Figure 5. Ly-6C^hi monocytes adhere preferentially to TNF-α–activated endothelium, accumulate in lesions, and differentiate to macrophages in vivo.

(A) Purified Ly-6C^hi monocyte phenotype after 24 hours in culture. (B) Adherence of blood monocytes on TNF-α–treated MHECs under laminar flow conditions. Monocyte subsets were isolated from the blood of apoE^+/+ and apoE^–/– mice on chow and Western diet. (C) Relative proportion of blood monocytes expected to adhere to activated endothelium, based on the capacity of each subset to adhere and their average abundance in peripheral blood of apoE^–/– mice on Western diet for 25 weeks. (D) Ly-6C, F4/80, and I-A^b expression of CD45.2⁺ Ly-6C^hi monocytes retrieved from aortas and spleens 24 hours after transfer into CD45.1⁺ mice (both donor and recipient apoE^–/– mice consuming a Western diet). Monocytes cultured in vitro were also analyzed. (E) F4/80 and Ly-6C coexpression on CD45.2⁺ donor cells retrieved from aortas. (F) In vivo aortic accumulation of [¹¹¹In]oxine-labeled Ly-6C^hi and Ly-6C^lo monocytes 24 hours after adoptive transfer in apoE^–/– mice on Western diet. (G) Phosphorimager plates depicting relative distribution of signal in aortas of apoE^–/– mice that received equal numbers of Ly-6C^hi apoE^–/– or Ly-6C^lo apoE^–/– monocytes. (H) Relative proportion of Ly-6C^hi and Ly-6C^lo monocytes expected to accumulate in atherosclerotic aortas, based on the capacity of each subset for aortic accumulation and their average abundance in peripheral blood of apoE^–/– mice on Western diet for 25 weeks. Shown are 1 of 2–3 independent experiments. Student’s t test was used.