Evaluation of catechol-induced DNA damage in human lymphocytes: A comparison between freshly isolated lymphocytes and T-lymphocytes from extended-term cultures

Extended-term cultures of proliferating human T-lymphocytes (ETC) may be a practical alternative to freshly isolated non-proliferating peripheral blood lymphocytes (PBL) when studying genotoxicity in vitro. To investigate if the pattern of DNA damage differs between the two in vitro systems, catechol-induced DNA damage was evaluated in PBL and ETC derived from the same blood sample, using three different donors. DNA damage was monitored using the comet assay. Whereas 3 h of exposure to 0.5 mM catechol was found to be without DNA damaging effects, 3 mM was found to induce significant damage both in the PBL and the ETC (the latter being clearly less sensitive). The level of reactive oxygen species (ROS) was also measured in the ETC using the fluorescent probe carboxy-H2DCFA. ROS was found to be considerably increased both at 0.5 and 3 mM catechol. The demonstrated difference in sensitivity towards catechol-induced DNA damage between PBL and ETC may be due to their different proliferative status, but despite this difference both in vitro systems were able to identify catechol as a DNA damaging agent at the same concentration.