PubMed · 1251180
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L A Herzenberg, R G Sweet. 1976. Fluorescence-activated cell sorting.. https://doi.org/10.1038/scientificamerican0376-108
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Gravitational field-flow fractionation is used for the separation of particles according to their sizes in the range 1-100 microns: larger particles elute before smaller ones. This phenomenon can be explained as a result of the steric exclusion of the particles from the vicinity of the channel walls, and/or hydrodynamic effects supposedly associated with the inertia of the liquid. The method was used for the investigation of red blood cells. The dependence of the retention ratio on the flow-rate, sample volume, concentration of blood and relaxation time was studied. Analysis of fifteen individual fractions by Coulter counter and reinjection of three other fractions were studied in order to verify fractionation of red blood cells.
The characterization and quantification of biomass is often time consuming and dependent on the cultivation media and gives no detailed information between cell size and shape and their productivity. By monitoring the bioprocess with steric sedimentation field-flow fractionation (Sd/StFFF) in combination with laser light scattering, not only cell growth, but also the variation of cell size and shape during the cultivation, can be observed. In this work, the feasibility of separating and characterizing cell populations by steric sedimentation field-flow fractionation is demonstrated by its application to three different yeast cultivation broths. For this purpose samples which were collected at different cultivation times were injected into an FFF system. Fractograms were obtained in less than 4 min. Due to the relatively high resolution of the method, a cell sample could be fractionated in several subpopulations differing in their size as well as in their number of buds.
BACKGROUND: Natural killer (NK) cells may provide a first line of defense against the metastatic implantation of circulating tumor emboli. Because tumor emboli are discharged systemically in patients undergoing solid tumor resection, it is important to determine the nature of surgical-stress impairment of perioperative NK cell cytotoxic function. METHODS: The authors studied 85 patients undergoing surgical resection of solid tumors, most of whom had an abrupt and marked decrease in NK cell cytotoxicity that was detectable within 18 hours of surgical resection. RESULTS: This impairment was not caused by rapidly emerging suppressor cells (measured in autologous effector cell mixing studies) or decreased NK cell frequency in the peripheral blood (assessed phenotypically and morphologically). Instead, surgical stress exerted a direct "toxic" effect on NK cells that could be localized to a specific phase of the NK cell tumor lysis cycle. Tumor binding and the first round of tumor lysis were intact postoperatively (measured in single-cell assays). However, postbinding programming for lysis was decreased sharply after surgery (assessed by calcium pulse assays). In addition, the kinetics of lysis and the rate of lytic programming were slower after surgery (assayed in target saturation kinetic chromium-51 release tests). CONCLUSIONS: These latter defects probably were related to the programming for lysis deficiency because postprogramming NK cell maximal recycling capacity was not affected by surgical stress.