Is there a difference between T- and B-lymphocyte morphology?

We characterize T- and B-lymphocytes from several donors, determining cell diameter, ratio of nucleus to cell diameter, and re- fractive index of the nucleus and cytoplasm for each individual cell. We measure light-scattering profiles with a scanning flow cytometer and invert the signals using a coated sphere as an optical model of the cell and by relying on a global optimization technique. The main difference in morphology of T- and B-lymphocytes is found to be the larger mean diameters of the latter. However, the difference is smaller than the natural biological variability of a single cell. We propose nuclear inhomogeneity as a possible reason for the deviation of mea- sured light-scattering profiles from real lymphocytes from those ob- tained from the coated sphere model. © 2009 Society of Photo-Optical Instru-