Generation of a monoclonal antibody that blocks epithelial binding of unopsonized particles.

Alveolar macrophages (AMs) and epithelial cells (ECs) are the first cells in the lung to encounter inhaled environmental particles. The initial interaction between AMs and particles is mediated by specific scavenger receptors, but the nature of the structure(s) on ECs that also bind particles has not been well-described. To characterize the nature of the EC particle receptor, we screened a panel of mouse anti-human EC hybridomas for functional blockade of EC particle binding. This strategy identified a monoclonal antibody (MAb) (EPR1) that blocks binding of titanium dioxide (TiO2) particles to the EC line which served as the immunogen (A549), as well as to other EC lines (Beas 2-B, HTB54, HeLa, and MDA-MB-435S). EPR1 demonstrated specific labeling of ECs using immunohistology techniques and its expression could be quantitated by flow cytometry of permeabilized ECs in suspension. MAbs such as EPR1 may prove useful in further analysis of receptors for inhaled particles on lung epithelial cells.