Flow cytometric probes of early events in cell activation

By now, it's well established that the surface of a cell Contains transmembrane proteins which, on binding ligands, tell The biochemical computer inside what to do Without a need for any of the ligands coming through. Receptor‐triggered cytoplasmic “interrupt routines” May lead the nucleus to activate new sets of genes, Or otherwise induce a cell, which never reasons why, To twitch, secrete, endocytose, or reproduce, or die. By merely watching labeled ligands bind, we cannot know Down which of many paths the cells thus tagged are apt to go, But other changes, shortly after binding, may predict Which of its several options any given cell has picked. Flow cytometric methods are described here which allow Membrane potential to be estimated, to show how Potential changes may occur in seconds after binding Of ligand to a functional receptor, or for finding No change when cells don't have the right receptor, or can't see The ligand for antagonists of like affinity. With chlorotetracycline fluorescence, one can find Release of membrane calcium soon after ligands bind; Both this and the potential measurement can help support Decisions in an instrument about which cells to sort, Though narrowing the distributions which these methods yield Would greatly help to broaden applications in this field.