Aortic Fatty Streaks in Early Atherosclerosis

A 24-year-old male motorcyclist dies in a high-speed road traffic accident. At medicolegal autopsy, the thoracic and abdominal aorta are opened longitudinally and the intimal surface is inspected. Multiple flat, pale yellow, elongated longitudinal streaks 1–2 mm wide and up to 10 mm long are noted running parallel to the direction of blood flow, most prominent along the posterior wall of the thoracic aorta and around the ostia of the celiac and mesenteric arteries. The streaks do not protrude above the intimal level and do not disturb blood flow. Histology of the structure marked **C** shows sub-endothelial lipid-laden macrophages with frothy, vacuolated cytoplasm. Which of the following best describes the cellular composition and pathophysiologic significance of the lesion marked **C**?