A new model for studying eosinophil migration across cultured intestinal epithelial monolayers

Eosinophils play an important role in some gastrointestinal inflammatory conditions. Stimulated eosinophils migrate across the vascular endothelial wall and into the intestinal epithelium where by-products such as proteases may contribute to intestinal epithelial damage. Little is known about the epithelial migration of the eosinophils in the gut. The lack of data is attributable in part to the scarcity of human eosinophils for studies. HL-60-differentiated eosinophils present a means to perform studies on eosinophil function and chemotaxis. HL-60 clone 15 can be induced to differentiate into cells closely resembling human eosinophils. The authors describe a novel model for studying eosinophil migration across the intestinal epithelium.

Fluorescent-labeled HL-60 eosinophils were incubated for 150 minutes on the basolateral surface of confluent and inverted T-84 monolayers separated by fluoroblock insert membranes. Chemotactic gradients of n-formyl methionyl leucyl phenylalanine (fMLP), eotaxin, and platelet aggregating factor (PAF) were used in variable concentrations. Changes in transepithelial electrical resistance (TEER) were compared with baseline values.

Differentiated HL-60 eosinophils undergo migration in response to fMLP, PAF, and eotaxin. Migration is associated with a drop in TEER.

In this model, HL-60-differentiated eosinophils migrate in response to stimulants chemotactic for human eosinophils. The transepithelial migration of eosinophils is associated with epithelial barrier dysfunction, which may contribute to the development of disease.