Effect of oncolytic anaerobic spores on animal cell cultures.

Germinated spore suspensions of Clostridium M55 or Clostridium C185 added to 11 animal cell cultures propa gated in vitro exerted cytotoxic and inhibitory effects only on certain types of cells. Resistance of some cell cultures seemed to be related to the diploid character, while the sensitivity of others was related to the heteroploid char acter, which is a feature of most cancer cells. After only 20 to 30 hr of contact, sensitivity of heteroploid cells to germinated clostridial spores was observed. Karyokinetic activity was arrested and cells, instead of elongating, re mained spheroid; intracytoplasmic granules appeared and the nucleus became pyknotic. Finally, some of the cells became detached from the monolayer and eventually formed debris which could easily be seen after 3 to 5 days contact. Since at no time did the germinated clostridial spores penetrate inside the animal cells, it would appear that they act at a distance, presumably through the agency of a soluble substance.