Phagocytic activity of Agtr1^–/– and Agtr1^+/+ macrophages. (a) Fluorescent beads were injected into the peritoneal cavity after macrophage induction by thioglycollate, and the exudate was analyzed by flow cytometry for in vivo assay of phagocytosis. Histograms include Agtr1^+/+ macrophages, Agtr1^+/+ macrophages treated with 10^–6 M losartan, and Agtr1^–/– macrophages. Three separate experiments were carried out, and representative results are shown. (b) Peritoneal macrophages were incubated in vitro with fluorescent beads, and the phagocytic activity was analyzed by flow cytometry. Histograms include fluorescent beads only, Agtr1^+/+ macrophages incubated without fluorescent beads, and Agtr1^+/+ and Agtr1^–/– macrophages incubated with fluorescent beads. The mean fluorescence intensity level (lin Mean X) of each peak is shown for fluorescent beads only. The percentages of macrophages with multiple beads (more than eight) are shown next to the Agtr1^+/+ and Agtr1^–/– histograms, respectively. R1 denotes the peak derived from one fluorescent bead; R2, two beads; R3, three beads; and R4, four beads. Three separate experiments were carried out, and representative results are shown. (c) In vitro phagocytosis of fluorescent beads by Agtr1^–/– (left) and Agtr1^+/+ (right) macrophages viewed under a light microscope. Magnification, ×400. (d) In vivo phagocytosis of fluorescent beads by Agtr1^–/– (left) and Agtr1^+/+ (right) macrophages. Magnification, ×400.