Initial characterization of a peripheral blood mononuclear cell chemoattractant derived from cultured arterial smooth muscle cells

A mononuclear cell chemoattractant of high specific activity produced by baboon (Papio cynocephalus) aortic medial smooth-muscle cells (SMCs) in culture has been partially characterized. Smooth-muscle cells, between the third and eighth passage, were grown to confluence in Medium 199 containing 10% fetal calf serum and then incubated for 24 hours in either serumless medium (Neuman and Tytell) or Medium 199 containing 0.2% bovine serum albumin. The 24-hour SMC-conditioned medium was fractionated on Sephadex G100-Superfine and potent chemoattractant activity (SMC-CF) eluted in the 10,000-12,000 dalton region. SMC-CF displayed chemotactic and chemokinetic activity for peripheral blood mononuclear cells but not for polymorphonuclear leukocytes. Production of SMC-CF by the cells was significantly inhibited in the presence of cycloheximide, and its activity was abolished after incubation with the bacterial protease subtilisin. Chromatofocusing experiments indicate that SMC-CF is a cationic protein with a pI of >10.5. The role SMC-CF may play as an inflammatory mediator in monocyte recruitment to the arterial intima in atherogenesis is discussed.