Promotion of T-cell reconstitution after BMT. (A) BDF1 recipients were treated as described in the Figure 1 legend. On day 56, the spleens harvested from P815-injected GVHD recipients (HGF treated) were clearly enlarged relative to those from P815-injected GVHD recipients (control treated). (B) Total number of spleen cells. (C) MLR. Proliferative response of spleen cells to host antigens and alloantigens on day 56 after BMT. The mean counts per minute were as follows: unstimulated cultures for BMT controls, 1120 cpm; P815-injected GVHD (control treated), 1055 cpm; and P815-injected GVHD (HGF treated), 1098 cpm. (D) IL-2 production in response to host antigens and to alloantigens on day 56 after BMT. (E-F) BDF1 (Ly5.2) recipients were irradiated (9 Gy) and received TCD bone marrow cells (5 × 10⁶) from B6 (Ly5.1) donors and spleen cells (2.5 × 10⁷) from B6 (Ly5.2) donors plus P815 cells. Recipients were treated with HGF cDNA or a mock vector as described in the Figure 1 legend. BDF1 recipients that received TCD bone marrow cells (5 × 10⁶) from B6 (Ly5.1) donors were used as BMT controls. On day 56 after BMT, the number of Ly5.1⁺CD4⁺ T cells and Ly5.1⁺CD8⁺ T cells in the spleen were analyzed by flow cytometry (E). Spleen cells were treated with either anti-Ly5.1 mAb or anti-Ly5.2 mAb plus rabbit complement, and proliferative responses to host antigens were examined. The mean counts per minute were as follows: unstimulated cultures for P815-injected GVHD (control treated), 1551 cpm; and P815-injected GVHD (HGF treated), 1389 cpm (F). □ indicates BMT controls; ▪, P815-injected GVHD (control treated); and ▦, P815-injected GVHD (HGF treated). Data represent the mean ± SD from 3 mice. ^*P < .05 for P815-injected GVHD (control treated) versus P815-injected GVHD (HGF treated). Representative results from 2 similar experiments are shown.