Fig. 3.

“Humanized” mice for type I diabetes research carry human major histocompatibility complex (MHC) alleles. a Schematic of the regions encoding MHC genes: HLA in humans (top) and H2 in mice (bottom). Class I MHC genes are depicted in purple, class II genes in green; human genes are stippled. b In “humanized” NOD mice, H2.K and H2.D have been genetically ablated (black “x” plus lightning bolt). NOD mice naturally harbor mutations (red “x”) in H2.E and H2.L, and thus H2.A (class II) is the only functional MHC gene remaining in the H2 locus. Human HLA alleles (class I; HLA.-A2.1 or HLA-.B39) are replaced as a transgene to restore T1D susceptibility to otherwise T1D-resistant, class I-deficient mice