ROLE OF THE ENDOTHELIAL ADHESION MOLECULE VCAM IN MURINE CARDIAC ALLOGRAFT-REJECTION

Murine heterotopic cardiac isografts (C57Bl/6 --> C57Bl/6) undergo transient, non-destructive inflammation that is characterized by the acquisition of microvascular endothelial reactivity with the antibody MECA 32. Cardiac allografts (C57Bl/6 --> DBA/2) undergo destructive inflammation that is characterized by the acquisition of reactivity with the antibody M/K-2, in addition to MECA 32. M/K-2 recognizes the murine endothelial adhesion molecule, VCAM-1. Hence, there appear to be antigen-dependent and antigen-independent forms of graft inflammation. Treatment of cardiac allograft recipients with 200-mu-g/day M/K-2 antibody retarded graft loss by only a few days, and did not interfere significantly with leukocytic infiltration, as detected by limiting dilution analysis of graft-reactive CTL, despite the fact that large amounts of M/K-2 could be detected on graft microvascular endothelia and in the peripheral blood as rejection progressed. These data indicate that VCAM is apparently not essential for the leukocytic infiltration and subsequent rejection of cardiac allografts, and is not involved in leukocytic infiltration of murine cardiac isografts.