Quantitative analysis of inflammatory cells in aortic atherosclerosis of young adults

Cellular analysis of aortic atherosclerotic lesions has been pursued extensively in recent years, although most of these investigations have involved the detection of inflammatory cells in chronically diseased tissue or artificially induced atherosclerosis in an animal model. Few studies have attempted to quantify accurately, using computer analysis systems, the degree of cellular infiltration in a statistically significant number of samples, in tissue from young adults. In this study, segments of human aortae were collected at autopsy from 29 individuals ranging in age from 15 to 35 years. The tissue was embedded in paraffin and stained using routine histological and automated immunohistochemical staining techniques. The sections were evaluated using advanced image analysis techniques to investigate the differences in cellular composition and cell activation between the dorsal and ventral aspects of the human aorta and to correlate these findings to the age of the subjects. These regions have been previously shown to have a high (dorsal) and low (ventral) probability of developing sudanophilic lesions. Our data demonstrated that statistically different cell populations exist in the dorsal and ventral regions of each vessel. The dorsal aspect (i.e., high-probability region) had a greater number of HAM56(+) (36.9% increase,p = 0.0002) and HLA-DRα(+) cells (44.2% increase,p = 0.0035) than did the ventral surface (i.e., low-probability region), although there were no significant differences in the number of CD43(+) lymphocytes. When grouped according to age, results showed significant increases in the dorsal region when considering HAM56(+) and HLA-DRα(+) cells (p = 0033 and 0.046, respectively). Morphologically, a greater number of foam cell aggregates were found to occur in the dorsal region of the vessel than in the ventral portion. Our results indicate that the microarchitecture and cellular composition of the dorsal and ventral aorta are significantly different, with these variations becoming more marked with age.