Background. Detection of membrane molecules by immunophenotypisation is a routine counterpart of the laboratory tests which are needed for the complex diagnostic procedures of hematopoetic malignancies at present. The immunochemical detection of intracellular molecules is essential in such cases, where the expression of surface molecules on malignant cells is poor, or where the results of other diagnostic analyses are unequivocal (cases with ectopic expression of other lineage-specific molecules and cases of biphenotypic leukemias). Methods and Results. We followed the procedure using 4% solution of paraformaldehyd in phosphate buffered saline for fixation of cells. Lysing solution G (Becton-Dickinson) was used for permeabilisation of cells to detect nuclear and cytoplasmatic molecules. The permeabilised cell suspension was than washed with 0,5% solution of Tween 20 in phosphate buffered saline. This simple and rapid procedure is readily available for the routine detection of intracellular molecules. This approach is important for the diagnosis of hematopoetic malignancies.

        Key words: immunophenotypisation, flow cytometry, cytoplasmatic molecules, nuclear molecules.