Intrathymically injected HSPCs contribute to T-cell reconstitution after BMT. (A) Lethally irradiated C57BL/6 recipients were transplanted with C57BL/6.CD45.1+ Lin− BM cells and received 3000 C57BL/6.Thy1.1+ luciferase-expressing LSK cells via ITI 2 hours after irradiation (LSK group). Control mice received Lin− BM only and phosphate-buffered saline (PBS) via ITI 2 hours after irradiation. Thymuses were harvested on day 60 after BMT and analyzed for BM donor and LSK donor origin and CD4 and CD8 DN, DP, SP populations. (i) Mean and SEM of total thymocyte counts are presented (n = 5). (ii-iv) Representative plots of 1 of 5 LSK group samples. Combined data from 2 independent experiments are presented. (B) Animals were treated as described in panel A. Splenocytes were harvested on day 60 after BMT and analyzed for splenic T-cell populations of donor and host origin. Mean and SEM are presented (n = 5). Combined data from 2 independent experiments are presented. (C) Animals were treated as described in panel A. Thymuses were harvested 6 months after BMT and analyzed for BM donor and LSK donor origin and CD4 and CD8 DP, SP, and DN populations. (i) Mean and SEM of total thymocyte counts are presented (n = 4-5). (ii-iv) Representative plots of 1 of 4 LSK group samples. (D) Animals were treated as described in panel A. Splenocytes were harvested 6 months after BMT and analyzed for splenic T-cell populations of donor and host origin. Mean and SEM are presented (n = 4-5). (E) Lethally irradiated BALB/c recipients were transplanted with C57BL/6 TCD BM cells and received 5,000 C57BL/6.CD45.1+ LSK cells via ITI 2 hours after irradiation (LSK group). Control mice received TCD BM only and PBS via ITI 2 hours after irradiation. Thymuses were harvested on day 60 after BMT and analyzed for BM donor and LSK donor origin and CD4 and CD8 DP, SP, and DN populations; 1 of 3 independent experiments is presented. (i) Mean and SEM of total thymocyte counts are presented (n = 4). (ii-iv) Representative plots of 1 of 4 LSK group samples. (F) Animals were treated as described in panel E. Splenocytes were harvested on day 60 after BMT and analyzed for splenic T-cell populations of donor and host origin. Mean and SEM are presented (n = 4). (G) Animals were treated as described in panel E. Thymuses were harvested 6 months after BMT and analyzed for BM donor and LSK donor origin and CD4 and CD8 DP, SP, and DN populations. (i) Mean and SEM of total thymocyte counts are presented (n = 4). (ii-iv) representative plots of 1 of 4 LSK group samples. (H) Animals were treated as described in panel E. Splenocytes were harvested 6 months after BMT and analyzed for splenic T-cell populations of donor and host origin. Mean and SEM are presented (n = 4).