Increased atherosclerosis and glomerulonephritis in cynomolgus monkeys (Macaca fascicularis) given injections of BSA over an extended period of time.

A study was conducted to compare the effects of experimental immune complex disease on the development of glomerulonephritis and aortic and coronary artery atherosclerosis. Fourteen adult male macaques (Macaca fascicularis) were fed a mildly atherogenic diet. Ten of these animals were given repeated intravenous injections of bovine serum albumin (BSA), and the remaining 4 were given similar injections of saline. Three of the monkeys given BSA responded with a high antibody titer, 4 with a moderate titer, and 3 with a low level titer to BSA. In all 4 monkeys with the moderate antibody response glomerulonephritis developed, characterized by increased glomerular cellularity, electron-dense deposits in the glomerular capillary basal lamina, and deposits of IgG, IgM, C3, C4, and BSA. Glomerulonephritis was not seen in the other 6 monkeys given BSA or the 4 control monkeys. Aortic lesions seen at necropsy consisted of a few fatty intimal streaks with no differences between test monkeys (given BSA) and control monkeys (given saline). There was no correlation between total serum cholesterol concentration, high-density lipoprotein cholesterol concentration, or BSA antibody levels and the degree of aortic atherosclerosis. Immunochemical stains for immunoglobulins and complement components revealed increased intimal staining when intimal thickness increased. Medial staining for immunoglobulin and complement components appeared to be slightly increased in monkeys with moderately high-level titers of BSA. The extent of atherosclerosis in the coronary arteries of monkeys given BSA was greater than in the control animals. Differences in the extent and severity of the atherosclerotic lesions were most pronounced in the proximal portions of the main coronary arteries, suggesting an increased susceptibility of this site to immune-complex-exacerbated atherosclerosis. In addition to the increased lesion severity in monkeys given BSA, there were numerous granulocytes seen within, attached to, and penetrating into the intima of the coronary lesions. No correlation was seen between the development of glomerulonephritis and either aortic or coronary artery atherosclerosis.