Figure 2. Liposomal clodronate pretreatment enhances mixed hematopoietic chimerism and donor-specific skin allograft tolerance.

Mice receiving BM transplantation were subjected to both BALB/c and CBA/Ca skin transplantation both 90 days (primary allografts) and 180 days (secondary allografts) later, as indicated in Fig. 1. (A) Clodronate-enhanced mixed hematopoietic chimerism. The percentage of cells expressing BALB/c MHC-class I (H-2K^d) in peripheral blood, expressed as mean ± SEM, was checked at the time-points after BM transplantation coded at the upper right. (B) Donor-specific tolerance. The same representative recipient mouse with all four skin allografts in place (two primary and two secondary to the left & right of the dotted line, respectively) is shown at the time points indicated to the left of each image. Arrows indicate the position of each skin transplant. (C,D) Quantitation of donor-specific tolerance for the primary (C) and secondary (D) skin allografts. The symbol code defining the number of transplanted BM cells and the dose of liposomal clodronate in each skin graft type is shown in the boxes above panels C and D; the number of mice in each group is given in the parentheses next to each symbol.