CD33 and acute myeloid leukemia: For tube 3 of the EF AML/MDS panel, PC1 indicated that the most useful parameters for group separation were FSC (13%) and SSC (11%), whereas PC2 showed that the best discriminating factors for tube 3 of the EF AML/MDS panel were HLA-DR (32%), CD34 (21%), and CD33 (13%), allowing for good separation between t(15;17) AML blasts, normal erythroid-committed HPCs, and blasts from other AML categories.