Specific Acceptance of Cardiac Allograft After Treatment with Antibodies to ICAM-1 and LFA-1

An indefinite survival of cardiac allografts between fully incompatible mice strains was observed when monoclonal antibodies (MAbs) to intercellular adhesion molecule-1 (ICAM-1) and leukocyte function-associated antigen-1 (LFA-1) were simultaneously administered after the transplantation for 6 days. Mice with long-term surviving cardiac allografts accepted skin grafts from the donor-strain but rejected skin grafts from a third-party strain. Because MAbs to ICAM-1 or LFA-1 alone were insufficient for prolonged tolerance, the two MAbs probably acted synergistically to induce specific unresponsiveness. Thus, ICAM-1----LFA-1 adhesion participates in the induction of allograft rejection and MAbs may be useful as therapeutic agents.