Kit for Paroxysomal Nocturnal Hemoglobinuria (PNH) whit three-color direct immunofluorescence reagent for use in flow cytometry to evaluate the possible loss of expression of the glycosylphosphatidylinositol (GPI) anchor (GPI-anchored proteins) molecule on neutrophils and on monocytes. Kit includes monoclonal antibodies combination: CD157/CD45/CD64.