The phagocytic activity was determined in human polymorphonuclear leucocytes using the flow cytometry technique with microspheric hydrophilic particles labelled with fluorescein isothiocya- nate. Non-specific adherence of particles is discussed and normal values of phagocytic activity are presented. The advantages of this method include simplified sample preparation using whole blood, rapidity of the test, precise phagocytosis quantification and possibility of archiving all findings in a computer.

        Key words: polymorphonuclear leucocytes – phagocytosis – ingestion – flow cytometry.