Role of Gas6 in graft destruction of mouse heart grafts exposed to warm ischemia. (A-F) Hematoxylin and eosin (A,D) and CD45 (E,F) stainings of sections through WT and Gas6^−/− mouse heart grafts, 10 days after transplantation, revealed profound inflammatory cell infiltration and myocardial cell necrosis (A,C,E) in the WT heart graft. In contrast, the Gas6^−/− transplanted heart graft showed a remarkably normal morphology and only limited leukocyte infiltration (B,D,F). (G-I) Immunostaining for VWF (brown) combined with nuclear counterstaining with Harris hematoxylin (blue) revealed platelets (arrowhead in panel H), leukocytes, and platelet-leukocyte conjugates (arrowhead in panel G) adhering to the wall of the coronary vessels in the graft of WT mice, whereas this was not seen in hearts transplanted in Gas6^−/− mice (I). VCAM-1 (J,K) and ICAM-1 (L,M) up-regulated expression is reduced in Gas6^−/− hearts transplanted into Gas6^−/− mice (K,M) compared with WT cardiac grafts, dissected 3 days after transplantation into WT mice (J,L). Bar represents 100 μm in panels A and B, 50 μm in panels C-F and J-M, and 10 μm in panels G-I.