Engraftment of B6.SJL marrow into 100- cGy irradiated BALB/c hosts pre-exposed to B6.SJL spleen cells and treated with anti-CD40 ligand (L) monoclonal antibody (mAb).

BALB/c hosts were infused with 10 million B6.SJL spleen cells (SC) on day −10. Immediately before spleen cell infusion and on days −7, −3, 0, and +3 BALB/c hosts were injected with varying amounts of anti-CD40 ligand (mAb) intraperitoneally. These mice were subjected to 100-cGy WBI and infused with 40 million B6.SJL marrow cells on day 0. Donor chimerism was determined by staining peripheral blood cells with CD45.1 antibody and analyzing individual mice by FACS. Data are expressed as percent engraftment out to 47 weeks after transplantation. There were initially 5 mice per group. Group I had 4 mice per group after week 9, and group VI had 4 mice per group after week 16. At 47 weeks, smaller numbers of mice were in each group due to the use of mice for other experimental points. Groups V and VI were statistically different from groups I, II, and III at all time points, P < .02 and P < .01, respectively. W indicates weeks.