Experimental induction of atheroarteriosclerosis by the synergy of allergic injury to arteries and lipid-rich diet. II. Effect of repeatedly injected foreign protein in rabbits fed a lipid-rich, cholesterol-poor diet.

Rabbits fed a lipid-rich, cholesterol-poor diet and given concomitant injections of foreign protein, over a period as long as 17 months, developed in their coronary arteries both a) proliferative fibromuscular intimal thickening closely resembling the diffuse intimal thickening that commonly occurs in coronary arteries of man, and b) fatty-proliferative fibromuscular intimal thickening that closely resembles coronary atherosclerosis in man. In contrast, rabbits of another group that were concurrently fed the same diet for as long as 22 months without injections of foreign protein developed changes in arteries of their hearts that resemble neither coronary atherosclerosis nor diffuse intimal thickening in man. Fatty-proliferative changes in aortas of the first group of rabbits are strikingly greater and more closely resemble human aortic atherosclerosis than those in the latter group. In the course of the experiments, the average serum cholesterol was not significantly different in the two groups of rabbits. It was approximately 200 to 250 mg%, which is the average serum cholesterol in adult humans in the United States. These experiments support the hypothesis that the synergy of arterial injury, in particular immunologic injury, and a diet rich in lipid can lead to atherosclerosis in man.