Immunolabeling of a microgranular APL case (A) and of an acute nonlymphoid leukemia M4 subtype (B) with the PG-M3 MoAb. (A) Indirect immunofluorescence with rhodamine-labeled antibody and nuclear DAPI counterstain. Double arrows show a microspeckled distribution of the PML/RAR protein within the nuclei of APL cells. This pattern contrasts with the nuclear speckled positivity PML wild type of normal residual hematopoietic elements (single arrow). (B) Indirect immunofluorescence with fluoresceine-labeled antibody and nuclear DAPI counterstain. Blast cells show the nuclear speckled positivity.