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The bronchial epithelium: a potential allogeneic target for chronic rejection after lung transplantation.

BACKGROUND
The presumptive target of the immune response in chronic pulmonary allograft rejection is the bronchial epithelium.


METHODS
To further characterize human bronchial epithelial cells with regard to their ability to function as immunologic targets, cell surface antigen expression, lymphocyte proliferation, and messenger ribonucleic acid coding for a panel of mesenchymal growth factors were determined in the BET-1A human bronchial epithelial cell line.


RESULTS
Interferon-gamma up-regulated cell surface intercellular adhesion molecule 1 and major histocompatibility class I and class II antigen expression by flow cytometry. Of note, tumor necrosis factor-alpha had no effect on these cell surface antigens. With the use of purified T cells from buffy coats obtained from normal volunteers, both resting and, to a greater extent, interferon-gamma-pretreated BET-1A cells stimulated lymphocyte proliferation. Finally, resting BET-1A cells expressed messenger ribonucleic acid coding for a number of mesenchymal growth factors known to stimulate smooth muscle cell migration and proliferation, the hallmark of the obliterative bronchial lesion.


CONCLUSIONS
Bronchial epithelium is capable of eliciting an allogeneic immune response and expresses a number of growth factors that could potentially play a role in the development of obliterative bronchiolitis.