The effect of spleen cell preexposure on B6.SJL engraftment into 0-cGy or 100-cGy anti-CD40 ligand mAb–treated BALB/c hosts.

Male BALB/c hosts either unirradiated (groups I-IV) or exposed to 100 cGy (groups V-VIII) were infused with 40 million male B6.SJL cells on day 0 and injected intraperitoneally with 1.6 mg anti-CD40 ligand mAb on days −10, −7, −3, 0, and +3 (groups II-IV and VI-VIII) or given no anti-CD40 ligand antibody (groups I and V). Spleen cell (SC) sensitization was omitted in groups II and VI or given on day −7 (groups III and VII) or day −10 (groups IV and VIII). Data are expressed as percentage (%) CD45.1 cells in peripheral blood out to 31 weeks after transplantation. There were 5 transplanted mice per group initially. Between weeks 12 and 13 all mice received an infusion of 40 million B6.SJL (sex-matched) marrow cells. Asterisks indicate groups that had received a second marrow transplant; W, weeks; L, ligand; D, day.