Anti-LFA-1 induces CD8 T-cell dependent allograft tolerance and augments suppressor phenotype CD8 cells.

The induction of tolerance to transplanted organs is a major objective in transplantation immunology research. Lymphocyte function-associated antigen-1 (LFA-1) interactions have been identified as a key component of the T-cell activation process that may be interrupted to lead to allograft tolerance. In mice, αLFA-1 mAb is a potent monotherapy that leads to the induction of donor-specific transferable tolerance. By interrogating important adaptive and innate immunity pathways, we demonstrate that the induction of tolerance relies on CD8+ T-cells. We further demonstrate that αLFA-1 induced tolerance is associated with CD8+ CD28- T-cells with a suppressor phenotype, and that while CD8 cells are present, the effector T-cell response is abrogated. A recent publication has shown that CD8+ CD28- cells are not diminished by cyclosporine or rapamycin, therefore CD8+ CD28- cells represent a clinically relevant population. To our knowledge, this is the first time that a mechanism for αLFA-1 induced tolerance has been described.