Long Island University 1 article published in JoVE Immunology and Infection In Vivo Augmentation of Gut-Homing Regulatory T Cell Induction Hongzheng Bi1,2, Samiksha Wasnik1, David J. Baylink1, Chenfan Liu1,3,4, Xiaolei Tang1,3 1Division of Regenerative Medicine, Department of Medicine, Loma Linda University, 2Zhengzhou University, 3Department of Veterinary Biomedical Sciences, College of Veterinary Medicine, Long Island University, 4Jinan Infectious Disease Hospital, Shandong University Here we present a protocol for in vivo augmentation of gut-homing regulatory T cell induction. In this protocol, dendritic cells are engineered to locally produce high concentrations of the active vitamin D (1,25-dihydroxyvitamin D or 1,25[OH]2D) and the active vitamin A (retinoic acid or RA) de novo.