Development of intimal lesions after leukocyte migration into the vascular wall.

A model was developed to study the role of leukocytes in the development of vascular lesions. Implantation of an endotoxin-soaked cotton thread in the adventitia on the ventral side of the rat femoral artery resulted in leukocyte migration into the vessel wall exclusively in the ventral half of the vessel. Leukocyte migration occurred from both the luminal and adventitial side and consisted of neutrophils and mononuclear cells. Smooth muscle cell rich intimal lesions localized to the ventral half of the vessel were first observed 1 week after implantation. Lesions remained localized to the ventral half of the vessel wall through the 6th week. When leukocyte migration into the vessel wall was inhibited by treatment with dexamethasone, lesion development did not occur. These results suggest that leukocytes can stimulate smooth muscle cell migration into the intima and result in intimal lesion formation.