1. Ag governs CTL behavior at islets but is not required for their accumulation in large numbers.
Ag governs CTL behavior at islets but is not required for their accumulation in large numbers. (A) Islet (dashed line) in the pancreas of a diabetic RIP-GP mouse where islet-specific P14 CTLs (red) and non–islet-specific OT-I CTLs (green) have gathered. (B) An islet (dashed line) in the pancreas of a wt C57Bl/6 mouse immunized in the same way as in (A) displaying a few CTLs in the pancreatic parenchyma. (C and D) The levels of T cell proliferation were similar between the two strains of mice, as judged by T cell content in spleens. (E to G) The densities of accumulated CTLs of both specificities (P14 and OT-I) were higher in the islets than in the surrounding pancreatic parenchyma, as quantified in (E) (n = 5 mice) and visualized in (F) and (G), where the yellow line across a part of the pancreas in (F) is represented in the histograms over fluorescent signals in (G). (H) Islets in mouse pancreata were imaged in anesthetized mice using a vacuum imaging window where the pancreas was immobilized, enabling long-term imaging. (I and J) A still frame (z-projection) (I) from an intravital recording of an inflamed islet in a RIP-GP mouse (red P14 CD8+ T cells and green OT-I CD8+ T cells) and the resulting T cell tracks (J). (B) and (C) correspond to movie S3. (K and L) OT-I CTLs consistently displayed higher migration speeds than the islet-specific P14 CTLs (K) and were kept, on average, further away from the islet center (L). Data in (J) to (L) are from one of six representative experiments. Data are means ± SEM. *P < 0.05, two-tailed unpaired Mann-Whitney U tests. Scale bars, 20 μm (A to D), 30 μm (F), and 50 μm (I and J).
Gustaf Christoffersson et al. Sci. Immunol. 2018;3:eaam6533
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