Methods and compositions for inducing apoptosis of cells, such as macrophages, at a lesioned site of a body vessel are disclosed herein. Nitric oxide can be directly or indirectly delivered to a treatment site to increase macrophage apoptosis. Delivery can include site specific delivery of nitric oxide gas, nitric oxide in aqueous solution or a substance(s) which releases nitric oxide or causes nitric oxide to be generated from an endogenous source. Delivery can be achieved by a delivery system such as a catheter assembly, stent or other suitable device.