In brief, single cells are encapsulated in agarose microdrops. The microdrops are then analyzed by flow cytometry and FITC fluorescence is measured. We have successfully used this technique to quantitate IFN- g secretion from transgenic CHO cells that secrete said protein. In addition, we have been able to sort encapsulated CHO cells based on fluorescence and then return them to culture. The CHO cells grew out of the microdrops in a few days and continued to reproduce.
Studies are now underway using stimulated porcine lymphocytes from peripheral blood.
Stay tuned for updates. Collisions with chloride quench the fluorescence of SPQ making it possible to relate the measured fluorescence intensity to chloride concentration with a Stern-Volmer equation. Fluorescence excitation was provided by a UV laser and the fluorescence emission intensity at 485 nm was recorded. The utility of fluorscence lifetime flow cytometry has been demonstrated by two groups using a phase sensitive method. We well implement a novel cross correlation measurement technique, recently developed by the LFD , which should yield improved resolution of fluorescence lifetimes.