A cytotoxic substance in insect cell culture spent media

Summary Spent media from five different insect cell lines when inoculated intoTrichoplusia ni (TN-368) cultures produced cytotoxicity resulting in rounding and detachment of cells. The substance in spent medium from the established cell lineCarpocapsa pomonella (CP-169) is believed to be a toxin, based on the failure to serially passage the agent, the early appearance of the cytotoxic effect, and the inability to detect microbes by culturing techniques as well as by electron microscopy. The ability to extract the toxic substance from CP-169 cells indicates that it is cell associated. Biophysical and biochemical properties of the CP-169 cytotoxin are presented.