Fig. 1

Memory CD8⁺ T cells densely cluster at sites of early immune activation. a Schematic of OT-I T cell adoptive transfer and subsequent memory OT-I T cell generation via VSV-OVA infection. b Schematic of (bystander-activating) WT LM immunization and subsequent tissue sampling. c–h Representative 8 µm, whole-spleen sections showing OT-I (red), MMM (cyan), and LM Ag (green). c Whole-spleen section and magnified selection d from LM-unimmunized OT-I memory mouse. e Whole-spleen section and magnified selection f from OT-I memory mouse 24 h post WT LM (bystander-activating) immunization. g Whole-spleen section and magnified selection h from animal 7 days post OT-I transfer and LM-OVA immunization, showing OT-I effector (Ag-specific) response. i Raw IF images showing OT-I (red), MMM (cyan), LM Ag (green), and DAPI (gray), and cell identity outputs used for cell enumeration (OT-I, red; MMM, cyan; co-staining, white; nuclei, gray) from HALO digital pathology software. j Splenic OT-I T cell densities from WT LM Ag-positive and -negative WP as enumerated from HALO-analyzed IF images. In c–h image contrast of single-channel images was increased using Adobe Photoshop equally across all samples prior to layer compilation. Pixel size for LM Ag channels was doubled to increase visibility using Adobe Photoshop. c, d Is representative of n = 6. e, f is representative of n = 10. g, h is representative of n = 3. In j each individual symbol (mock immunization) or connected symbol pair (24 h post WT LM immunization) represents one animal from 3 experiments (n = 6 mock-immunized, n = 10 WT LM-immunized). Indicated are statistical significances by Wilcoxon matched-pairs signed rank test. See also Supplementary Fig. 2. Source data are provided as a Source Data file