The Effect of Macrophage Migration Inhibitory Factor on Intestinal Permeability: FITC-Dextran Serum Measurement and Transmission Electron Microscopy.

Macrophage migration inhibitory factor (MIF) is a molecule with multiple functions: from enforcing the immune system to fight bacterial infection to the regulation of insulin activity. Also, MIF is expressed by enterocytes that line the intestinal border toward the lumen, and in M cells, where it regulates phagocytosis of antigens from the lumen of the gut and their transport to Peyer's patches. Since there were no data on the role of MIF in the maintenance of the intestinal barrier, we used MIF-deficient mice bred on C57BL/6 background as a model for the investigation of intestinal permeability. The obtained results indicate that the absence of MIF increases intestinal permeability. Here we describe two methods for measuring intestinal permeability in mice: detection of orally delivered FITC-dextran in the serum and transmission electron microscopy used for visualization and measurement of cell-to-cell connections width.