B. Chazotte and M. Pettengill, Univ. of N. Carolina School of Medicine, Chapel Hill. N.C. 27599

     Laser scanning confocal microscopy was used to image membrane potentials in individual living human cells to quantitatively assess cellular and mitochondrial energy metabolism. Graylevel cell images were histogrammed using in-house software, and a lookup table divas selected to convert pixels to millivolt (mV) membrane potentials. These potentials are binned as extracellular, cellular, cytoplasmic and mitochondrial. The relative mV probability densities for areas, "integrated optical densities", and average density for each bin are then determined to assess energy transduction. This also permits the quantitative comparison among individual cells and cell populations. Our preliminary data compared human mononuclear leukocytes from a small population of CFIDS patients to healthy controls and suggests possible mitochondrial dysfunction as reported by lower cellular and mitochondrial membrane potentials and smaller areas of cells at mitochondrial potentials. More detailed studies on CFIDS patients' cells are warranted and are in progress. In related studies, interferon-alfa added to cultured human fibroblasts was found to decrease the mitochondrial membrane potentials and areas at mitochondrial potentials. Interleukin-2 decreases mitochondrial potentials and may induce an unexplained photosensitivity as reported by the membrane potentials. Supported in part by grants te B.C. from CFIDS Assoc. of America, UNC Ctr. for Res. on Chronic Illness NIH 5P30 NR03962-02, and UNC Univ. Res. Council.