INS and type 1 diabetes mellitus: The tolerogenic role of DN T cells in the prevention of T1D was first revealed using the P14/RIP-gp transgenic mouse model (Ohashi et al., 1991), where the MHC class I-restricted P14 TCR transgene recognizes the lymphocytic choriomeningitis virus (LCMV) protein, gp33–41 (gp33), which is expressed under the rat insulin promoter (RIP) forcing its expression in the pancreatic tissue.