Radionuclide imaging of experimental atherosclerosis with nonspecific polyclonal immunoglobulin G

The utility of nonspecific polyclonal IgG for external imaging of experimental atherosclerosis was tested in a series of rabbits after balloon catheter deendothelialization of the abdominal aorta. Following injection of 111In-IgG, 111In-Fc, or 111In-Fab serial images were recorded. In addition, several animals received 125I-low density lipoproteins [125I-LDL], or 125I human serum albumin [125I-HSA] as positive and negative controls. Forty-eight hours after injection of the radiolabeled proteins, the aortas were removed, divided into abdominal and thoracic regions, counted, and autoradiographed. The images acquired after injection of 111In-IgG and 111In-Fc, showed clear focal accumulation of radioactivity in the healing abdominal aorta. In contrast, the images obtained after injection of 111In-Fab did not show focal radionuclide accumulation. For 111In-IgG and 111In-Fc there were three to six times as many counts in the abdominal as in the thoracic aorta, while for 111In-Fab and 125I HSA, the abdominal and thoracic counts were nearly equal. The results suggest that radiolabeled IgG and Fc can be used to image experimental atherosclerosis.