RADIATION-INDUCED APOPTOSIS IN THYMOCYTES - PH SENSITIZATION

Thymocytes were used as a model system to study the effect of microenv ironmental pH changes on the radiation-induced apoptosis. We found tha t the sensitivity of thymocytes toward radiation induced apoptosis is increased by increasing the pH of the incubation medium. The major sen sitivity change occurs between pH 7 and 8. In a given cell suspension the results obtained where similar when the apoptosis evaluation was c arried out either by counting the picnotic nuclei, or monitoring the f raction of apoptotic nuclei by flow cytometry; both methods show a rad iosensitization when the pH value of incubation media rises from 7 to 8. These results may be important when ''in vitro'' experiments are pe rformed with lymphoid cells, since changes in pH of the media may dete rmine important changes in the results.