EVALUATION OF INDIUM-111-POLYCLONAL IMMUNOGLOBULIN-G TO QUANTITATE ATHEROSCLEROSIS IN WATANABE HERITABLE HYPERLIPIDEMIC RABBITS WITH SCINTIGRAPHY - EFFECT OF AGE AND TREATMENT WITH ANTIOXIDANTS OR ETHINYLESTRADIOL

Scintigraphic detection of atherosclerotic lesions using In-111-polycl onal IgG was studied. In Watanabe heritable hyperlipidemic (WHHL) rabb its, an animal model for hypercholesterolemia with spontaneous atheros clerosis, aged WHHL rabbits incorporated more In-111-IgG into atherosc lerotic lesions than young WHHL or control NZW rabbits. This result is in agreement with histological analysis. However, due to the low rati o of lesion-incorporated radioactivity to circulating radioactivity, i n vivo gamma imaging of atherosclerosis with In-111-IgG scintigraphy w as unsuccessful. Interventional agents, Probucol or vitamin E, used fo r 28 days to reduce the amount of autoantibodies produced against biol ogical modified low-density lipoproteins did not produce differences i n In-111-IgG incorporation into the aorta ex vivo. Ethinylestradiol, u sed for 28 days, exhibited similar incorporation with decreased serum cholesterol by 45%. Although atherosclerosis histology and lesion surf aces of WHHL rabbits are similar to those in adult humans, it is obvio us that noninvasive gamma imaging with polyclonal In-111 scintigraphy is not reliable for serial evaluation of the extent of atherosclerosis . Our results emphasize the need to develop pharmaceuticals to image a therosclerosis.