Mast Cell Activation Test in Allergic Disease

Overview

Activation of mast cells in the immune system is known to cause allergic reactions sometimes with severe systemic symptoms. The investigators have recently developed a blood-based mast cell activation diagnostic test in which levels of functional activation in-vitro in primary cultured mast cells generated from the peripheral blood of single individuals can be assessed. It is the hypothesis that the test can be used to predict the potential state of in-vivo mast cell activation in any individual based on the functional activation profiles exhibited by their cultured mast cells. The investigators now wish to translate their in-vitro findings in a pilot study to disease groups where mast cell activation is expected to be high. These include highly allergic individuals; those with chronic idiopathic urticaria; those with mastocytosis; and those with the mast cell activation syndrome. Furthermore, they will use the functional genomics approach to identify gene expression biomarkers that are correlated with such diseases. The results will be compared with data that have been collected from a cohort of healthy control blood donors.

The objective of this study is to assess whether patients with severe allergic diseases exhibit high levels of mast cell activation as determined by the mast cell activation diagnostic test the investigators have developed. They anticipate that patients with history of severe allergic reactions will show up as high responders in the blood-based mast cell activation diagnostic test. Moreover, using microarray analysis as the approach for gene expression studies, they anticipate further that genomics biomarkers that are correlated with the high functional activation of the in-vitro mast cells derived from these patients can be readily identified. About 100 ml of peripheral venous blood from individual patients will be drawn into heparinized syringes and collected in a blood-collecting bag/tube containing silica. The bag/tube will be promptly processed for the generation of primary human mast cell cultures using the protocol that has previously been developed \[Inflammation Research 66: 25 (2017). After culturing for 9 weeks, the resulting human mast cells will be analyzed for both their functional activity in terms of histamine release in response to the activation of high-affinity Immunoglobulin E (IgE) receptors in these cells and their gene expression profiles using microarray analysis. The in-vitro functional and genomics data will be correlated with specific diagnoses and measurements of blood prostaglandin D2 (PGD2), PGD2 metabolites, tryptase and histamine levels in blood. For mediator assays, plasma from each subject will be collected after the cluster of differentiation 34 positive (CD34+) isolation step and the samples will be aliquoted and frozen at -80 degrees centigrade for subsequent analysis.