Increased mitochondrial uptake of rhodamine 123 during interferon-gamma stimulation in Molt 16 cells.

The positively charged rhodamine analog rhodamine 123 accumulates specifically in the mitochondria of living cells. Mitochondria-specific interaction of this molecules is apparently dependent on the high transmembrane potential maintained by functional mitochondria (1, 2, 3). The application of such potential-dependent probes in conjunction with flow cytometry allows the monitoring of mitochondrial membrane potential in living cells (4, 5, 6). In the present work, the uptake of rhodamine 123 by Molt 16 cells stimulated by IFN-gamma or IFN-beta was measured by flow cytometry. Marked elevations in mitochondria-associated probe fluorescence have been observed in cells as early as 30-60 min after exposure of IFN-gamma but not observed by IFN-beta exposure. This results suggest that the IFN-gamma and -beta induced biological functions are different in the control of energy metabolism and energy requirements at the cellular level.