Fig. 3.

CD137 costimulation instigates luminal infiltration of activated effector CD8 T cells. A: hyperlipidemic CD45.2 wild-type (WT) mice received adoptive transfer of CD45.1 Ova-specific splenocytes 2 wk after PCAL and were immunized with SIINFEKL + rat IgG control or agonist anti-CD137 mAb. B: confocal microscopy of ligated carotid vessels 4 days postimmunization (dpi) with either control IgG treatment or CD137 costimulation stained for endothelial cells (CD31; green), Ova-specific transferred CD8 T cells (CD45.1; red), and DAPI (blue). White squares demarcate magnified images below, and arrows indicate infiltrating effector CD8 T cells. (top scale bar, 50 µm; bottom scale bar, 20µm). Intima (I), medial (M), and adventitial (A) layers of the developing plaque are indicated by dashed lines. C: total count of transferred CD8 T cells per carotid vessel cross-section (left) and localization of cells either within intima (top right) or at the lumen surface (bottom right) in partial carotid artery ligation (PCAL)-carotid cross-sections of mice that received transfer of CD45.1 WT Ova-specific CD8 T cells and immunization with SIINFEKL + rat IgG control or agonist anti-CD137 mAb. ^nsP = 0.09, **P < 0.006 by 2-group t-test; n = 5 mice/group. Data shown are from 1 experiment representative of 2 experimental replicates. HFD, high-fat diet. Data points from individual mice are as follows: ◆, mice with CD137 co-stimulation; ◇, IgG-treated controls.