Eosinophilic Esophagitis (EoE) is a chronic, allergic inflammatory disease that presents with elevated numbers of eosinophils in the esophagus, and is caused by contact with food allergens. However, little is known about the mechanism by which food allergens diffuse into the esophagus to contact and activate immune cells, leading to the recruitment of eosinophils. A better understanding of this mechanism of diffusion would allow for the development of more targeted treatments for EoE. The objective of this project was to establish a working assay to determine the diffusion rates of various fluorescent dyes through regenerated cellulose membranes that can later be applied to fluorescently labeled food proteins and human esophageal tissue. In testing our assay, we found the observed diffusion rates of different fluorescent molecules across synthetic membranes fit our mathematical model for rates of diffusion. In preliminary studies, we demonstrated that our assay and mathematical model for diffusion rates could be applied not only to synthetic membranes, but also to human esophageal tissue. The results of this project have provided the lab with a model that can be applied to different membranes and fluorescently labeled molecules to measure diffusion rates with a relatively high level of accuracy. Future steps will be to fluorescently label food proteins commonly implicated in EoE, and measure the diffusion rates through normal human esophageal tissue, as well as the diffusion rates after administration of various potential EoE treatments such as steroids and antihistamines.