The Array Core hopes to accumulate microarray expression data that explores the view that inflammatory mechanisms are fundamental to plaque progression and plaque rupture. While this view is widely held and probably valid in the early stages of disease {Blake CR 2001;5962;4893 }, direct evidence for involvement in plaque progression in man, as opposed to fatty streak initiation in mice, remains elusive. The goal of Core A is to use the tissue and blood samples collected in the Projects to derive morphological and expression data relevant to the exploration of this hypothesis. A large part of this effort will be focused on determining if lymphocytes and monocytes can be used as sensor cells, that is, as cell types likely to report the presence of pathological states. The core will add to the effort of the Projects by exploring the possibility that analysis of mRNA content in peripheral blood monocytes and leukocytes could provide a "biomarker" for relevant states of inflammation that correlate with plaque progression. The mode for analysis of these cells is to use expression arrays to test specific hypotheses, i.e. does array based analysis have the ability to identify and cluster patients with distinct behavior of their plaques as shown by MRI, by genetic background, by a specific clinical parameter or by the presence or absence of a specific cell subset or subset specific activity or behavior. Use of expression arrays to categorize any disease, except perhaps for cancer, is still a frontier. The Core will work at this frontier and we hope our progress will give new insights into the mechanisms leading to lesion progression.