FIGURE 4

Transglutaminase is found in endothelium and smooth muscle cells (SMC) and co-localizes with isopeptide. The proximal left anterior descending coronary artery was excised from the explanted heart of a 45-year-old male undergoing transplantation for ischemic cardiomyopathy. The artery was fixed in neutral buffered formalin, paraffin-embedded, and processed for IHC. A, Distribution of TG antigen, which is similar to that of the isopeptide (B). C, Distribution of SMC (detected with anti-SMC actin) and D, distribution of the luminal endothelium (detected with anti-von Willebrand factor). TG antigen was strongly immunoreactive along the luminal endothelial border (shown by the black arrows), throughout the intima, and in the medium of the vessel. The detection of TG antigen in the intima and medium of the vessel is similar to the distribution of SMC. The internal elastic lamina is indicated in all figures by the white arrowheads. Original magnification, 400.