[Immunocytochemical investigations of occluded saphenous vein grafts].

Occluded saphenous vein aorto-coronary bypass grafts were investigated using two types of monoclonal antibodies, specific to either the muscle actin (HHF 35) or the macrophage (HAM 56). The early post operative occlusions of saphenous vein grafts were associated with the deposition of mural thrombi with little intimal proliferation. The late occlusions of saphenous vein grafts were associated with intimal fibrous proliferation without mural thrombus formation. Proliferated smooth muscle cells were a major constituent of intimal fibrous proliferation in both early and late occluded grafts. Macrophages were not detected in both groups. The proliferation of smooth muscle cells in the intima may play a role in the development of late occlusion, rather than the organizational process of accumulated mural thrombi.