Epithelial cells and expression of the phagocytic marker CD68: scavenging of apoptotic bodies following Rho activation.

Macropinocytosis is a ruffling-driven process which drives the ingestion of large particles by both macrophages and epithelial cells. In this context, we have previously described a Rho-activating bacterial toxin from E. coli, the cytotoxic necrotizing factor 1 (CNF1), which allows epithelial cells to macropinocytose not only latex beads and bacteria, but also apoptotic cells in a fashion similar to that of professional phagocytes. We herein report that (i) epithelial cells express the typical phagocytic marker CD68, (ii) Rho activation by CNF1 varies the intracellular localization of CD68, which appears to be co-distributed, as in macrophages, with the homologous lysosomal protein Lamp-1. Together with the capability of digesting apoptotic cells following their internalization, our findings indicate that Rho-activated epithelial cells behave in most respects as professional phagocytes.