Figure 4.

Analysis of HL expression in aortic lesions after BMT. Macrophages were identified in aortic lesions from apoE-KO (a) and apoE-KO × HL-KO (c) mice by immunohistochemistry using an antibody against the mouse macrophage antigen Mac-3 and counterstained with hematoxylin. HL mRNA was detected by in situ RNA hybridization using the mouse HL digoxigenin-labeled antisense riboprobe (b, d, e, and g), which was detected by fast red dye. To enhance visualization of the mRNA, no counterstaining was performed in aortic sections analyzed by in situ RNA hybridization. HL mRNA is present in aortic lesions from apoE-KO mice (b) but is undetectable in apoE-KO × HL-KO mice (d) before transplantation. After BMT (chow diet), HL mRNA was present in aortic lesions from the apoE-KO → apoE-KO × HL-KO mice (e), demonstrating population of aortic lesions in recipient mice by apoE donor macrophages. In contrast, very little HL mRNA was present in aortic lesions from apoE-KO mice after transplantation of donor HL-KO × apoE-KO mouse macrophages (apoE-KO × HL-KO → apoE-KO) (g). As expected, after BMT, only background signal was detected in aortic lesions hybridized with the control HL sense riboprobe (f and h).