Idd9.1 Locus Controls the Suppressive Activity of FoxP3CD4CD25 Regulatory T-Cells

OBJECTIVE—The 45-cM insulin-dependent diabetes 9 (Idd9) region on mouse chromosome 4 harbors several different type 1 diabetes–associated loci. Nonobese diabetic (NOD) mice con-genic for the Idd9 region of C57BL/10 (B10) mice, carrying antidiabetogenic alleles in three different Idd9 subregions (Idd9.1, Idd9.2, and Idd9.3), are strongly resistant to type 1 diabetes. However, the mechanisms remain unclear. This study aimed to define mechanisms underlying the type 1 diabetes resistance afforded by B10 Idd9.1, Idd9.2, and/or Idd9.3. RESEARCH DESIGN AND METHODS—We used a reduction-ist approach that involves comparing the fate of a type 1 diabetes–relevant autoreactive CD8 T-cell population, specific for residues 206–214 of islet-specific glucose 6 phosphatase catalytic subunit–related protein (IGRP206–214), in noncongeni