A new microparticle size calibration standard for use in measuring smaller microparticles using a new flow cytometer

Summary. Background: Microparticle size measurements are often calibrated on flow cytometers using polystyrene microspheres that forward scatter more light vs. particle diameter than cellular microparticles. Methods: We compared theoretical with measured forward angle light scattering on the LSRII, FC500 and Apogee A40 using polystyrene and silica microspheres vs. synthetic lipid vesicles and platelets, then compared plasma microparticle counts using different calibration strategies. Results: Polystyrene and silica microspheres with higher refractive indices forward scattered more light with a wavelength of 488 nm for a given size microparticle than did lipid vesicles or platelets. The LSRII and FC500 did not count many, and were unable to separate by size, polystyrene microspheres