Fluorescence activated cell fluorochromes

The hematopoietic lineage originally was worked out by Injecting the various types of precursor cells into mice whose precursor cells had been wiped out by irradiation. By observing which blood cells were restored in these transplant experiments, researchers could infer which precursors or terminally differentiated cells (e.g., erythrocytes, monocytes) arise from a particular type of precursor. The first step in these experiments was separation of the different types of hematopoietic precursors. This is possible because each type produces unique combinations of cell-surface proteins that can serve as type-specific markers. If bone marrow extracts are treated with fluorochrome-labeled antibodies for these markers, cells with different surface markers can be separated in a fluorescence-activated cell sorter (see Figure 5-34). 

Fig. 6. Activation of caspases detected by the fluorochrome-labeled caspase (FLICA) inhibitors assay. FiL-60 cells were untreated (A), treated in culture with camptothecin to induce apoptosis (B) (ref. 26). The cells were then electrostatically attached to microscope slides, incubated with staining solution of FAM-VAD-FMK as described in the protocol, and their green fluorescence (integrated value and pixel of maximal intensity) measured by LSC. Note the appearance of apoptotic cell subpopulation characterized by the increased green fluorescence (above the marked threshold level of the maximal pixel) reflecting activation of caspases that bind FAM-VAD-FMK.

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