innovative microfluidic technology and human immunology. We will: (Aim 1) design and validate a label-free impedance-based basophil activation test using whole blood in the presence of food allergen ex vivo, and (Aim 2) design and validate a coupled basophil migration and multiplexed secretion assay ex vivo to determine the correlation with patient history of anaphylaxis.