Cell-mediated cytostasis: A critical analysis of methodological problems

Abstract The experimental evidence supporting the existence of cell-mediated cytostasis (CMS) was examined according to some of the known various interactions taking place in culture systems. Possible sources of misinterpretation were (i) the culture conditions affecting label uptake e.g., the shape of the culture vessel and the specific activity of the radiolabeled nucleoside; (ii) the degree of effector cell activation, stimulated effector cells taking up more label than nonstimulated cells; (iii) the effects of supernatant giving a non-H-2 specific inhibition of label uptake but no corresponding decrease in cell number; and (iv) cytolytic effects generated during the culture. These effects, some of which can mimic CMS, were demonstrated experimentally and discussed. The reports in the literature on CMS were reviewed and compared to our experimental findings. It is concluded that experimental conditions for unambiguous demonstration of CMS may be very difficult to meet.