Deposition of C4d and C3d in cardiac transplants: A factor in the development of coronary artery vasculopathy

(A) Immunohistochemistry (IHC) staining of C3d on post-transplant myocardial biopsies. A biopsy with Grade 1 deposition. Weak staining, on a few of the larger vessels, not found ubiquitously throughout the tissue (original magnification ×100). (B) Grade 1 deposition at a higher magnification. Very few of the intramyocyte vessels have C3d deposition (original magnification ×400). (C) Grade 3 C3d deposition. Throughout the tissue there is strong staining on intramyocyte vessels. There is some serum staining in the tissue, but only deposition on the endothelium was scored on the grading system. Larger capillaries also have C3d deposits (original magnification ×100). (D) Grade 3 deposition at a higher magnification. All intramyocyte vessels have C3d deposition on the endothelium (original magnification ×400).

IHC staining for the macrophage marker CD68 (original magnification ×400). This marker was used to demonstrate intravascular macrophages in biopsies that had been selected from routine hematoxylin–eosin staining as positive for AMR.