Reagent and process for the identification and counting of biological cells

A process for the identification and counting of biological cells in a sample comprising erythrocytes, the process comprising the following operations in a single stage:

• simultaneously lysing the erythrocytes by mixing and incubating the sample with a cell lysing agent comprising at least one detergent in a concentration capable of specifically lysing erythrocytes in the sample at least one membrane fixing agent, and a membrane penetration agent selected from the group consisting of an ionophore compound of the protonophore type, an ionophore of the antibiotic type, and a mixture of ionophores, and
• staining intracellular nucleic acids of unlysed cells,
• to provide a mixture of lysed erythrocytes and unlysed cells having stained intracellular nucleic acids, and
• identifying and counting the unlysed cells by flow cytometry using at least two measuring parameters selected from the group consisting of resistive volume, axial luminous diffraction, axial luminous transmission, orthogonal light scattering, and fluorescence.