Herein is provided a simple, reliable and accurate method for cellular analysis on hematology analyzers. In various aspects, the methods provide separation and/or differentiation between red blood cells (RBCs) and white blood cells (WBCs) by utilizing a fluorescent dye to selectively stain WBCs such that they emit stronger fluorescence signals. The method provides optimal detection limits on WBCs and RBCs, thereby allowing analysis of samples with sparse cellular concentrations. As few as one reagent may be used to prepare a single dilution for body fluid analysis, in order to simplify the body fluid analysis. Minimal damage to WBCs is attained using the lysis-free approach described in aspects of the disclosure.