Effects of Hoechst 33342 on survival and growth of two tumor cell lines and on hematopoietically normal bone marrow cells.

Our objective in this investigation was to determine whether Hoechst 33342, which is widely recognized as a DNA specific fluorochrome for living cells, is in fact nontoxic and kinetically nonperturbing at dye concentrations required to achieve acceptable DNA distributions. Three cell types were tested: HeLa S-3; SK-DHL2, a human lymphoma cell line; and hematopoietically normal human bone marrow cells. In the third system, only the cloning efficiencies were determined. Results differed considerably for the different cell types. While HeLa cells yielded excellent DNA distributions and were almost completely resistant to the cytotoxic and cytokinetic effects of the dye, SK-DHL2 cells were highly sensitive to the fluorochrome even at dye concentrations which produced very poor DNA distributions. Human bone marrow cells were intermediate in their stainability and toxicity response, and acceptable DNA distributions could be obtained at the nontoxic dye concentration of 2.5 muM. Clearly, different cell types differ considerably with respect to their cytotoxic and kinetic responses to Hoechst 33342. In some cases it may not be possible to ensure adequate staining of the cells for flow cytometry without significantly altering their viability and/or proliferative behavior.