Figure 3. Expression of CD44, SLAMF6, and CXCR6 defines three subsets of islet-infiltrating CD8 T cells.

(A) Representative flow cytometry plots depicting the gating strategy of three CD8 T cell subsets and the corresponding expression of TCF1 (B), LAG3 (C), PD-1(D), TIM3 (E), and granzyme B (F) in pancreatic islets of 10–13-week-old female NOD mice. The black line with grey shaded area shown in the histogram of panel (F) represents the isotype control staining of CD44^high CD8 T cells. For granzyme B expression, the cells were stimulated ex vivo with PMA and ionomycin. Cells are gated on single viable CD45.1⁺CD3⁺CD4⁻CD8⁺ cells. Summarized geometric mean fluorescent intensity (MFI) results are from 2–3 independent experiments. Each symbol represents islet cells pooled from two mice (n=5 pools/group). The horizontal line indicates the mean. *p<0.05, **p<0.01 by Wilcoxon rank-sum test. (G) CD8 T cell subsets among NRP-V7 MHC-I tetramer positive and negative cells harvested from islets of 7–12-week-old female NOD mice. Cells are initially gated on single viable CD45.1⁺CD3⁺CD4⁻CD8⁺ cells. Representative flow cytometry plots depicting the CD8 T cell subset gating strategy are shown (Left). The relative proportion of TCF1⁺CXCR6⁻ and TCF1⁻CXCR6⁺ CD8 T cells among CD44^high MHC-I tetramer positive and negative cells is summarized (Right). Results are combined from 3 independent experiments. Each symbol represents a mouse, and the horizontal line is the mean. **p<0.01, ***p<0.001, ****p<0.0001 by Wilcoxon rank-sum test.