Figure 1.

Reduced % CD8 T cells in the Idd9 congenic islet infiltrate. Islet infiltrating cells were isolated from the islets of Idd9 congenic and NOD mice for analysis by flow cytometry. Dot plots showing representative CD4 and CD8 staining, gated on the CD45+ population (A), and the range of values for %CD8+ and %CD4+ cells (B) are also shown. Results representative of > 6 independent experiments (mice aged 12–14 weeks). The presence of CD8+ cells in the islets of Idd9 congenic and NOD mice was also determined by confocal microscopy of frozen pancreatic sections (C). Sections (10 μm) from 12–14 week old mice were stained with antibodies to CD8 (green) and insulin (red), and Topro-3 (blue) was used to visualize nuclei. A total of 27 infiltrated islets from 4 Idd9 congenic mice, and 36 infiltrated islets from 4 NOD mice were examined. The islets were imaged from three different levels through each pancreas, each level separated by at least 300 μm. Lower panels show fluoroscein staining only to aid comparison of CD8 infiltration between Idd9 congenic and NOD islets. Islets from the two strains exhibiting similar areas of infiltration were compared (i-iv show minor infiltration, and v-viii an extensive infiltrate). Original magnification 40 ×. In (D), flow cytometry staining of the activation marker CD44 on CD4 and CD8 T cells isolated from the islet infiltrate of 12–14 week old mice is shown. Bars and adjacent numbers in plot indicate average value. n = 6, representative of 2 independent experiments. The % CD4 and CD8 T cells in peripheral blood and secondary lymphoid organs of 6 week old Idd9 congenic mice was also determined by flow cytometry (E). Average values +/- SEM are shown. n = 4, representative of 2 independent experiments.