Photodynamic effects of protoporphyrin on the cellular level-an in vitro approach.

The purpose of this study was characterizing the phototoxic action of protoporphyrin and cellular protection mechanisms, as studied on the cellular level. In this process, active oxygen is involved. As a biological system, rat hepatocyte short-term and primary cultures were used.

A flow cytometric study of the membrane potential of natural killer and K562 cells during the cytotoxic process.

This study demonstrates that it is possible to investigate the membrane potential of interacting cells during the cytotoxic process using flow cytometry. Changes in the membrane potential of NK and K562 cells, involved in a cell-mediated cytotoxic process, were studied by standard and slit-scan flow cytometry, using the membrane potential sensitive fluorescent probe DiBAC4(3). The NK cells were labeled with a membrane marker (TR-18 or DiI) prior to incubation with K562 cells and the conjugates that were formed could be identified on the basis of the membrane marker fluorescence and light scattering signals.

A simple optical fiber device for quantitative fluorescence microscopy of single living cells.

A simple and relatively inexpensive system is described for obtaining quantitative fluorescence measurements on single living cells loaded with a fluorescent probe to study cell physiological processes. The light emitted from the fluorescent cells is captured by and transported through an optical fiber. After passage through appropriate filters the light is measured using a photomultiplier tube.

Flow cytometric measurement of [Ca2+]i and pHi in conjugated natural killer cells and K562 target cells during the cytotoxic process.

We describe a flow cytometric assay that enables one to follow conjugate formation between cytotoxic cells and their target cells during the cytotoxic process. In addition, the internal calcium concentration ([Ca2+]i) and internal pH (pHi) of the conjugated cells can be monitored and directly compared to the nonconjugated cells. This is achieved by labeling one cell type with the Ca(2+)-specific dye Fluo-3, while the other cell type is labeled with the pH-sensitive dye SNARF-1.