DDT induces apoptosis in human mononuclear cells in vitro and is associated with increased apoptosis in exposed children

The aim of the present work was to investigate whether DDT and its metabolites are able to induce apoptosis of human peripheral blood mononuclear cells (PBMC) both in vitro and in vivo. Cells isolated from healthy individuals were incubated in the presence of increasing concentrations of p′p-DDT, p′p-DDE, or p′p-DDD (0–150 μg/mL) for different intervals. Apoptosis was then determined by flow cytometry (DNA cell content analysis) and fluorescence microscopy (Hoechst staining). A significant level of apoptosis was induced by DDT, DDD, and DDE at 80 μg/mL compared to controls, reaching a maximum effect at 100 μg/mL. We began to detect apoptosis at 12 h, with a maximum effect at 24 h of incubation. These results were confirmed using the TUNEL assay in cells treated with the three compounds tested as well as with o′p-DDT at 100 μg/mL and 24 h of incubation. Our data demonstrate that DDT and its metabolites are able to induce apoptosis of human PBMC in vitro. Therefore, we performed a preliminary study in children exposed to this insecticide. When compared to a control population, the exposed children had higher levels of DDT, DDD, and DDE in blood and also had a higher frequency of apoptosis. In the exposed children, a weak positive association was found between the frequency of apoptosis and the exposure to DDT and DDE. Our results showed that more studies are needed in people exposed to DDT, as apoptosis may cause serious public health effects such as immunosuppression.