Induction of DNA strand scissions in HeLa cells by human polymorphonuclear leucocytes activated by Chlamydia trachomatis elementary bodies

Incubation of human polymorphonuclear leucocytes (HPMN) with Chlamydia trachomatis elementary bodies (EB) or phorbol 12-myristate 13-acetate (PMA) resulted in the production of superoxide anions (.O2-) and hydrogen peroxide (H2O2). Exposure of HeLa cells to EB- or PMA-activated HPMN and to EB alone, for 2 h, resulted in the formation of DNA strand scissions (nicks) in the HeLa cells. The nicks were visualized by incorporation of biotin 11-dUTP with its detection by streptavidin-peroxidase, and quantified by using [3H]dCTP in the in situ nuclear nick-translation reaction. Catalase, and to a lesser extent superoxide dismutase, reduced the amount of nicks induced by the EB- or PMA-activated HPMN. The possible relationship between the activity of PMN in chlamydial infections and the development of chronic diseases is discussed.