Loss of donor-specific Abs in mixed sensitized chimeras. Donor splenocytes were incubated with sera from naive mice (n = 10), sensitized mice (before BMT, n = 14), and chimeras (n = 14) prepared from sensitized mice 6 weeks to 6 months after BMT, followed by an anti-mouse immunoglobulin FITC secondary antibody, and then anti-mouse CD4 and CD8 PE. Levels of circulating alloantibodies were determined by FACSCalibur and by gating on the CD4⁺ and CD8⁺ T-cell fraction and were reported as MFI ± SD. One representative sample from each group is presented, and 3 separate experiments were performed.