Table III.

Cell Types Involved in Atherosclerotic Lesions

Cell Types Involved	Activities	Events	AHA Classification
Endothelium	Oxidize LDL	Endothelial injury	None
Platelets	Produce PDGF, which has strong chemoattractant and mitogenic effect on SMC	Endothelial injury	None
T‐lymphocytes	Infiltrate into subendothelium	Endothelial injury	None
Monocytes Macrophages Foam cells	Adhesion Migrate into media Ingest oxidized LDL Formation of foam cells Stimulate migration and proliferation of SMC & connective tissue	Formation of fatty streak containing mostly lipid‐filled macrophages May progress or regress	Fatty streak (I‐III)
SMCs Monocytes Macrophages	Migrate into media Stimulate proliferation of SMC & connective tissue	Thickening of intima	Diffuse intimal thickening (IV)
SMCs Platelets	Migrate from media to intima Role in plaque growth	Fibrous plaque formation Complicated lesions with hemorrhage, thrombosis or calcification	Fibrous plaque (V and VI)
SMCs Platelets T‐lymphocytes	Accumulation in advanced atherosclerosis Role in acute coronary syndromes Cytokines from activated T‐lymphocyte cells may be involved in plaque rupture within lesions	Plaque rupture Can provoke unstable angina, MI Thrombus may become organized into lesion
AHA=American Heart Association; LDL=low‐density lipoprotein cholesterol; PDGF=platelet‐derived growth factor; SMC=smooth muscle cell; MI=myocardial infarction