Figure 5. Tregs attract CD8⁺ T cells in vivo via a CCL3/4-CCR5 dependent mechanism.

Tregs were sorted from WT, OTII, or Ccl3^–/– mice, and CD8⁺ T cells were sorted from WT or Ccr5^–/– mice. (A and B) 2 × 10⁶ sorted OTII Tregs or Tconv cells were injected into the rear right and left feet, and a mixture of OVA 323–339 and CpG in alum was injected into the right foot only. After 18 hours, CPD-labeled WT or Ccr5^–/– CD8⁺ T cells were injected i.v. After 40 hours, the ratio of WT or Ccr5^–/– CD8⁺ T cells in the right and left draining inguinal lymph nodes was determined. (A) Schematic of the experimental setup. (B) Summary of the experiments, depicting the ratio of labeled WT or Ccr5^–/– CD8⁺ T cells in the right versus left draining inguinal lymph nodes (n = 4–6 for each group, from 3 experiments), paired t test. **P < 0.01. (C and D) The right foot was injected with 1 × 10⁶ WT or Ccl3^–/– Tregs, which had been stimulated in vitro, and 2 hours later, WT or Ccr5^–/– CD8⁺ T cells were injected i.v. (C) Schematic of the experimental setup. (D) Summary of the experiments. Each dot represents the right/left ratio from an individual mouse (n = 2–3 for each group, from 2 experiments); paired t test. *P < 0.05; **P < 0.01.