BACKGROUND: Shortening of mean telomere length (TL) in white blood cells is correlated with the development of coronary heart disease (CHD) and with increased mortality due to infectious disease. The goal of the present study was to investigate whether telomere shortening in CHD is restricted to specific peripheral blood lymphocyte and/or myeloid cell subpopulations. Results were correlated to TL in CD34+ hematopoietic peripheral blood stem cells and progenitor cells obtained from the same individual patients. METHODS AND RESULTS: TL was measured by multicolor flow cytometry-fluorescent in situ hybridization in 12 leukocyte subpopulations after immunomagnetic bead sorting. We investigated TL in 14 young (mean age 25 years) and 13 older (mean age 65 years) healthy male volunteers and in 25 age-matched patients with CHD (mean age 65 years). We show that TL in granulocytes and monocytes mirrors TL of CD34+ peripheral blood stem cells and progenitor cells extremely well (r=0.95, P
