Despite what is written in various places, flow cytometry can only be used for size measurement on homogenous particles such as plastic beads. It does not work for particles with complex optics such as cells. With beads, increasing size leads to increased light scatter. With cells the situation is quite different, a treatment that resulted in a 30% change in cell volume caused a light scatter decrease in a lymphoid cell line and no change in light scatter from NIH3T3 cells. Coulter volume measurements are regarded as the gold standard of cell volume measurements. I have done cell volume measurements on nucleated cells in the past with no problems. If you are not seeing changes in cell volume, than either the treatment is not causing a change or the instrument needs repair. -Jim Weaver ************************************************* * * * James L. Weaver Ph.D. * * Division of Applied Pharmacology Research * * Office of Testing & Research * * CDER MOD-1, FDA * * 8301 Muirkirk Rd, Laurel MD 20708 * * * * Phone: 301-594-5879 * * Fax: 301-594-3037 * * Email:WEAVER@CDER.FDA.GOV * * * *************************************************
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