There is provided a combination treatment for slowing or arresting the progression and/or effecting the regression of atherosclerotic plaque deposits in a mammalian patient, said combination treatment including the administration to the patient of a cholesterol lowering drug such as a statin, and the administration to the patient of an aliquot of a patient's own blood which has been treated ex vivo with one or more stressors selected from an oxidative environment, thermal stress and UV light.