CYTOKINE PRODUCTION BY EPITHELIAL-CELLS

The epithelium has long been regarded as a passive barrier intended to protect the underlying tissues. Many regulatory signals, including cy tokines, that control epithelial cell proliferation and differentiatio n and cell function during inflammation were thought to be nonepitheli al-derived. Now there is a growing appreciation that epithelial cells provide some of the impetus for their own growth and differentiation, and may also regulate the function of other cells through the elaborat ion of certain cytokines. Moreover, because epithelial cells serve as the interface between the organism and environment, they are in a posi tion to signal changes in the environment. It is now clear that epithe lial cells respond to injury or infection with cytokine secretion. Var ious approaches to detecting cytokines in normal and diseased tissue h ave been undertaken during the past few years to establish cytokine sy nthesis by different epithelia. This review will examine these recent investigations in various general contexts of epithelial cell function .