Eosinophil Interaction With Matrix-Producing Lung Cells: An In Vitro Model System Employing AML14.3D10 Eosinophil-Like Cells To Interact With AH1F Fibroblasts And A549 Epithelial Cells

Abstract

The extracellular matrix protein fibronectin is found in the airway space after bronchial provocation and can extend the life of eosinophils in vitro. Herein we describe a system to study the effect of co-culture of eosinophil-like cells with cell lines derived from tissues. We compared integrin engagement on human peripheral blood eosinophils to several eosinophil-like cell lines, including EoL-3, AML 14.3D10, and HL-60 clone 15 cells. Effects of co-incubation of AML 14.3D10 cells with adherent cell AH1F fibroblasts or A549 epithelial cells were examined for adhesion, metabolic activity (reduction of cytochrome C), and fibronectin production. AML 14.3D10 cells had the ability to bind to the adherent cells, however the interaction was not reduced by blocking integrins on the eosinophil-like cells. The amount of fibronectin found in association with the extracellular matrix of AH1F fibroblasts or A549 epithelial cells as measured by ELISA was not altered when AML 14.3D10 cells were included as a co-culture. The co-cultures were separated into three fractions to measure fibronectin that was secreted into the medium or fibronectin associated with non-adherent cells, and also fibronectin associated with adherent cell extracellular matrices. Fibronectin was detected all three fractions, indicating that secreted fibronectin was not limited to incorporation within the extracellular matrix of adherent cells. Thus both fibroblasts and epithelial cells are capable of producing soluble cellular fibronectin and either may be the source of soluble cellular fibronectin found in the lungs of asthmatics after bronchoprovocation.