Since the induction of leukocyte trafficking determinants by the CP is dependent on epithelial IFN-γ signalling17, and IFN-γ levels at the CP were found to be reduced in brain aging25, 26 and under neurodegenerative conditions20, we next-tested whether the observed effects in AD-Tg mice could reflect loss of IFN-γ availability at the CP. Here, CP is linked to Alzheimer disease.