Homeostatic peripheral expansion of antigen-specific cells requires antigen presentation by dendritic cells. T cell-depleted hosts were generated by thymectomizing C57BL/6 female mice at 5 weeks of age and then treating with anti-CD4 and anti-CD8 as described in “Materials and methods.” (A) On day -14, T cell-depleted animals received 25 × 106 HY naive female lymph node cells intravenously as a source for homeostatic peripheral expansion and 1 × 106 male splenocytes intraperitoneally (solid line with triangles, n = 10) or 1 × 105 male dendritic cells intraperitoneally (solid line with squares, n = 12). T cell-replete normal C57BL/6 females received no cells (dashed line with circles, n = 8), 1 × 106 male splenocytes intraperitoneally (dotted line with diamonds, n = 9), or 1 × 105 male DCs intraperitoneally (dotted line with triangles, n = 8). Male tail skin grafts were applied on day 0 and monitored visually for rejection. There was a statistically significant difference in time to graft rejection between T cell-depleted mice immunized with male spleen versus male DCs (P = .0008). (B) T cell-replete females (bottom panels) and T cell-depleted females receiving 25 × 106 female LN cells intravenously as a source for HPE (top panels) received intraperitoneal injections of 1 × 105 male DCs (left panels) or 1 × 106 male splenocytes (right panels). Twenty-eight days later, splenocytes binding to an MHC class I tetramer containing the HY immunodominant peptide derived from Uty were enumerated. Shown are contour plots of gated CD8+ T cells from representative animals from each group. Consistent results were seen in 3 experiments. Percentage of CD8+ cells that bind tetramer are shown.
