Fig 4. Detection of atherosclerotic plaques by radiolabeled CD68-Fc.

(A) (Oxidized) lipoproteins, initiate and sustain the inflammation process in atherosclerotic lesions and are essential for foam cell generation. Scavenger receptors mediate the uptake of lipoproteins into macrophages and, thus, contribute substantially to foam cell formation. (B) A soluble dimeric form of the scavenger receptor CD68 conjugated to an Fc-fragment was radiolabeled with ¹²⁴I and used to detect atherosclerosis in vivo. (C) ApoE −/− or wildtype were fed with a high cholesterol diet for 17 weeks. Subsequently, mice were injected i.v. with ¹²⁴ICD68-Fc and sacrificed after 48 hours (D) Ex vivo nuclear imaging was performed to evaluate tracer activity in the aortic arch. Activity of ¹²⁴ICD68-FC was enhanced in ApoE −/− compared to wildtype mice (lower panel) and correlated well with plaque extension as shown by sudan red staining in the aortic arch specimen (upper panel).