Is the central dogma of flow cytometry true: That fluorescence intensity is proportional to cellular dye content?

Measurements and theoretical calculations of fluorescent emission from four samples of polystyrene microspheres (diameter 0.92, 1.63, 1.90 and 4.18 m̈m) containing the same fluorescent dye show a general dependence upon particle size, emission angle, and polarization conditions. However, for the excitation and detection conditions used in flow cytometry, the relative fluorescent intensities measured for the four particle sizes are proportional to the dye content to +10% accuracy, independent of particle size. Accordingly, the central dogma of flow cytometry ‘that fluorescence is proportional to cellular dye content’ is valid to this accuracy for these solid, highly refractive polymer particles. Most mammalian cells are much less refractive, therefore, should conform more closely to the central dogma.