Fig. 4. CVB-reactive CD8⁺ T cells are also found in spleen and PLNs and display a PD-1⁺ phenotype.

(A and B) Detection of CVB epitope–reactive CD8⁺ T cells in splenocytes from nPOD organ donors (HLA-A2⁺, left; and HLA-A3⁺, right; see details in table S3). Each symbol represents a donor, and bars indicate median values. (A) depicts the frequency of MMr⁺CD8⁺ T cells out of total CD8⁺ T cells, with the horizontal line indicating the 10⁻⁵ frequency cutoff. A median of 73,320 CD8⁺ T cells were counted (range 9,611 to 307,697). Only epitopes testing positive are depicted (complete peptide panels listed in fig. S5A). (B) displays the percent effector/memory fraction within each MMr⁺CD8⁺ population for those donors/epitopes with ≥5 MMr⁺ cells counted. (C and D) CVB epitope–reactive CD8⁺ T cells in lymphoid tissues from nPOD cases. CVB MMr⁺CD8⁺ T cell frequencies (C) and percent PD-1⁺CD25⁻ MMr⁺ cells (D; for donors/epitopes with cell counts of ≥5) across available tissues are depicted. (E) Comparison of PD-1⁺CD25⁻ fractions between CVB and influenza virus MMr⁺CD8⁺ T cells detected in the same PLN; *P = 0.014 by Wilcoxon signed rank test. (F) Expanded TCR CDR3β clonotypes in individual CVB1/CVB3_{1356–1364/1359–1367}-reactive CD8⁺ T cells from the same nPOD cases/tissues. Expanded clonotypes were defined as those found in ≥3 MMr⁺ cells in the same tissue from the same donor and are clustered according to frequency (one columns per tissue/case) and sequence similarity (one row per CDR3β clonotype). Further details are provided in figs. S5 and S6. ND, nondiabetic.