AGE-immunoreactivity (AGE-IR) is increased in the coronary arteries of nondiabetic smokers. Processing of arterial sections for anti-AGE immunohistochemical analysis is described in Materials and Methods. Anti-AGE- and AEC-developed sections were examined by light microscopy. Representative results of AGE-IR in a nondiabetic nonsmoking patient (A) and a nondiabetic smoking patient (B) are shown. The lumen (L) of the vessel is indicated. Neither patient had a history of diabetes. There is extensive immunoreactivity (shown as a red reaction product) within the vessel wall of the coronary artery from the smoker. AGE-IR of the coronary artery from the nonsmoking patient is greatly reduced compared with the smoker. Magnification, ×400. (C) Composite AGE-IR in sections of coronary arteries stained with anti-AGE antibodies. Sections were from nondiabetic nonsmoking patients (n = 5), and nondiabetic smoking patients (n = 5). AGE-IR was graded per section in a blind fashion by an independent investigator. AGE-IR was significantly elevated in the sections from smokers compared with nonsmokers (p = 0.015).