Flow cytometric analysis of blood cells is an important technique for the differential diagnosis of leukemias. With regard to the analysis of leukemia cells, the combined use of intracellular antigens or nuclear DNA content with other routine cellular surface markers is quite useful for the analysis of immunophenotyping, and enables the differentiation of leukemia cells from the contaminating non-malignant cells, particularly in the analysis of the minimal residual diseases (MRD). We established a flow cytometric method for the simultaneous detection of cell surface antigens, intracellular antigens and relative DNA content. The reagent consists of phosphate-buffered saline containing 0.5% paraformaldehyde and 0.5% saponin (PFS) for fixation and permeabilization of cells. The method permits rapid cell processing, preservation of cell surface antigens, and sensitive staining of intracellular antigens. The method also exhibits very low coefficients of variation in the determination of nuclear DNA content. Use of this flow cytometric method substantially facilitates the diagnosis and detection of leukemia cells.
