Figure 5. Melanoma-specific memory T cells are maintained in vitiligo-affected mice despite hyporesponsiveness to homeostatic cytokines.
(A–C) Mice were treated as in Figure 1A. (A) 260 days after surgery, IFN-γ ELISPOT was performed on CD8+ T cells from pooled lymph nodes (5–8 mice/group), with peptide-pulsed EL4 cells as targets. Vitiligo was classified as described in Figure 1. Data represent average ± SD of 4 replicate wells. (B–D) Mice received 104 naive Thy1.1+ pmel cells 1 day prior to treatment as in Figure 1A. Symbols represent individual mice, and horizontal lines represent averages. (B) At various times following surgery, the proportion of pmel (Thy1.1+) cells among total CD8+ T cells in lymph nodes was assessed by flow cytometry. Data from unaffected and vitiligo-affected mice were statistically different (P < 0.05 by t test) at all time points except day 90. (C) 215 days following surgery, CD8+Thy1.1+CD44hi pmel cells were assessed for expression of phenotypic markers. Histograms depict data from representative lymph node samples. (D) Thirty days after surgery, CD8+ T cells were isolated from spleens of vitiligo-affected mice and cultured with IL-15 or IL-7, and the proportion of Thy1.1+CD44hi pmel cells undergoing at least 1 round of division (% Proliferated) was assessed by CFSE dilution. Host memory phenotype T cells (CD8+CD44hiThy1.1–) were analyzed as a positive control. Symbols represent single wells; the experiment was performed 3 times, with similar results. Statistically significant differences were assessed by t test, with *P < 0.05, **P < 0.01, and ***P < 0.001.